Java example source code file (c1_LinearScan.cpp)
The c1_LinearScan.cpp Java example source code
/*
* Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "c1/c1_CFGPrinter.hpp"
#include "c1/c1_CodeStubs.hpp"
#include "c1/c1_Compilation.hpp"
#include "c1/c1_FrameMap.hpp"
#include "c1/c1_IR.hpp"
#include "c1/c1_LIRGenerator.hpp"
#include "c1/c1_LinearScan.hpp"
#include "c1/c1_ValueStack.hpp"
#include "utilities/bitMap.inline.hpp"
#ifdef TARGET_ARCH_x86
# include "vmreg_x86.inline.hpp"
#endif
#ifdef TARGET_ARCH_sparc
# include "vmreg_sparc.inline.hpp"
#endif
#ifdef TARGET_ARCH_zero
# include "vmreg_zero.inline.hpp"
#endif
#ifdef TARGET_ARCH_arm
# include "vmreg_arm.inline.hpp"
#endif
#ifdef TARGET_ARCH_ppc
# include "vmreg_ppc.inline.hpp"
#endif
#ifndef PRODUCT
static LinearScanStatistic _stat_before_alloc;
static LinearScanStatistic _stat_after_asign;
static LinearScanStatistic _stat_final;
static LinearScanTimers _total_timer;
// helper macro for short definition of timer
#define TIME_LINEAR_SCAN(timer_name) TraceTime _block_timer("", _total_timer.timer(LinearScanTimers::timer_name), TimeLinearScan || TimeEachLinearScan, Verbose);
// helper macro for short definition of trace-output inside code
#define TRACE_LINEAR_SCAN(level, code) \
if (TraceLinearScanLevel >= level) { \
code; \
}
#else
#define TIME_LINEAR_SCAN(timer_name)
#define TRACE_LINEAR_SCAN(level, code)
#endif
// Map BasicType to spill size in 32-bit words, matching VMReg's notion of words
#ifdef _LP64
static int type2spill_size[T_CONFLICT+1]={ -1, 0, 0, 0, 1, 1, 1, 2, 1, 1, 1, 2, 2, 2, 0, 2, 1, 2, 1, -1};
#else
static int type2spill_size[T_CONFLICT+1]={ -1, 0, 0, 0, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 0, 1, -1, 1, 1, -1};
#endif
// Implementation of LinearScan
LinearScan::LinearScan(IR* ir, LIRGenerator* gen, FrameMap* frame_map)
: _compilation(ir->compilation())
, _ir(ir)
, _gen(gen)
, _frame_map(frame_map)
, _num_virtual_regs(gen->max_virtual_register_number())
, _has_fpu_registers(false)
, _num_calls(-1)
, _max_spills(0)
, _unused_spill_slot(-1)
, _intervals(0) // initialized later with correct length
, _new_intervals_from_allocation(new IntervalList())
, _sorted_intervals(NULL)
, _needs_full_resort(false)
, _lir_ops(0) // initialized later with correct length
, _block_of_op(0) // initialized later with correct length
, _has_info(0)
, _has_call(0)
, _scope_value_cache(0) // initialized later with correct length
, _interval_in_loop(0, 0) // initialized later with correct length
, _cached_blocks(*ir->linear_scan_order())
#ifdef X86
, _fpu_stack_allocator(NULL)
#endif
{
assert(this->ir() != NULL, "check if valid");
assert(this->compilation() != NULL, "check if valid");
assert(this->gen() != NULL, "check if valid");
assert(this->frame_map() != NULL, "check if valid");
}
// ********** functions for converting LIR-Operands to register numbers
//
// Emulate a flat register file comprising physical integer registers,
// physical floating-point registers and virtual registers, in that order.
// Virtual registers already have appropriate numbers, since V0 is
// the number of physical registers.
// Returns -1 for hi word if opr is a single word operand.
//
// Note: the inverse operation (calculating an operand for register numbers)
// is done in calc_operand_for_interval()
int LinearScan::reg_num(LIR_Opr opr) {
assert(opr->is_register(), "should not call this otherwise");
if (opr->is_virtual_register()) {
assert(opr->vreg_number() >= nof_regs, "found a virtual register with a fixed-register number");
return opr->vreg_number();
} else if (opr->is_single_cpu()) {
return opr->cpu_regnr();
} else if (opr->is_double_cpu()) {
return opr->cpu_regnrLo();
#ifdef X86
} else if (opr->is_single_xmm()) {
return opr->fpu_regnr() + pd_first_xmm_reg;
} else if (opr->is_double_xmm()) {
return opr->fpu_regnrLo() + pd_first_xmm_reg;
#endif
} else if (opr->is_single_fpu()) {
return opr->fpu_regnr() + pd_first_fpu_reg;
} else if (opr->is_double_fpu()) {
return opr->fpu_regnrLo() + pd_first_fpu_reg;
} else {
ShouldNotReachHere();
return -1;
}
}
int LinearScan::reg_numHi(LIR_Opr opr) {
assert(opr->is_register(), "should not call this otherwise");
if (opr->is_virtual_register()) {
return -1;
} else if (opr->is_single_cpu()) {
return -1;
} else if (opr->is_double_cpu()) {
return opr->cpu_regnrHi();
#ifdef X86
} else if (opr->is_single_xmm()) {
return -1;
} else if (opr->is_double_xmm()) {
return -1;
#endif
} else if (opr->is_single_fpu()) {
return -1;
} else if (opr->is_double_fpu()) {
return opr->fpu_regnrHi() + pd_first_fpu_reg;
} else {
ShouldNotReachHere();
return -1;
}
}
// ********** functions for classification of intervals
bool LinearScan::is_precolored_interval(const Interval* i) {
return i->reg_num() < LinearScan::nof_regs;
}
bool LinearScan::is_virtual_interval(const Interval* i) {
return i->reg_num() >= LIR_OprDesc::vreg_base;
}
bool LinearScan::is_precolored_cpu_interval(const Interval* i) {
return i->reg_num() < LinearScan::nof_cpu_regs;
}
bool LinearScan::is_virtual_cpu_interval(const Interval* i) {
#if defined(__SOFTFP__) || defined(E500V2)
return i->reg_num() >= LIR_OprDesc::vreg_base;
#else
return i->reg_num() >= LIR_OprDesc::vreg_base && (i->type() != T_FLOAT && i->type() != T_DOUBLE);
#endif // __SOFTFP__ or E500V2
}
bool LinearScan::is_precolored_fpu_interval(const Interval* i) {
return i->reg_num() >= LinearScan::nof_cpu_regs && i->reg_num() < LinearScan::nof_regs;
}
bool LinearScan::is_virtual_fpu_interval(const Interval* i) {
#if defined(__SOFTFP__) || defined(E500V2)
return false;
#else
return i->reg_num() >= LIR_OprDesc::vreg_base && (i->type() == T_FLOAT || i->type() == T_DOUBLE);
#endif // __SOFTFP__ or E500V2
}
bool LinearScan::is_in_fpu_register(const Interval* i) {
// fixed intervals not needed for FPU stack allocation
return i->reg_num() >= nof_regs && pd_first_fpu_reg <= i->assigned_reg() && i->assigned_reg() <= pd_last_fpu_reg;
}
bool LinearScan::is_oop_interval(const Interval* i) {
// fixed intervals never contain oops
return i->reg_num() >= nof_regs && i->type() == T_OBJECT;
}
// ********** General helper functions
// compute next unused stack index that can be used for spilling
int LinearScan::allocate_spill_slot(bool double_word) {
int spill_slot;
if (double_word) {
if ((_max_spills & 1) == 1) {
// alignment of double-word values
// the hole because of the alignment is filled with the next single-word value
assert(_unused_spill_slot == -1, "wasting a spill slot");
_unused_spill_slot = _max_spills;
_max_spills++;
}
spill_slot = _max_spills;
_max_spills += 2;
} else if (_unused_spill_slot != -1) {
// re-use hole that was the result of a previous double-word alignment
spill_slot = _unused_spill_slot;
_unused_spill_slot = -1;
} else {
spill_slot = _max_spills;
_max_spills++;
}
int result = spill_slot + LinearScan::nof_regs + frame_map()->argcount();
// the class OopMapValue uses only 11 bits for storing the name of the
// oop location. So a stack slot bigger than 2^11 leads to an overflow
// that is not reported in product builds. Prevent this by checking the
// spill slot here (altough this value and the later used location name
// are slightly different)
if (result > 2000) {
bailout("too many stack slots used");
}
return result;
}
void LinearScan::assign_spill_slot(Interval* it) {
// assign the canonical spill slot of the parent (if a part of the interval
// is already spilled) or allocate a new spill slot
if (it->canonical_spill_slot() >= 0) {
it->assign_reg(it->canonical_spill_slot());
} else {
int spill = allocate_spill_slot(type2spill_size[it->type()] == 2);
it->set_canonical_spill_slot(spill);
it->assign_reg(spill);
}
}
void LinearScan::propagate_spill_slots() {
if (!frame_map()->finalize_frame(max_spills())) {
bailout("frame too large");
}
}
// create a new interval with a predefined reg_num
// (only used for parent intervals that are created during the building phase)
Interval* LinearScan::create_interval(int reg_num) {
assert(_intervals.at(reg_num) == NULL, "overwriting exisiting interval");
Interval* interval = new Interval(reg_num);
_intervals.at_put(reg_num, interval);
// assign register number for precolored intervals
if (reg_num < LIR_OprDesc::vreg_base) {
interval->assign_reg(reg_num);
}
return interval;
}
// assign a new reg_num to the interval and append it to the list of intervals
// (only used for child intervals that are created during register allocation)
void LinearScan::append_interval(Interval* it) {
it->set_reg_num(_intervals.length());
_intervals.append(it);
_new_intervals_from_allocation->append(it);
}
// copy the vreg-flags if an interval is split
void LinearScan::copy_register_flags(Interval* from, Interval* to) {
if (gen()->is_vreg_flag_set(from->reg_num(), LIRGenerator::byte_reg)) {
gen()->set_vreg_flag(to->reg_num(), LIRGenerator::byte_reg);
}
if (gen()->is_vreg_flag_set(from->reg_num(), LIRGenerator::callee_saved)) {
gen()->set_vreg_flag(to->reg_num(), LIRGenerator::callee_saved);
}
// Note: do not copy the must_start_in_memory flag because it is not necessary for child
// intervals (only the very beginning of the interval must be in memory)
}
// ********** spill move optimization
// eliminate moves from register to stack if stack slot is known to be correct
// called during building of intervals
void LinearScan::change_spill_definition_pos(Interval* interval, int def_pos) {
assert(interval->is_split_parent(), "can only be called for split parents");
switch (interval->spill_state()) {
case noDefinitionFound:
assert(interval->spill_definition_pos() == -1, "must no be set before");
interval->set_spill_definition_pos(def_pos);
interval->set_spill_state(oneDefinitionFound);
break;
case oneDefinitionFound:
assert(def_pos <= interval->spill_definition_pos(), "positions are processed in reverse order when intervals are created");
if (def_pos < interval->spill_definition_pos() - 2) {
// second definition found, so no spill optimization possible for this interval
interval->set_spill_state(noOptimization);
} else {
// two consecutive definitions (because of two-operand LIR form)
assert(block_of_op_with_id(def_pos) == block_of_op_with_id(interval->spill_definition_pos()), "block must be equal");
}
break;
case noOptimization:
// nothing to do
break;
default:
assert(false, "other states not allowed at this time");
}
}
// called during register allocation
void LinearScan::change_spill_state(Interval* interval, int spill_pos) {
switch (interval->spill_state()) {
case oneDefinitionFound: {
int def_loop_depth = block_of_op_with_id(interval->spill_definition_pos())->loop_depth();
int spill_loop_depth = block_of_op_with_id(spill_pos)->loop_depth();
if (def_loop_depth < spill_loop_depth) {
// the loop depth of the spilling position is higher then the loop depth
// at the definition of the interval -> move write to memory out of loop
// by storing at definitin of the interval
interval->set_spill_state(storeAtDefinition);
} else {
// the interval is currently spilled only once, so for now there is no
// reason to store the interval at the definition
interval->set_spill_state(oneMoveInserted);
}
break;
}
case oneMoveInserted: {
// the interval is spilled more then once, so it is better to store it to
// memory at the definition
interval->set_spill_state(storeAtDefinition);
break;
}
case storeAtDefinition:
case startInMemory:
case noOptimization:
case noDefinitionFound:
// nothing to do
break;
default:
assert(false, "other states not allowed at this time");
}
}
bool LinearScan::must_store_at_definition(const Interval* i) {
return i->is_split_parent() && i->spill_state() == storeAtDefinition;
}
// called once before asignment of register numbers
void LinearScan::eliminate_spill_moves() {
TIME_LINEAR_SCAN(timer_eliminate_spill_moves);
TRACE_LINEAR_SCAN(3, tty->print_cr("***** Eliminating unnecessary spill moves"));
// collect all intervals that must be stored after their definion.
// the list is sorted by Interval::spill_definition_pos
Interval* interval;
Interval* temp_list;
create_unhandled_lists(&interval, &temp_list, must_store_at_definition, NULL);
#ifdef ASSERT
Interval* prev = NULL;
Interval* temp = interval;
while (temp != Interval::end()) {
assert(temp->spill_definition_pos() > 0, "invalid spill definition pos");
if (prev != NULL) {
assert(temp->from() >= prev->from(), "intervals not sorted");
assert(temp->spill_definition_pos() >= prev->spill_definition_pos(), "when intervals are sorted by from, then they must also be sorted by spill_definition_pos");
}
assert(temp->canonical_spill_slot() >= LinearScan::nof_regs, "interval has no spill slot assigned");
assert(temp->spill_definition_pos() >= temp->from(), "invalid order");
assert(temp->spill_definition_pos() <= temp->from() + 2, "only intervals defined once at their start-pos can be optimized");
TRACE_LINEAR_SCAN(4, tty->print_cr("interval %d (from %d to %d) must be stored at %d", temp->reg_num(), temp->from(), temp->to(), temp->spill_definition_pos()));
temp = temp->next();
}
#endif
LIR_InsertionBuffer insertion_buffer;
int num_blocks = block_count();
for (int i = 0; i < num_blocks; i++) {
BlockBegin* block = block_at(i);
LIR_OpList* instructions = block->lir()->instructions_list();
int num_inst = instructions->length();
bool has_new = false;
// iterate all instructions of the block. skip the first because it is always a label
for (int j = 1; j < num_inst; j++) {
LIR_Op* op = instructions->at(j);
int op_id = op->id();
if (op_id == -1) {
// remove move from register to stack if the stack slot is guaranteed to be correct.
// only moves that have been inserted by LinearScan can be removed.
assert(op->code() == lir_move, "only moves can have a op_id of -1");
assert(op->as_Op1() != NULL, "move must be LIR_Op1");
assert(op->as_Op1()->result_opr()->is_virtual(), "LinearScan inserts only moves to virtual registers");
LIR_Op1* op1 = (LIR_Op1*)op;
Interval* interval = interval_at(op1->result_opr()->vreg_number());
if (interval->assigned_reg() >= LinearScan::nof_regs && interval->always_in_memory()) {
// move target is a stack slot that is always correct, so eliminate instruction
TRACE_LINEAR_SCAN(4, tty->print_cr("eliminating move from interval %d to %d", op1->in_opr()->vreg_number(), op1->result_opr()->vreg_number()));
instructions->at_put(j, NULL); // NULL-instructions are deleted by assign_reg_num
}
} else {
// insert move from register to stack just after the beginning of the interval
assert(interval == Interval::end() || interval->spill_definition_pos() >= op_id, "invalid order");
assert(interval == Interval::end() || (interval->is_split_parent() && interval->spill_state() == storeAtDefinition), "invalid interval");
while (interval != Interval::end() && interval->spill_definition_pos() == op_id) {
if (!has_new) {
// prepare insertion buffer (appended when all instructions of the block are processed)
insertion_buffer.init(block->lir());
has_new = true;
}
LIR_Opr from_opr = operand_for_interval(interval);
LIR_Opr to_opr = canonical_spill_opr(interval);
assert(from_opr->is_fixed_cpu() || from_opr->is_fixed_fpu(), "from operand must be a register");
assert(to_opr->is_stack(), "to operand must be a stack slot");
insertion_buffer.move(j, from_opr, to_opr);
TRACE_LINEAR_SCAN(4, tty->print_cr("inserting move after definition of interval %d to stack slot %d at op_id %d", interval->reg_num(), interval->canonical_spill_slot() - LinearScan::nof_regs, op_id));
interval = interval->next();
}
}
} // end of instruction iteration
if (has_new) {
block->lir()->append(&insertion_buffer);
}
} // end of block iteration
assert(interval == Interval::end(), "missed an interval");
}
// ********** Phase 1: number all instructions in all blocks
// Compute depth-first and linear scan block orders, and number LIR_Op nodes for linear scan.
void LinearScan::number_instructions() {
{
// dummy-timer to measure the cost of the timer itself
// (this time is then subtracted from all other timers to get the real value)
TIME_LINEAR_SCAN(timer_do_nothing);
}
TIME_LINEAR_SCAN(timer_number_instructions);
// Assign IDs to LIR nodes and build a mapping, lir_ops, from ID to LIR_Op node.
int num_blocks = block_count();
int num_instructions = 0;
int i;
for (i = 0; i < num_blocks; i++) {
num_instructions += block_at(i)->lir()->instructions_list()->length();
}
// initialize with correct length
_lir_ops = LIR_OpArray(num_instructions);
_block_of_op = BlockBeginArray(num_instructions);
int op_id = 0;
int idx = 0;
for (i = 0; i < num_blocks; i++) {
BlockBegin* block = block_at(i);
block->set_first_lir_instruction_id(op_id);
LIR_OpList* instructions = block->lir()->instructions_list();
int num_inst = instructions->length();
for (int j = 0; j < num_inst; j++) {
LIR_Op* op = instructions->at(j);
op->set_id(op_id);
_lir_ops.at_put(idx, op);
_block_of_op.at_put(idx, block);
assert(lir_op_with_id(op_id) == op, "must match");
idx++;
op_id += 2; // numbering of lir_ops by two
}
block->set_last_lir_instruction_id(op_id - 2);
}
assert(idx == num_instructions, "must match");
assert(idx * 2 == op_id, "must match");
_has_call = BitMap(num_instructions); _has_call.clear();
_has_info = BitMap(num_instructions); _has_info.clear();
}
// ********** Phase 2: compute local live sets separately for each block
// (sets live_gen and live_kill for each block)
void LinearScan::set_live_gen_kill(Value value, LIR_Op* op, BitMap& live_gen, BitMap& live_kill) {
LIR_Opr opr = value->operand();
Constant* con = value->as_Constant();
// check some asumptions about debug information
assert(!value->type()->is_illegal(), "if this local is used by the interpreter it shouldn't be of indeterminate type");
assert(con == NULL || opr->is_virtual() || opr->is_constant() || opr->is_illegal(), "asumption: Constant instructions have only constant operands");
assert(con != NULL || opr->is_virtual(), "asumption: non-Constant instructions have only virtual operands");
if ((con == NULL || con->is_pinned()) && opr->is_register()) {
assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
int reg = opr->vreg_number();
if (!live_kill.at(reg)) {
live_gen.set_bit(reg);
TRACE_LINEAR_SCAN(4, tty->print_cr(" Setting live_gen for value %c%d, LIR op_id %d, register number %d", value->type()->tchar(), value->id(), op->id(), reg));
}
}
}
void LinearScan::compute_local_live_sets() {
TIME_LINEAR_SCAN(timer_compute_local_live_sets);
int num_blocks = block_count();
int live_size = live_set_size();
bool local_has_fpu_registers = false;
int local_num_calls = 0;
LIR_OpVisitState visitor;
BitMap2D local_interval_in_loop = BitMap2D(_num_virtual_regs, num_loops());
local_interval_in_loop.clear();
// iterate all blocks
for (int i = 0; i < num_blocks; i++) {
BlockBegin* block = block_at(i);
BitMap live_gen(live_size); live_gen.clear();
BitMap live_kill(live_size); live_kill.clear();
if (block->is_set(BlockBegin::exception_entry_flag)) {
// Phi functions at the begin of an exception handler are
// implicitly defined (= killed) at the beginning of the block.
for_each_phi_fun(block, phi,
live_kill.set_bit(phi->operand()->vreg_number())
);
}
LIR_OpList* instructions = block->lir()->instructions_list();
int num_inst = instructions->length();
// iterate all instructions of the block. skip the first because it is always a label
assert(visitor.no_operands(instructions->at(0)), "first operation must always be a label");
for (int j = 1; j < num_inst; j++) {
LIR_Op* op = instructions->at(j);
// visit operation to collect all operands
visitor.visit(op);
if (visitor.has_call()) {
_has_call.set_bit(op->id() >> 1);
local_num_calls++;
}
if (visitor.info_count() > 0) {
_has_info.set_bit(op->id() >> 1);
}
// iterate input operands of instruction
int k, n, reg;
n = visitor.opr_count(LIR_OpVisitState::inputMode);
for (k = 0; k < n; k++) {
LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::inputMode, k);
assert(opr->is_register(), "visitor should only return register operands");
if (opr->is_virtual_register()) {
assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
reg = opr->vreg_number();
if (!live_kill.at(reg)) {
live_gen.set_bit(reg);
TRACE_LINEAR_SCAN(4, tty->print_cr(" Setting live_gen for register %d at instruction %d", reg, op->id()));
}
if (block->loop_index() >= 0) {
local_interval_in_loop.set_bit(reg, block->loop_index());
}
local_has_fpu_registers = local_has_fpu_registers || opr->is_virtual_fpu();
}
#ifdef ASSERT
// fixed intervals are never live at block boundaries, so
// they need not be processed in live sets.
// this is checked by these assertions to be sure about it.
// the entry block may have incoming values in registers, which is ok.
if (!opr->is_virtual_register() && block != ir()->start()) {
reg = reg_num(opr);
if (is_processed_reg_num(reg)) {
assert(live_kill.at(reg), "using fixed register that is not defined in this block");
}
reg = reg_numHi(opr);
if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
assert(live_kill.at(reg), "using fixed register that is not defined in this block");
}
}
#endif
}
// Add uses of live locals from interpreter's point of view for proper debug information generation
n = visitor.info_count();
for (k = 0; k < n; k++) {
CodeEmitInfo* info = visitor.info_at(k);
ValueStack* stack = info->stack();
for_each_state_value(stack, value,
set_live_gen_kill(value, op, live_gen, live_kill)
);
}
// iterate temp operands of instruction
n = visitor.opr_count(LIR_OpVisitState::tempMode);
for (k = 0; k < n; k++) {
LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::tempMode, k);
assert(opr->is_register(), "visitor should only return register operands");
if (opr->is_virtual_register()) {
assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
reg = opr->vreg_number();
live_kill.set_bit(reg);
if (block->loop_index() >= 0) {
local_interval_in_loop.set_bit(reg, block->loop_index());
}
local_has_fpu_registers = local_has_fpu_registers || opr->is_virtual_fpu();
}
#ifdef ASSERT
// fixed intervals are never live at block boundaries, so
// they need not be processed in live sets
// process them only in debug mode so that this can be checked
if (!opr->is_virtual_register()) {
reg = reg_num(opr);
if (is_processed_reg_num(reg)) {
live_kill.set_bit(reg_num(opr));
}
reg = reg_numHi(opr);
if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
live_kill.set_bit(reg);
}
}
#endif
}
// iterate output operands of instruction
n = visitor.opr_count(LIR_OpVisitState::outputMode);
for (k = 0; k < n; k++) {
LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::outputMode, k);
assert(opr->is_register(), "visitor should only return register operands");
if (opr->is_virtual_register()) {
assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
reg = opr->vreg_number();
live_kill.set_bit(reg);
if (block->loop_index() >= 0) {
local_interval_in_loop.set_bit(reg, block->loop_index());
}
local_has_fpu_registers = local_has_fpu_registers || opr->is_virtual_fpu();
}
#ifdef ASSERT
// fixed intervals are never live at block boundaries, so
// they need not be processed in live sets
// process them only in debug mode so that this can be checked
if (!opr->is_virtual_register()) {
reg = reg_num(opr);
if (is_processed_reg_num(reg)) {
live_kill.set_bit(reg_num(opr));
}
reg = reg_numHi(opr);
if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
live_kill.set_bit(reg);
}
}
#endif
}
} // end of instruction iteration
block->set_live_gen (live_gen);
block->set_live_kill(live_kill);
block->set_live_in (BitMap(live_size)); block->live_in().clear();
block->set_live_out (BitMap(live_size)); block->live_out().clear();
TRACE_LINEAR_SCAN(4, tty->print("live_gen B%d ", block->block_id()); print_bitmap(block->live_gen()));
TRACE_LINEAR_SCAN(4, tty->print("live_kill B%d ", block->block_id()); print_bitmap(block->live_kill()));
} // end of block iteration
// propagate local calculated information into LinearScan object
_has_fpu_registers = local_has_fpu_registers;
compilation()->set_has_fpu_code(local_has_fpu_registers);
_num_calls = local_num_calls;
_interval_in_loop = local_interval_in_loop;
}
// ********** Phase 3: perform a backward dataflow analysis to compute global live sets
// (sets live_in and live_out for each block)
void LinearScan::compute_global_live_sets() {
TIME_LINEAR_SCAN(timer_compute_global_live_sets);
int num_blocks = block_count();
bool change_occurred;
bool change_occurred_in_block;
int iteration_count = 0;
BitMap live_out(live_set_size()); live_out.clear(); // scratch set for calculations
// Perform a backward dataflow analysis to compute live_out and live_in for each block.
// The loop is executed until a fixpoint is reached (no changes in an iteration)
// Exception handlers must be processed because not all live values are
// present in the state array, e.g. because of global value numbering
do {
change_occurred = false;
// iterate all blocks in reverse order
for (int i = num_blocks - 1; i >= 0; i--) {
BlockBegin* block = block_at(i);
change_occurred_in_block = false;
// live_out(block) is the union of live_in(sux), for successors sux of block
int n = block->number_of_sux();
int e = block->number_of_exception_handlers();
if (n + e > 0) {
// block has successors
if (n > 0) {
live_out.set_from(block->sux_at(0)->live_in());
for (int j = 1; j < n; j++) {
live_out.set_union(block->sux_at(j)->live_in());
}
} else {
live_out.clear();
}
for (int j = 0; j < e; j++) {
live_out.set_union(block->exception_handler_at(j)->live_in());
}
if (!block->live_out().is_same(live_out)) {
// A change occurred. Swap the old and new live out sets to avoid copying.
BitMap temp = block->live_out();
block->set_live_out(live_out);
live_out = temp;
change_occurred = true;
change_occurred_in_block = true;
}
}
if (iteration_count == 0 || change_occurred_in_block) {
// live_in(block) is the union of live_gen(block) with (live_out(block) & !live_kill(block))
// note: live_in has to be computed only in first iteration or if live_out has changed!
BitMap live_in = block->live_in();
live_in.set_from(block->live_out());
live_in.set_difference(block->live_kill());
live_in.set_union(block->live_gen());
}
#ifndef PRODUCT
if (TraceLinearScanLevel >= 4) {
char c = ' ';
if (iteration_count == 0 || change_occurred_in_block) {
c = '*';
}
tty->print("(%d) live_in%c B%d ", iteration_count, c, block->block_id()); print_bitmap(block->live_in());
tty->print("(%d) live_out%c B%d ", iteration_count, c, block->block_id()); print_bitmap(block->live_out());
}
#endif
}
iteration_count++;
if (change_occurred && iteration_count > 50) {
BAILOUT("too many iterations in compute_global_live_sets");
}
} while (change_occurred);
#ifdef ASSERT
// check that fixed intervals are not live at block boundaries
// (live set must be empty at fixed intervals)
for (int i = 0; i < num_blocks; i++) {
BlockBegin* block = block_at(i);
for (int j = 0; j < LIR_OprDesc::vreg_base; j++) {
assert(block->live_in().at(j) == false, "live_in set of fixed register must be empty");
assert(block->live_out().at(j) == false, "live_out set of fixed register must be empty");
assert(block->live_gen().at(j) == false, "live_gen set of fixed register must be empty");
}
}
#endif
// check that the live_in set of the first block is empty
BitMap live_in_args(ir()->start()->live_in().size());
live_in_args.clear();
if (!ir()->start()->live_in().is_same(live_in_args)) {
#ifdef ASSERT
tty->print_cr("Error: live_in set of first block must be empty (when this fails, virtual registers are used before they are defined)");
tty->print_cr("affected registers:");
print_bitmap(ir()->start()->live_in());
// print some additional information to simplify debugging
for (unsigned int i = 0; i < ir()->start()->live_in().size(); i++) {
if (ir()->start()->live_in().at(i)) {
Instruction* instr = gen()->instruction_for_vreg(i);
tty->print_cr("* vreg %d (HIR instruction %c%d)", i, instr == NULL ? ' ' : instr->type()->tchar(), instr == NULL ? 0 : instr->id());
for (int j = 0; j < num_blocks; j++) {
BlockBegin* block = block_at(j);
if (block->live_gen().at(i)) {
tty->print_cr(" used in block B%d", block->block_id());
}
if (block->live_kill().at(i)) {
tty->print_cr(" defined in block B%d", block->block_id());
}
}
}
}
#endif
// when this fails, virtual registers are used before they are defined.
assert(false, "live_in set of first block must be empty");
// bailout of if this occurs in product mode.
bailout("live_in set of first block not empty");
}
}
// ********** Phase 4: build intervals
// (fills the list _intervals)
void LinearScan::add_use(Value value, int from, int to, IntervalUseKind use_kind) {
assert(!value->type()->is_illegal(), "if this value is used by the interpreter it shouldn't be of indeterminate type");
LIR_Opr opr = value->operand();
Constant* con = value->as_Constant();
if ((con == NULL || con->is_pinned()) && opr->is_register()) {
assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
add_use(opr, from, to, use_kind);
}
}
void LinearScan::add_def(LIR_Opr opr, int def_pos, IntervalUseKind use_kind) {
TRACE_LINEAR_SCAN(2, tty->print(" def "); opr->print(tty); tty->print_cr(" def_pos %d (%d)", def_pos, use_kind));
assert(opr->is_register(), "should not be called otherwise");
if (opr->is_virtual_register()) {
assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
add_def(opr->vreg_number(), def_pos, use_kind, opr->type_register());
} else {
int reg = reg_num(opr);
if (is_processed_reg_num(reg)) {
add_def(reg, def_pos, use_kind, opr->type_register());
}
reg = reg_numHi(opr);
if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
add_def(reg, def_pos, use_kind, opr->type_register());
}
}
}
void LinearScan::add_use(LIR_Opr opr, int from, int to, IntervalUseKind use_kind) {
TRACE_LINEAR_SCAN(2, tty->print(" use "); opr->print(tty); tty->print_cr(" from %d to %d (%d)", from, to, use_kind));
assert(opr->is_register(), "should not be called otherwise");
if (opr->is_virtual_register()) {
assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
add_use(opr->vreg_number(), from, to, use_kind, opr->type_register());
} else {
int reg = reg_num(opr);
if (is_processed_reg_num(reg)) {
add_use(reg, from, to, use_kind, opr->type_register());
}
reg = reg_numHi(opr);
if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
add_use(reg, from, to, use_kind, opr->type_register());
}
}
}
void LinearScan::add_temp(LIR_Opr opr, int temp_pos, IntervalUseKind use_kind) {
TRACE_LINEAR_SCAN(2, tty->print(" temp "); opr->print(tty); tty->print_cr(" temp_pos %d (%d)", temp_pos, use_kind));
assert(opr->is_register(), "should not be called otherwise");
if (opr->is_virtual_register()) {
assert(reg_num(opr) == opr->vreg_number() && !is_valid_reg_num(reg_numHi(opr)), "invalid optimization below");
add_temp(opr->vreg_number(), temp_pos, use_kind, opr->type_register());
} else {
int reg = reg_num(opr);
if (is_processed_reg_num(reg)) {
add_temp(reg, temp_pos, use_kind, opr->type_register());
}
reg = reg_numHi(opr);
if (is_valid_reg_num(reg) && is_processed_reg_num(reg)) {
add_temp(reg, temp_pos, use_kind, opr->type_register());
}
}
}
void LinearScan::add_def(int reg_num, int def_pos, IntervalUseKind use_kind, BasicType type) {
Interval* interval = interval_at(reg_num);
if (interval != NULL) {
assert(interval->reg_num() == reg_num, "wrong interval");
if (type != T_ILLEGAL) {
interval->set_type(type);
}
Range* r = interval->first();
if (r->from() <= def_pos) {
// Update the starting point (when a range is first created for a use, its
// start is the beginning of the current block until a def is encountered.)
r->set_from(def_pos);
interval->add_use_pos(def_pos, use_kind);
} else {
// Dead value - make vacuous interval
// also add use_kind for dead intervals
interval->add_range(def_pos, def_pos + 1);
interval->add_use_pos(def_pos, use_kind);
TRACE_LINEAR_SCAN(2, tty->print_cr("Warning: def of reg %d at %d occurs without use", reg_num, def_pos));
}
} else {
// Dead value - make vacuous interval
// also add use_kind for dead intervals
interval = create_interval(reg_num);
if (type != T_ILLEGAL) {
interval->set_type(type);
}
interval->add_range(def_pos, def_pos + 1);
interval->add_use_pos(def_pos, use_kind);
TRACE_LINEAR_SCAN(2, tty->print_cr("Warning: dead value %d at %d in live intervals", reg_num, def_pos));
}
change_spill_definition_pos(interval, def_pos);
if (use_kind == noUse && interval->spill_state() <= startInMemory) {
// detection of method-parameters and roundfp-results
// TODO: move this directly to position where use-kind is computed
interval->set_spill_state(startInMemory);
}
}
void LinearScan::add_use(int reg_num, int from, int to, IntervalUseKind use_kind, BasicType type) {
Interval* interval = interval_at(reg_num);
if (interval == NULL) {
interval = create_interval(reg_num);
}
assert(interval->reg_num() == reg_num, "wrong interval");
if (type != T_ILLEGAL) {
interval->set_type(type);
}
interval->add_range(from, to);
interval->add_use_pos(to, use_kind);
}
void LinearScan::add_temp(int reg_num, int temp_pos, IntervalUseKind use_kind, BasicType type) {
Interval* interval = interval_at(reg_num);
if (interval == NULL) {
interval = create_interval(reg_num);
}
assert(interval->reg_num() == reg_num, "wrong interval");
if (type != T_ILLEGAL) {
interval->set_type(type);
}
interval->add_range(temp_pos, temp_pos + 1);
interval->add_use_pos(temp_pos, use_kind);
}
// the results of this functions are used for optimizing spilling and reloading
// if the functions return shouldHaveRegister and the interval is spilled,
// it is not reloaded to a register.
IntervalUseKind LinearScan::use_kind_of_output_operand(LIR_Op* op, LIR_Opr opr) {
if (op->code() == lir_move) {
assert(op->as_Op1() != NULL, "lir_move must be LIR_Op1");
LIR_Op1* move = (LIR_Op1*)op;
LIR_Opr res = move->result_opr();
bool result_in_memory = res->is_virtual() && gen()->is_vreg_flag_set(res->vreg_number(), LIRGenerator::must_start_in_memory);
if (result_in_memory) {
// Begin of an interval with must_start_in_memory set.
// This interval will always get a stack slot first, so return noUse.
return noUse;
} else if (move->in_opr()->is_stack()) {
// method argument (condition must be equal to handle_method_arguments)
return noUse;
} else if (move->in_opr()->is_register() && move->result_opr()->is_register()) {
// Move from register to register
if (block_of_op_with_id(op->id())->is_set(BlockBegin::osr_entry_flag)) {
// special handling of phi-function moves inside osr-entry blocks
// input operand must have a register instead of output operand (leads to better register allocation)
return shouldHaveRegister;
}
}
}
if (opr->is_virtual() &&
gen()->is_vreg_flag_set(opr->vreg_number(), LIRGenerator::must_start_in_memory)) {
// result is a stack-slot, so prevent immediate reloading
return noUse;
}
// all other operands require a register
return mustHaveRegister;
}
IntervalUseKind LinearScan::use_kind_of_input_operand(LIR_Op* op, LIR_Opr opr) {
if (op->code() == lir_move) {
assert(op->as_Op1() != NULL, "lir_move must be LIR_Op1");
LIR_Op1* move = (LIR_Op1*)op;
LIR_Opr res = move->result_opr();
bool result_in_memory = res->is_virtual() && gen()->is_vreg_flag_set(res->vreg_number(), LIRGenerator::must_start_in_memory);
if (result_in_memory) {
// Move to an interval with must_start_in_memory set.
// To avoid moves from stack to stack (not allowed) force the input operand to a register
return mustHaveRegister;
} else if (move->in_opr()->is_register() && move->result_opr()->is_register()) {
// Move from register to register
if (block_of_op_with_id(op->id())->is_set(BlockBegin::osr_entry_flag)) {
// special handling of phi-function moves inside osr-entry blocks
// input operand must have a register instead of output operand (leads to better register allocation)
return mustHaveRegister;
}
// The input operand is not forced to a register (moves from stack to register are allowed),
// but it is faster if the input operand is in a register
return shouldHaveRegister;
}
}
#ifdef X86
if (op->code() == lir_cmove) {
// conditional moves can handle stack operands
assert(op->result_opr()->is_register(), "result must always be in a register");
return shouldHaveRegister;
}
// optimizations for second input operand of arithmehtic operations on Intel
// this operand is allowed to be on the stack in some cases
BasicType opr_type = opr->type_register();
if (opr_type == T_FLOAT || opr_type == T_DOUBLE) {
if ((UseSSE == 1 && opr_type == T_FLOAT) || UseSSE >= 2) {
// SSE float instruction (T_DOUBLE only supported with SSE2)
switch (op->code()) {
case lir_cmp:
case lir_add:
case lir_sub:
case lir_mul:
case lir_div:
{
assert(op->as_Op2() != NULL, "must be LIR_Op2");
LIR_Op2* op2 = (LIR_Op2*)op;
if (op2->in_opr1() != op2->in_opr2() && op2->in_opr2() == opr) {
assert((op2->result_opr()->is_register() || op->code() == lir_cmp) && op2->in_opr1()->is_register(), "cannot mark second operand as stack if others are not in register");
return shouldHaveRegister;
}
}
}
} else {
// FPU stack float instruction
switch (op->code()) {
case lir_add:
case lir_sub:
case lir_mul:
case lir_div:
{
assert(op->as_Op2() != NULL, "must be LIR_Op2");
LIR_Op2* op2 = (LIR_Op2*)op;
if (op2->in_opr1() != op2->in_opr2() && op2->in_opr2() == opr) {
assert((op2->result_opr()->is_register() || op->code() == lir_cmp) && op2->in_opr1()->is_register(), "cannot mark second operand as stack if others are not in register");
return shouldHaveRegister;
}
}
}
}
// We want to sometimes use logical operations on pointers, in particular in GC barriers.
// Since 64bit logical operations do not current support operands on stack, we have to make sure
// T_OBJECT doesn't get spilled along with T_LONG.
} else if (opr_type != T_LONG LP64_ONLY(&& opr_type != T_OBJECT)) {
// integer instruction (note: long operands must always be in register)
switch (op->code()) {
case lir_cmp:
case lir_add:
case lir_sub:
case lir_logic_and:
case lir_logic_or:
case lir_logic_xor:
{
assert(op->as_Op2() != NULL, "must be LIR_Op2");
LIR_Op2* op2 = (LIR_Op2*)op;
if (op2->in_opr1() != op2->in_opr2() && op2->in_opr2() == opr) {
assert((op2->result_opr()->is_register() || op->code() == lir_cmp) && op2->in_opr1()->is_register(), "cannot mark second operand as stack if others are not in register");
return shouldHaveRegister;
}
}
}
}
#endif // X86
// all other operands require a register
return mustHaveRegister;
}
void LinearScan::handle_method_arguments(LIR_Op* op) {
// special handling for method arguments (moves from stack to virtual register):
// the interval gets no register assigned, but the stack slot.
// it is split before the first use by the register allocator.
if (op->code() == lir_move) {
assert(op->as_Op1() != NULL, "must be LIR_Op1");
LIR_Op1* move = (LIR_Op1*)op;
if (move->in_opr()->is_stack()) {
#ifdef ASSERT
int arg_size = compilation()->method()->arg_size();
LIR_Opr o = move->in_opr();
if (o->is_single_stack()) {
assert(o->single_stack_ix() >= 0 && o->single_stack_ix() < arg_size, "out of range");
} else if (o->is_double_stack()) {
assert(o->double_stack_ix() >= 0 && o->double_stack_ix() < arg_size, "out of range");
} else {
ShouldNotReachHere();
}
assert(move->id() > 0, "invalid id");
assert(block_of_op_with_id(move->id())->number_of_preds() == 0, "move from stack must be in first block");
assert(move->result_opr()->is_virtual(), "result of move must be a virtual register");
TRACE_LINEAR_SCAN(4, tty->print_cr("found move from stack slot %d to vreg %d", o->is_single_stack() ? o->single_stack_ix() : o->double_stack_ix(), reg_num(move->result_opr())));
#endif
Interval* interval = interval_at(reg_num(move->result_opr()));
int stack_slot = LinearScan::nof_regs + (move->in_opr()->is_single_stack() ? move->in_opr()->single_stack_ix() : move->in_opr()->double_stack_ix());
interval->set_canonical_spill_slot(stack_slot);
interval->assign_reg(stack_slot);
}
}
}
void LinearScan::handle_doubleword_moves(LIR_Op* op) {
// special handling for doubleword move from memory to register:
// in this case the registers of the input address and the result
// registers must not overlap -> add a temp range for the input registers
if (op->code() == lir_move) {
assert(op->as_Op1() != NULL, "must be LIR_Op1");
LIR_Op1* move = (LIR_Op1*)op;
if (move->result_opr()->is_double_cpu() && move->in_opr()->is_pointer()) {
LIR_Address* address = move->in_opr()->as_address_ptr();
if (address != NULL) {
if (address->base()->is_valid()) {
add_temp(address->base(), op->id(), noUse);
}
if (address->index()->is_valid()) {
add_temp(address->index(), op->id(), noUse);
}
}
}
}
}
void LinearScan::add_register_hints(LIR_Op* op) {
switch (op->code()) {
case lir_move: // fall through
case lir_convert: {
assert(op->as_Op1() != NULL, "lir_move, lir_convert must be LIR_Op1");
LIR_Op1* move = (LIR_Op1*)op;
LIR_Opr move_from = move->in_opr();
LIR_Opr move_to = move->result_opr();
if (move_to->is_register() && move_from->is_register()) {
Interval* from = interval_at(reg_num(move_from));
Interval* to = interval_at(reg_num(move_to));
if (from != NULL && to != NULL) {
to->set_register_hint(from);
TRACE_LINEAR_SCAN(4, tty->print_cr("operation at op_id %d: added hint from interval %d to %d", move->id(), from->reg_num(), to->reg_num()));
}
}
break;
}
case lir_cmove: {
assert(op->as_Op2() != NULL, "lir_cmove must be LIR_Op2");
LIR_Op2* cmove = (LIR_Op2*)op;
LIR_Opr move_from = cmove->in_opr1();
LIR_Opr move_to = cmove->result_opr();
if (move_to->is_register() && move_from->is_register()) {
Interval* from = interval_at(reg_num(move_from));
Interval* to = interval_at(reg_num(move_to));
if (from != NULL && to != NULL) {
to->set_register_hint(from);
TRACE_LINEAR_SCAN(4, tty->print_cr("operation at op_id %d: added hint from interval %d to %d", cmove->id(), from->reg_num(), to->reg_num()));
}
}
break;
}
}
}
void LinearScan::build_intervals() {
TIME_LINEAR_SCAN(timer_build_intervals);
// initialize interval list with expected number of intervals
// (32 is added to have some space for split children without having to resize the list)
_intervals = IntervalList(num_virtual_regs() + 32);
// initialize all slots that are used by build_intervals
_intervals.at_put_grow(num_virtual_regs() - 1, NULL, NULL);
// create a list with all caller-save registers (cpu, fpu, xmm)
// when an instruction is a call, a temp range is created for all these registers
int num_caller_save_registers = 0;
int caller_save_registers[LinearScan::nof_regs];
int i;
for (i = 0; i < FrameMap::nof_caller_save_cpu_regs(); i++) {
LIR_Opr opr = FrameMap::caller_save_cpu_reg_at(i);
assert(opr->is_valid() && opr->is_register(), "FrameMap should not return invalid operands");
assert(reg_numHi(opr) == -1, "missing addition of range for hi-register");
caller_save_registers[num_caller_save_registers++] = reg_num(opr);
}
// temp ranges for fpu registers are only created when the method has
// virtual fpu operands. Otherwise no allocation for fpu registers is
// perfomed and so the temp ranges would be useless
if (has_fpu_registers()) {
#ifdef X86
if (UseSSE < 2) {
#endif
for (i = 0; i < FrameMap::nof_caller_save_fpu_regs; i++) {
LIR_Opr opr = FrameMap::caller_save_fpu_reg_at(i);
assert(opr->is_valid() && opr->is_register(), "FrameMap should not return invalid operands");
assert(reg_numHi(opr) == -1, "missing addition of range for hi-register");
caller_save_registers[num_caller_save_registers++] = reg_num(opr);
}
#ifdef X86
}
if (UseSSE > 0) {
for (i = 0; i < FrameMap::nof_caller_save_xmm_regs; i++) {
LIR_Opr opr = FrameMap::caller_save_xmm_reg_at(i);
assert(opr->is_valid() && opr->is_register(), "FrameMap should not return invalid operands");
assert(reg_numHi(opr) == -1, "missing addition of range for hi-register");
caller_save_registers[num_caller_save_registers++] = reg_num(opr);
}
}
#endif
}
assert(num_caller_save_registers <= LinearScan::nof_regs, "out of bounds");
LIR_OpVisitState visitor;
// iterate all blocks in reverse order
for (i = block_count() - 1; i >= 0; i--) {
BlockBegin* block = block_at(i);
LIR_OpList* instructions = block->lir()->instructions_list();
int block_from = block->first_lir_instruction_id();
int block_to = block->last_lir_instruction_id();
assert(block_from == instructions->at(0)->id(), "must be");
assert(block_to == instructions->at(instructions->length() - 1)->id(), "must be");
// Update intervals for registers live at the end of this block;
BitMap live = block->live_out();
int size = (int)live.size();
for (int number = (int)live.get_next_one_offset(0, size); number < size; number = (int)live.get_next_one_offset(number + 1, size)) {
assert(live.at(number), "should not stop here otherwise");
assert(number >= LIR_OprDesc::vreg_base, "fixed intervals must not be live on block bounds");
TRACE_LINEAR_SCAN(2, tty->print_cr("live in %d to %d", number, block_to + 2));
add_use(number, block_from, block_to + 2, noUse, T_ILLEGAL);
// add special use positions for loop-end blocks when the
// interval is used anywhere inside this loop. It's possible
// that the block was part of a non-natural loop, so it might
// have an invalid loop index.
if (block->is_set(BlockBegin::linear_scan_loop_end_flag) &&
block->loop_index() != -1 &&
is_interval_in_loop(number, block->loop_index())) {
interval_at(number)->add_use_pos(block_to + 1, loopEndMarker);
}
}
// iterate all instructions of the block in reverse order.
// skip the first instruction because it is always a label
// definitions of intervals are processed before uses
assert(visitor.no_operands(instructions->at(0)), "first operation must always be a label");
for (int j = instructions->length() - 1; j >= 1; j--) {
LIR_Op* op = instructions->at(j);
int op_id = op->id();
// visit operation to collect all operands
visitor.visit(op);
// add a temp range for each register if operation destroys caller-save registers
if (visitor.has_call()) {
for (int k = 0; k < num_caller_save_registers; k++) {
add_temp(caller_save_registers[k], op_id, noUse, T_ILLEGAL);
}
TRACE_LINEAR_SCAN(4, tty->print_cr("operation destroys all caller-save registers"));
}
// Add any platform dependent temps
pd_add_temps(op);
// visit definitions (output and temp operands)
int k, n;
n = visitor.opr_count(LIR_OpVisitState::outputMode);
for (k = 0; k < n; k++) {
LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::outputMode, k);
assert(opr->is_register(), "visitor should only return register operands");
add_def(opr, op_id, use_kind_of_output_operand(op, opr));
}
n = visitor.opr_count(LIR_OpVisitState::tempMode);
for (k = 0; k < n; k++) {
LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::tempMode, k);
assert(opr->is_register(), "visitor should only return register operands");
add_temp(opr, op_id, mustHaveRegister);
}
// visit uses (input operands)
n = visitor.opr_count(LIR_OpVisitState::inputMode);
for (k = 0; k < n; k++) {
LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::inputMode, k);
assert(opr->is_register(), "visitor should only return register operands");
add_use(opr, block_from, op_id, use_kind_of_input_operand(op, opr));
}
// Add uses of live locals from interpreter's point of view for proper
// debug information generation
// Treat these operands as temp values (if the life range is extended
// to a call site, the value would be in a register at the call otherwise)
n = visitor.info_count();
for (k = 0; k < n; k++) {
CodeEmitInfo* info = visitor.info_at(k);
ValueStack* stack = info->stack();
for_each_state_value(stack, value,
add_use(value, block_from, op_id + 1, noUse);
);
}
// special steps for some instructions (especially moves)
handle_method_arguments(op);
handle_doubleword_moves(op);
add_register_hints(op);
} // end of instruction iteration
} // end of block iteration
// add the range [0, 1[ to all fixed intervals
// -> the register allocator need not handle unhandled fixed intervals
for (int n = 0; n < LinearScan::nof_regs; n++) {
Interval* interval = interval_at(n);
if (interval != NULL) {
interval->add_range(0, 1);
}
}
}
// ********** Phase 5: actual register allocation
int LinearScan::interval_cmp(Interval** a, Interval** b) {
if (*a != NULL) {
if (*b != NULL) {
return (*a)->from() - (*b)->from();
} else {
return -1;
}
} else {
if (*b != NULL) {
return 1;
} else {
return 0;
}
}
}
#ifndef PRODUCT
bool LinearScan::is_sorted(IntervalArray* intervals) {
int from = -1;
int i, j;
for (i = 0; i < intervals->length(); i ++) {
Interval* it = intervals->at(i);
if (it != NULL) {
if (from > it->from()) {
assert(false, "");
return false;
}
from = it->from();
}
}
// check in both directions if sorted list and unsorted list contain same intervals
for (i = 0; i < interval_count(); i++) {
if (interval_at(i) != NULL) {
int num_found = 0;
for (j = 0; j < intervals->length(); j++) {
if (interval_at(i) == intervals->at(j)) {
num_found++;
}
}
assert(num_found == 1, "lists do not contain same intervals");
}
}
for (j = 0; j < intervals->length(); j++) {
int num_found = 0;
for (i = 0; i < interval_count(); i++) {
if (interval_at(i) == intervals->at(j)) {
num_found++;
}
}
assert(num_found == 1, "lists do not contain same intervals");
}
return true;
}
#endif
void LinearScan::add_to_list(Interval** first, Interval** prev, Interval* interval) {
if (*prev != NULL) {
(*prev)->set_next(interval);
} else {
*first = interval;
}
*prev = interval;
}
void LinearScan::create_unhandled_lists(Interval** list1, Interval** list2, bool (is_list1)(const Interval* i), bool (is_list2)(const Interval* i)) {
assert(is_sorted(_sorted_intervals), "interval list is not sorted");
*list1 = *list2 = Interval::end();
Interval* list1_prev = NULL;
Interval* list2_prev = NULL;
Interval* v;
const int n = _sorted_intervals->length();
for (int i = 0; i < n; i++) {
v = _sorted_intervals->at(i);
if (v == NULL) continue;
if (is_list1(v)) {
add_to_list(list1, &list1_prev, v);
} else if (is_list2 == NULL || is_list2(v)) {
add_to_list(list2, &list2_prev, v);
}
}
if (list1_prev != NULL) list1_prev->set_next(Interval::end());
if (list2_prev != NULL) list2_prev->set_next(Interval::end());
assert(list1_prev == NULL || list1_prev->next() == Interval::end(), "linear list ends not with sentinel");
assert(list2_prev == NULL || list2_prev->next() == Interval::end(), "linear list ends not with sentinel");
}
void LinearScan::sort_intervals_before_allocation() {
TIME_LINEAR_SCAN(timer_sort_intervals_before);
if (_needs_full_resort) {
// There is no known reason why this should occur but just in case...
assert(false, "should never occur");
// Re-sort existing interval list because an Interval::from() has changed
_sorted_intervals->sort(interval_cmp);
_needs_full_resort = false;
}
IntervalList* unsorted_list = &_intervals;
int unsorted_len = unsorted_list->length();
int sorted_len = 0;
int unsorted_idx;
int sorted_idx = 0;
int sorted_from_max = -1;
// calc number of items for sorted list (sorted list must not contain NULL values)
for (unsorted_idx = 0; unsorted_idx < unsorted_len; unsorted_idx++) {
if (unsorted_list->at(unsorted_idx) != NULL) {
sorted_len++;
}
}
IntervalArray* sorted_list = new IntervalArray(sorted_len);
// special sorting algorithm: the original interval-list is almost sorted,
// only some intervals are swapped. So this is much faster than a complete QuickSort
for (unsorted_idx = 0; unsorted_idx < unsorted_len; unsorted_idx++) {
Interval* cur_interval = unsorted_list->at(unsorted_idx);
if (cur_interval != NULL) {
int cur_from = cur_interval->from();
if (sorted_from_max <= cur_from) {
sorted_list->at_put(sorted_idx++, cur_interval);
sorted_from_max = cur_interval->from();
} else {
// the asumption that the intervals are already sorted failed,
// so this interval must be sorted in manually
int j;
for (j = sorted_idx - 1; j >= 0 && cur_from < sorted_list->at(j)->from(); j--) {
sorted_list->at_put(j + 1, sorted_list->at(j));
}
sorted_list->at_put(j + 1, cur_interval);
sorted_idx++;
}
}
}
_sorted_intervals = sorted_list;
assert(is_sorted(_sorted_intervals), "intervals unsorted");
}
void LinearScan::sort_intervals_after_allocation() {
TIME_LINEAR_SCAN(timer_sort_intervals_after);
if (_needs_full_resort) {
// Re-sort existing interval list because an Interval::from() has changed
_sorted_intervals->sort(interval_cmp);
_needs_full_resort = false;
}
IntervalArray* old_list = _sorted_intervals;
IntervalList* new_list = _new_intervals_from_allocation;
int old_len = old_list->length();
int new_len = new_list->length();
if (new_len == 0) {
// no intervals have been added during allocation, so sorted list is already up to date
assert(is_sorted(_sorted_intervals), "intervals unsorted");
return;
}
// conventional sort-algorithm for new intervals
new_list->sort(interval_cmp);
// merge old and new list (both already sorted) into one combined list
IntervalArray* combined_list = new IntervalArray(old_len + new_len);
int old_idx = 0;
int new_idx = 0;
while (old_idx + new_idx < old_len + new_len) {
if (new_idx >= new_len || (old_idx < old_len && old_list->at(old_idx)->from() <= new_list->at(new_idx)->from())) {
combined_list->at_put(old_idx + new_idx, old_list->at(old_idx));
old_idx++;
} else {
combined_list->at_put(old_idx + new_idx, new_list->at(new_idx));
new_idx++;
}
}
_sorted_intervals = combined_list;
assert(is_sorted(_sorted_intervals), "intervals unsorted");
}
void LinearScan::allocate_registers() {
TIME_LINEAR_SCAN(timer_allocate_registers);
Interval* precolored_cpu_intervals, *not_precolored_cpu_intervals;
Interval* precolored_fpu_intervals, *not_precolored_fpu_intervals;
create_unhandled_lists(&precolored_cpu_intervals, ¬_precolored_cpu_intervals, is_precolored_cpu_interval, is_virtual_cpu_interval);
if (has_fpu_registers()) {
create_unhandled_lists(&precolored_fpu_intervals, ¬_precolored_fpu_intervals, is_precolored_fpu_interval, is_virtual_fpu_interval);
#ifdef ASSERT
} else {
// fpu register allocation is omitted because no virtual fpu registers are present
// just check this again...
create_unhandled_lists(&precolored_fpu_intervals, ¬_precolored_fpu_intervals, is_precolored_fpu_interval, is_virtual_fpu_interval);
assert(not_precolored_fpu_intervals == Interval::end(), "missed an uncolored fpu interval");
#endif
}
// allocate cpu registers
LinearScanWalker cpu_lsw(this, precolored_cpu_intervals, not_precolored_cpu_intervals);
cpu_lsw.walk();
cpu_lsw.finish_allocation();
if (has_fpu_registers()) {
// allocate fpu registers
LinearScanWalker fpu_lsw(this, precolored_fpu_intervals, not_precolored_fpu_intervals);
fpu_lsw.walk();
fpu_lsw.finish_allocation();
}
}
// ********** Phase 6: resolve data flow
// (insert moves at edges between blocks if intervals have been split)
// wrapper for Interval::split_child_at_op_id that performs a bailout in product mode
// instead of returning NULL
Interval* LinearScan::split_child_at_op_id(Interval* interval, int op_id, LIR_OpVisitState::OprMode mode) {
Interval* result = interval->split_child_at_op_id(op_id, mode);
if (result != NULL) {
return result;
}
assert(false, "must find an interval, but do a clean bailout in product mode");
result = new Interval(LIR_OprDesc::vreg_base);
result->assign_reg(0);
result->set_type(T_INT);
BAILOUT_("LinearScan: interval is NULL", result);
}
Interval* LinearScan::interval_at_block_begin(BlockBegin* block, int reg_num) {
assert(LinearScan::nof_regs <= reg_num && reg_num < num_virtual_regs(), "register number out of bounds");
assert(interval_at(reg_num) != NULL, "no interval found");
return split_child_at_op_id(interval_at(reg_num), block->first_lir_instruction_id(), LIR_OpVisitState::outputMode);
}
Interval* LinearScan::interval_at_block_end(BlockBegin* block, int reg_num) {
assert(LinearScan::nof_regs <= reg_num && reg_num < num_virtual_regs(), "register number out of bounds");
assert(interval_at(reg_num) != NULL, "no interval found");
return split_child_at_op_id(interval_at(reg_num), block->last_lir_instruction_id() + 1, LIR_OpVisitState::outputMode);
}
Interval* LinearScan::interval_at_op_id(int reg_num, int op_id) {
assert(LinearScan::nof_regs <= reg_num && reg_num < num_virtual_regs(), "register number out of bounds");
assert(interval_at(reg_num) != NULL, "no interval found");
return split_child_at_op_id(interval_at(reg_num), op_id, LIR_OpVisitState::inputMode);
}
void LinearScan::resolve_collect_mappings(BlockBegin* from_block, BlockBegin* to_block, MoveResolver &move_resolver) {
DEBUG_ONLY(move_resolver.check_empty());
const int num_regs = num_virtual_regs();
const int size = live_set_size();
const BitMap live_at_edge = to_block->live_in();
// visit all registers where the live_at_edge bit is set
for (int r = (int)live_at_edge.get_next_one_offset(0, size); r < size; r = (int)live_at_edge.get_next_one_offset(r + 1, size)) {
assert(r < num_regs, "live information set for not exisiting interval");
assert(from_block->live_out().at(r) && to_block->live_in().at(r), "interval not live at this edge");
Interval* from_interval = interval_at_block_end(from_block, r);
Interval* to_interval = interval_at_block_begin(to_block, r);
if (from_interval != to_interval && (from_interval->assigned_reg() != to_interval->assigned_reg() || from_interval->assigned_regHi() != to_interval->assigned_regHi())) {
// need to insert move instruction
move_resolver.add_mapping(from_interval, to_interval);
}
}
}
void LinearScan::resolve_find_insert_pos(BlockBegin* from_block, BlockBegin* to_block, MoveResolver &move_resolver) {
if (from_block->number_of_sux() <= 1) {
TRACE_LINEAR_SCAN(4, tty->print_cr("inserting moves at end of from_block B%d", from_block->block_id()));
LIR_OpList* instructions = from_block->lir()->instructions_list();
LIR_OpBranch* branch = instructions->last()->as_OpBranch();
if (branch != NULL) {
// insert moves before branch
assert(branch->cond() == lir_cond_always, "block does not end with an unconditional jump");
move_resolver.set_insert_position(from_block->lir(), instructions->length() - 2);
} else {
move_resolver.set_insert_position(from_block->lir(), instructions->length() - 1);
}
} else {
TRACE_LINEAR_SCAN(4, tty->print_cr("inserting moves at beginning of to_block B%d", to_block->block_id()));
#ifdef ASSERT
assert(from_block->lir()->instructions_list()->at(0)->as_OpLabel() != NULL, "block does not start with a label");
// because the number of predecessor edges matches the number of
// successor edges, blocks which are reached by switch statements
// may have be more than one predecessor but it will be guaranteed
// that all predecessors will be the same.
for (int i = 0; i < to_block->number_of_preds(); i++) {
assert(from_block == to_block->pred_at(i), "all critical edges must be broken");
}
#endif
move_resolver.set_insert_position(to_block->lir(), 0);
}
}
// insert necessary moves (spilling or reloading) at edges between blocks if interval has been split
void LinearScan::resolve_data_flow() {
TIME_LINEAR_SCAN(timer_resolve_data_flow);
int num_blocks = block_count();
MoveResolver move_resolver(this);
BitMap block_completed(num_blocks); block_completed.clear();
BitMap already_resolved(num_blocks); already_resolved.clear();
int i;
for (i = 0; i < num_blocks; i++) {
BlockBegin* block = block_at(i);
// check if block has only one predecessor and only one successor
if (block->number_of_preds() == 1 && block->number_of_sux() == 1 && block->number_of_exception_handlers() == 0) {
LIR_OpList* instructions = block->lir()->instructions_list();
assert(instructions->at(0)->code() == lir_label, "block must start with label");
assert(instructions->last()->code() == lir_branch, "block with successors must end with branch");
assert(instructions->last()->as_OpBranch()->cond() == lir_cond_always, "block with successor must end with unconditional branch");
// check if block is empty (only label and branch)
if (instructions->length() == 2) {
BlockBegin* pred = block->pred_at(0);
BlockBegin* sux = block->sux_at(0);
// prevent optimization of two consecutive blocks
if (!block_completed.at(pred->linear_scan_number()) && !block_completed.at(sux->linear_scan_number())) {
TRACE_LINEAR_SCAN(3, tty->print_cr("**** optimizing empty block B%d (pred: B%d, sux: B%d)", block->block_id(), pred->block_id(), sux->block_id()));
block_completed.set_bit(block->linear_scan_number());
// directly resolve between pred and sux (without looking at the empty block between)
resolve_collect_mappings(pred, sux, move_resolver);
if (move_resolver.has_mappings()) {
move_resolver.set_insert_position(block->lir(), 0);
move_resolver.resolve_and_append_moves();
}
}
}
}
}
for (i = 0; i < num_blocks; i++) {
if (!block_completed.at(i)) {
BlockBegin* from_block = block_at(i);
already_resolved.set_from(block_completed);
int num_sux = from_block->number_of_sux();
for (int s = 0; s < num_sux; s++) {
BlockBegin* to_block = from_block->sux_at(s);
// check for duplicate edges between the same blocks (can happen with switch blocks)
if (!already_resolved.at(to_block->linear_scan_number())) {
TRACE_LINEAR_SCAN(3, tty->print_cr("**** processing edge between B%d and B%d", from_block->block_id(), to_block->block_id()));
already_resolved.set_bit(to_block->linear_scan_number());
// collect all intervals that have been split between from_block and to_block
resolve_collect_mappings(from_block, to_block, move_resolver);
if (move_resolver.has_mappings()) {
resolve_find_insert_pos(from_block, to_block, move_resolver);
move_resolver.resolve_and_append_moves();
}
}
}
}
}
}
void LinearScan::resolve_exception_entry(BlockBegin* block, int reg_num, MoveResolver &move_resolver) {
if (interval_at(reg_num) == NULL) {
// if a phi function is never used, no interval is created -> ignore this
return;
}
Interval* interval = interval_at_block_begin(block, reg_num);
int reg = interval->assigned_reg();
int regHi = interval->assigned_regHi();
if ((reg < nof_regs && interval->always_in_memory()) ||
(use_fpu_stack_allocation() && reg >= pd_first_fpu_reg && reg <= pd_last_fpu_reg)) {
// the interval is split to get a short range that is located on the stack
// in the following two cases:
// * the interval started in memory (e.g. method parameter), but is currently in a register
// this is an optimization for exception handling that reduces the number of moves that
// are necessary for resolving the states when an exception uses this exception handler
// * the interval would be on the fpu stack at the begin of the exception handler
// this is not allowed because of the complicated fpu stack handling on Intel
// range that will be spilled to memory
int from_op_id = block->first_lir_instruction_id();
int to_op_id = from_op_id + 1; // short live range of length 1
assert(interval->from() <= from_op_id && interval->to() >= to_op_id,
"no split allowed between exception entry and first instruction");
if (interval->from() != from_op_id) {
// the part before from_op_id is unchanged
interval = interval->split(from_op_id);
interval->assign_reg(reg, regHi);
append_interval(interval);
} else {
_needs_full_resort = true;
}
assert(interval->from() == from_op_id, "must be true now");
Interval* spilled_part = interval;
if (interval->to() != to_op_id) {
// the part after to_op_id is unchanged
spilled_part = interval->split_from_start(to_op_id);
append_interval(spilled_part);
move_resolver.add_mapping(spilled_part, interval);
}
assign_spill_slot(spilled_part);
assert(spilled_part->from() == from_op_id && spilled_part->to() == to_op_id, "just checking");
}
}
void LinearScan::resolve_exception_entry(BlockBegin* block, MoveResolver &move_resolver) {
assert(block->is_set(BlockBegin::exception_entry_flag), "should not call otherwise");
DEBUG_ONLY(move_resolver.check_empty());
// visit all registers where the live_in bit is set
int size = live_set_size();
for (int r = (int)block->live_in().get_next_one_offset(0, size); r < size; r = (int)block->live_in().get_next_one_offset(r + 1, size)) {
resolve_exception_entry(block, r, move_resolver);
}
// the live_in bits are not set for phi functions of the xhandler entry, so iterate them separately
for_each_phi_fun(block, phi,
resolve_exception_entry(block, phi->operand()->vreg_number(), move_resolver)
);
if (move_resolver.has_mappings()) {
// insert moves after first instruction
move_resolver.set_insert_position(block->lir(), 0);
move_resolver.resolve_and_append_moves();
}
}
void LinearScan::resolve_exception_edge(XHandler* handler, int throwing_op_id, int reg_num, Phi* phi, MoveResolver &move_resolver) {
if (interval_at(reg_num) == NULL) {
// if a phi function is never used, no interval is created -> ignore this
return;
}
// the computation of to_interval is equal to resolve_collect_mappings,
// but from_interval is more complicated because of phi functions
BlockBegin* to_block = handler->entry_block();
Interval* to_interval = interval_at_block_begin(to_block, reg_num);
if (phi != NULL) {
// phi function of the exception entry block
// no moves are created for this phi function in the LIR_Generator, so the
// interval at the throwing instruction must be searched using the operands
// of the phi function
Value from_value = phi->operand_at(handler->phi_operand());
// with phi functions it can happen that the same from_value is used in
// multiple mappings, so notify move-resolver that this is allowed
move_resolver.set_multiple_reads_allowed();
Constant* con = from_value->as_Constant();
if (con != NULL && !con->is_pinned()) {
// unpinned constants may have no register, so add mapping from constant to interval
move_resolver.add_mapping(LIR_OprFact::value_type(con->type()), to_interval);
} else {
// search split child at the throwing op_id
Interval* from_interval = interval_at_op_id(from_value->operand()->vreg_number(), throwing_op_id);
move_resolver.add_mapping(from_interval, to_interval);
}
} else {
// no phi function, so use reg_num also for from_interval
// search split child at the throwing op_id
Interval* from_interval = interval_at_op_id(reg_num, throwing_op_id);
if (from_interval != to_interval) {
// optimization to reduce number of moves: when to_interval is on stack and
// the stack slot is known to be always correct, then no move is necessary
if (!from_interval->always_in_memory() || from_interval->canonical_spill_slot() != to_interval->assigned_reg()) {
move_resolver.add_mapping(from_interval, to_interval);
}
}
}
}
void LinearScan::resolve_exception_edge(XHandler* handler, int throwing_op_id, MoveResolver &move_resolver) {
TRACE_LINEAR_SCAN(4, tty->print_cr("resolving exception handler B%d: throwing_op_id=%d", handler->entry_block()->block_id(), throwing_op_id));
DEBUG_ONLY(move_resolver.check_empty());
assert(handler->lir_op_id() == -1, "already processed this xhandler");
DEBUG_ONLY(handler->set_lir_op_id(throwing_op_id));
assert(handler->entry_code() == NULL, "code already present");
// visit all registers where the live_in bit is set
BlockBegin* block = handler->entry_block();
int size = live_set_size();
for (int r = (int)block->live_in().get_next_one_offset(0, size); r < size; r = (int)block->live_in().get_next_one_offset(r + 1, size)) {
resolve_exception_edge(handler, throwing_op_id, r, NULL, move_resolver);
}
// the live_in bits are not set for phi functions of the xhandler entry, so iterate them separately
for_each_phi_fun(block, phi,
resolve_exception_edge(handler, throwing_op_id, phi->operand()->vreg_number(), phi, move_resolver)
);
if (move_resolver.has_mappings()) {
LIR_List* entry_code = new LIR_List(compilation());
move_resolver.set_insert_position(entry_code, 0);
move_resolver.resolve_and_append_moves();
entry_code->jump(handler->entry_block());
handler->set_entry_code(entry_code);
}
}
void LinearScan::resolve_exception_handlers() {
MoveResolver move_resolver(this);
LIR_OpVisitState visitor;
int num_blocks = block_count();
int i;
for (i = 0; i < num_blocks; i++) {
BlockBegin* block = block_at(i);
if (block->is_set(BlockBegin::exception_entry_flag)) {
resolve_exception_entry(block, move_resolver);
}
}
for (i = 0; i < num_blocks; i++) {
BlockBegin* block = block_at(i);
LIR_List* ops = block->lir();
int num_ops = ops->length();
// iterate all instructions of the block. skip the first because it is always a label
assert(visitor.no_operands(ops->at(0)), "first operation must always be a label");
for (int j = 1; j < num_ops; j++) {
LIR_Op* op = ops->at(j);
int op_id = op->id();
if (op_id != -1 && has_info(op_id)) {
// visit operation to collect all operands
visitor.visit(op);
assert(visitor.info_count() > 0, "should not visit otherwise");
XHandlers* xhandlers = visitor.all_xhandler();
int n = xhandlers->length();
for (int k = 0; k < n; k++) {
resolve_exception_edge(xhandlers->handler_at(k), op_id, move_resolver);
}
#ifdef ASSERT
} else {
visitor.visit(op);
assert(visitor.all_xhandler()->length() == 0, "missed exception handler");
#endif
}
}
}
}
// ********** Phase 7: assign register numbers back to LIR
// (includes computation of debug information and oop maps)
VMReg LinearScan::vm_reg_for_interval(Interval* interval) {
VMReg reg = interval->cached_vm_reg();
if (!reg->is_valid() ) {
reg = vm_reg_for_operand(operand_for_interval(interval));
interval->set_cached_vm_reg(reg);
}
assert(reg == vm_reg_for_operand(operand_for_interval(interval)), "wrong cached value");
return reg;
}
VMReg LinearScan::vm_reg_for_operand(LIR_Opr opr) {
assert(opr->is_oop(), "currently only implemented for oop operands");
return frame_map()->regname(opr);
}
LIR_Opr LinearScan::operand_for_interval(Interval* interval) {
LIR_Opr opr = interval->cached_opr();
if (opr->is_illegal()) {
opr = calc_operand_for_interval(interval);
interval->set_cached_opr(opr);
}
assert(opr == calc_operand_for_interval(interval), "wrong cached value");
return opr;
}
LIR_Opr LinearScan::calc_operand_for_interval(const Interval* interval) {
int assigned_reg = interval->assigned_reg();
BasicType type = interval->type();
if (assigned_reg >= nof_regs) {
// stack slot
assert(interval->assigned_regHi() == any_reg, "must not have hi register");
return LIR_OprFact::stack(assigned_reg - nof_regs, type);
} else {
// register
switch (type) {
case T_OBJECT: {
assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
assert(interval->assigned_regHi() == any_reg, "must not have hi register");
return LIR_OprFact::single_cpu_oop(assigned_reg);
}
case T_ADDRESS: {
assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
assert(interval->assigned_regHi() == any_reg, "must not have hi register");
return LIR_OprFact::single_cpu_address(assigned_reg);
}
case T_METADATA: {
assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
assert(interval->assigned_regHi() == any_reg, "must not have hi register");
return LIR_OprFact::single_cpu_metadata(assigned_reg);
}
#ifdef __SOFTFP__
case T_FLOAT: // fall through
#endif // __SOFTFP__
case T_INT: {
assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
assert(interval->assigned_regHi() == any_reg, "must not have hi register");
return LIR_OprFact::single_cpu(assigned_reg);
}
#ifdef __SOFTFP__
case T_DOUBLE: // fall through
#endif // __SOFTFP__
case T_LONG: {
int assigned_regHi = interval->assigned_regHi();
assert(assigned_reg >= pd_first_cpu_reg && assigned_reg <= pd_last_cpu_reg, "no cpu register");
assert(num_physical_regs(T_LONG) == 1 ||
(assigned_regHi >= pd_first_cpu_reg && assigned_regHi <= pd_last_cpu_reg), "no cpu register");
assert(assigned_reg != assigned_regHi, "invalid allocation");
assert(num_physical_regs(T_LONG) == 1 || assigned_reg < assigned_regHi,
"register numbers must be sorted (ensure that e.g. a move from eax,ebx to ebx,eax can not occur)");
assert((assigned_regHi != any_reg) ^ (num_physical_regs(T_LONG) == 1), "must be match");
if (requires_adjacent_regs(T_LONG)) {
assert(assigned_reg % 2 == 0 && assigned_reg + 1 == assigned_regHi, "must be sequential and even");
}
#ifdef _LP64
return LIR_OprFact::double_cpu(assigned_reg, assigned_reg);
#else
#if defined(SPARC) || defined(PPC)
return LIR_OprFact::double_cpu(assigned_regHi, assigned_reg);
#else
return LIR_OprFact::double_cpu(assigned_reg, assigned_regHi);
#endif // SPARC
#endif // LP64
}
#ifndef __SOFTFP__
case T_FLOAT: {
#ifdef X86
if (UseSSE >= 1) {
assert(assigned_reg >= pd_first_xmm_reg && assigned_reg <= pd_last_xmm_reg, "no xmm register");
assert(interval->assigned_regHi() == any_reg, "must not have hi register");
return LIR_OprFact::single_xmm(assigned_reg - pd_first_xmm_reg);
}
#endif
assert(assigned_reg >= pd_first_fpu_reg && assigned_reg <= pd_last_fpu_reg, "no fpu register");
assert(interval->assigned_regHi() == any_reg, "must not have hi register");
return LIR_OprFact::single_fpu(assigned_reg - pd_first_fpu_reg);
}
case T_DOUBLE: {
#ifdef X86
if (UseSSE >= 2) {
assert(assigned_reg >= pd_first_xmm_reg && assigned_reg <= pd_last_xmm_reg, "no xmm register");
assert(interval->assigned_regHi() == any_reg, "must not have hi register (double xmm values are stored in one register)");
return LIR_OprFact::double_xmm(assigned_reg - pd_first_xmm_reg);
}
#endif
#ifdef SPARC
assert(assigned_reg >= pd_first_fpu_reg && assigned_reg <= pd_last_fpu_reg, "no fpu register");
assert(interval->assigned_regHi() >= pd_first_fpu_reg && interval->assigned_regHi() <= pd_last_fpu_reg, "no fpu register");
assert(assigned_reg % 2 == 0 && assigned_reg + 1 == interval->assigned_regHi(), "must be sequential and even");
LIR_Opr result = LIR_OprFact::double_fpu(interval->assigned_regHi() - pd_first_fpu_reg, assigned_reg - pd_first_fpu_reg);
#elif defined(ARM)
assert(assigned_reg >= pd_first_fpu_reg && assigned_reg <= pd_last_fpu_reg, "no fpu register");
assert(interval->assigned_regHi() >= pd_first_fpu_reg && interval->assigned_regHi() <= pd_last_fpu_reg, "no fpu register");
assert(assigned_reg % 2 == 0 && assigned_reg + 1 == interval->assigned_regHi(), "must be sequential and even");
LIR_Opr result = LIR_OprFact::double_fpu(assigned_reg - pd_first_fpu_reg, interval->assigned_regHi() - pd_first_fpu_reg);
#else
assert(assigned_reg >= pd_first_fpu_reg && assigned_reg <= pd_last_fpu_reg, "no fpu register");
assert(interval->assigned_regHi() == any_reg, "must not have hi register (double fpu values are stored in one register on Intel)");
LIR_Opr result = LIR_OprFact::double_fpu(assigned_reg - pd_first_fpu_reg);
#endif
return result;
}
#endif // __SOFTFP__
default: {
ShouldNotReachHere();
return LIR_OprFact::illegalOpr;
}
}
}
}
LIR_Opr LinearScan::canonical_spill_opr(Interval* interval) {
assert(interval->canonical_spill_slot() >= nof_regs, "canonical spill slot not set");
return LIR_OprFact::stack(interval->canonical_spill_slot() - nof_regs, interval->type());
}
LIR_Opr LinearScan::color_lir_opr(LIR_Opr opr, int op_id, LIR_OpVisitState::OprMode mode) {
assert(opr->is_virtual(), "should not call this otherwise");
Interval* interval = interval_at(opr->vreg_number());
assert(interval != NULL, "interval must exist");
if (op_id != -1) {
#ifdef ASSERT
BlockBegin* block = block_of_op_with_id(op_id);
if (block->number_of_sux() <= 1 && op_id == block->last_lir_instruction_id()) {
// check if spill moves could have been appended at the end of this block, but
// before the branch instruction. So the split child information for this branch would
// be incorrect.
LIR_OpBranch* branch = block->lir()->instructions_list()->last()->as_OpBranch();
if (branch != NULL) {
if (block->live_out().at(opr->vreg_number())) {
assert(branch->cond() == lir_cond_always, "block does not end with an unconditional jump");
assert(false, "can't get split child for the last branch of a block because the information would be incorrect (moves are inserted before the branch in resolve_data_flow)");
}
}
}
#endif
// operands are not changed when an interval is split during allocation,
// so search the right interval here
interval = split_child_at_op_id(interval, op_id, mode);
}
LIR_Opr res = operand_for_interval(interval);
#ifdef X86
// new semantic for is_last_use: not only set on definite end of interval,
// but also before hole
// This may still miss some cases (e.g. for dead values), but it is not necessary that the
// last use information is completely correct
// information is only needed for fpu stack allocation
if (res->is_fpu_register()) {
if (opr->is_last_use() || op_id == interval->to() || (op_id != -1 && interval->has_hole_between(op_id, op_id + 1))) {
assert(op_id == -1 || !is_block_begin(op_id), "holes at begin of block may also result from control flow");
res = res->make_last_use();
}
}
#endif
assert(!gen()->is_vreg_flag_set(opr->vreg_number(), LIRGenerator::callee_saved) || !FrameMap::is_caller_save_register(res), "bad allocation");
return res;
}
#ifdef ASSERT
// some methods used to check correctness of debug information
void assert_no_register_values(GrowableArray<ScopeValue*>* values) {
if (values == NULL) {
return;
}
for (int i = 0; i < values->length(); i++) {
ScopeValue* value = values->at(i);
if (value->is_location()) {
Location location = ((LocationValue*)value)->location();
assert(location.where() == Location::on_stack, "value is in register");
}
}
}
void assert_no_register_values(GrowableArray<MonitorValue*>* values) {
if (values == NULL) {
return;
}
for (int i = 0; i < values->length(); i++) {
MonitorValue* value = values->at(i);
if (value->owner()->is_location()) {
Location location = ((LocationValue*)value->owner())->location();
assert(location.where() == Location::on_stack, "owner is in register");
}
assert(value->basic_lock().where() == Location::on_stack, "basic_lock is in register");
}
}
void assert_equal(Location l1, Location l2) {
assert(l1.where() == l2.where() && l1.type() == l2.type() && l1.offset() == l2.offset(), "");
}
void assert_equal(ScopeValue* v1, ScopeValue* v2) {
if (v1->is_location()) {
assert(v2->is_location(), "");
assert_equal(((LocationValue*)v1)->location(), ((LocationValue*)v2)->location());
} else if (v1->is_constant_int()) {
assert(v2->is_constant_int(), "");
assert(((ConstantIntValue*)v1)->value() == ((ConstantIntValue*)v2)->value(), "");
} else if (v1->is_constant_double()) {
assert(v2->is_constant_double(), "");
assert(((ConstantDoubleValue*)v1)->value() == ((ConstantDoubleValue*)v2)->value(), "");
} else if (v1->is_constant_long()) {
assert(v2->is_constant_long(), "");
assert(((ConstantLongValue*)v1)->value() == ((ConstantLongValue*)v2)->value(), "");
} else if (v1->is_constant_oop()) {
assert(v2->is_constant_oop(), "");
assert(((ConstantOopWriteValue*)v1)->value() == ((ConstantOopWriteValue*)v2)->value(), "");
} else {
ShouldNotReachHere();
}
}
void assert_equal(MonitorValue* m1, MonitorValue* m2) {
assert_equal(m1->owner(), m2->owner());
assert_equal(m1->basic_lock(), m2->basic_lock());
}
void assert_equal(IRScopeDebugInfo* d1, IRScopeDebugInfo* d2) {
assert(d1->scope() == d2->scope(), "not equal");
assert(d1->bci() == d2->bci(), "not equal");
if (d1->locals() != NULL) {
assert(d1->locals() != NULL && d2->locals() != NULL, "not equal");
assert(d1->locals()->length() == d2->locals()->length(), "not equal");
for (int i = 0; i < d1->locals()->length(); i++) {
assert_equal(d1->locals()->at(i), d2->locals()->at(i));
}
} else {
assert(d1->locals() == NULL && d2->locals() == NULL, "not equal");
}
if (d1->expressions() != NULL) {
assert(d1->expressions() != NULL && d2->expressions() != NULL, "not equal");
assert(d1->expressions()->length() == d2->expressions()->length(), "not equal");
for (int i = 0; i < d1->expressions()->length(); i++) {
assert_equal(d1->expressions()->at(i), d2->expressions()->at(i));
}
} else {
assert(d1->expressions() == NULL && d2->expressions() == NULL, "not equal");
}
if (d1->monitors() != NULL) {
assert(d1->monitors() != NULL && d2->monitors() != NULL, "not equal");
assert(d1->monitors()->length() == d2->monitors()->length(), "not equal");
for (int i = 0; i < d1->monitors()->length(); i++) {
assert_equal(d1->monitors()->at(i), d2->monitors()->at(i));
}
} else {
assert(d1->monitors() == NULL && d2->monitors() == NULL, "not equal");
}
if (d1->caller() != NULL) {
assert(d1->caller() != NULL && d2->caller() != NULL, "not equal");
assert_equal(d1->caller(), d2->caller());
} else {
assert(d1->caller() == NULL && d2->caller() == NULL, "not equal");
}
}
void check_stack_depth(CodeEmitInfo* info, int stack_end) {
if (info->stack()->bci() != SynchronizationEntryBCI && !info->scope()->method()->is_native()) {
Bytecodes::Code code = info->scope()->method()->java_code_at_bci(info->stack()->bci());
switch (code) {
case Bytecodes::_ifnull : // fall through
case Bytecodes::_ifnonnull : // fall through
case Bytecodes::_ifeq : // fall through
case Bytecodes::_ifne : // fall through
case Bytecodes::_iflt : // fall through
case Bytecodes::_ifge : // fall through
case Bytecodes::_ifgt : // fall through
case Bytecodes::_ifle : // fall through
case Bytecodes::_if_icmpeq : // fall through
case Bytecodes::_if_icmpne : // fall through
case Bytecodes::_if_icmplt : // fall through
case Bytecodes::_if_icmpge : // fall through
case Bytecodes::_if_icmpgt : // fall through
case Bytecodes::_if_icmple : // fall through
case Bytecodes::_if_acmpeq : // fall through
case Bytecodes::_if_acmpne :
assert(stack_end >= -Bytecodes::depth(code), "must have non-empty expression stack at if bytecode");
break;
}
}
}
#endif // ASSERT
IntervalWalker* LinearScan::init_compute_oop_maps() {
// setup lists of potential oops for walking
Interval* oop_intervals;
Interval* non_oop_intervals;
create_unhandled_lists(&oop_intervals, &non_oop_intervals, is_oop_interval, NULL);
// intervals that have no oops inside need not to be processed
// to ensure a walking until the last instruction id, add a dummy interval
// with a high operation id
non_oop_intervals = new Interval(any_reg);
non_oop_intervals->add_range(max_jint - 2, max_jint - 1);
return new IntervalWalker(this, oop_intervals, non_oop_intervals);
}
OopMap* LinearScan::compute_oop_map(IntervalWalker* iw, LIR_Op* op, CodeEmitInfo* info, bool is_call_site) {
TRACE_LINEAR_SCAN(3, tty->print_cr("creating oop map at op_id %d", op->id()));
// walk before the current operation -> intervals that start at
// the operation (= output operands of the operation) are not
// included in the oop map
iw->walk_before(op->id());
int frame_size = frame_map()->framesize();
int arg_count = frame_map()->oop_map_arg_count();
OopMap* map = new OopMap(frame_size, arg_count);
// Check if this is a patch site.
bool is_patch_info = false;
if (op->code() == lir_move) {
assert(!is_call_site, "move must not be a call site");
assert(op->as_Op1() != NULL, "move must be LIR_Op1");
LIR_Op1* move = (LIR_Op1*)op;
is_patch_info = move->patch_code() != lir_patch_none;
}
// Iterate through active intervals
for (Interval* interval = iw->active_first(fixedKind); interval != Interval::end(); interval = interval->next()) {
int assigned_reg = interval->assigned_reg();
assert(interval->current_from() <= op->id() && op->id() <= interval->current_to(), "interval should not be active otherwise");
assert(interval->assigned_regHi() == any_reg, "oop must be single word");
assert(interval->reg_num() >= LIR_OprDesc::vreg_base, "fixed interval found");
// Check if this range covers the instruction. Intervals that
// start or end at the current operation are not included in the
// oop map, except in the case of patching moves. For patching
// moves, any intervals which end at this instruction are included
// in the oop map since we may safepoint while doing the patch
// before we've consumed the inputs.
if (is_patch_info || op->id() < interval->current_to()) {
// caller-save registers must not be included into oop-maps at calls
assert(!is_call_site || assigned_reg >= nof_regs || !is_caller_save(assigned_reg), "interval is in a caller-save register at a call -> register will be overwritten");
VMReg name = vm_reg_for_interval(interval);
set_oop(map, name);
// Spill optimization: when the stack value is guaranteed to be always correct,
// then it must be added to the oop map even if the interval is currently in a register
if (interval->always_in_memory() &&
op->id() > interval->spill_definition_pos() &&
interval->assigned_reg() != interval->canonical_spill_slot()) {
assert(interval->spill_definition_pos() > 0, "position not set correctly");
assert(interval->canonical_spill_slot() >= LinearScan::nof_regs, "no spill slot assigned");
assert(interval->assigned_reg() < LinearScan::nof_regs, "interval is on stack, so stack slot is registered twice");
set_oop(map, frame_map()->slot_regname(interval->canonical_spill_slot() - LinearScan::nof_regs));
}
}
}
// add oops from lock stack
assert(info->stack() != NULL, "CodeEmitInfo must always have a stack");
int locks_count = info->stack()->total_locks_size();
for (int i = 0; i < locks_count; i++) {
set_oop(map, frame_map()->monitor_object_regname(i));
}
return map;
}
void LinearScan::compute_oop_map(IntervalWalker* iw, const LIR_OpVisitState &visitor, LIR_Op* op) {
assert(visitor.info_count() > 0, "no oop map needed");
// compute oop_map only for first CodeEmitInfo
// because it is (in most cases) equal for all other infos of the same operation
CodeEmitInfo* first_info = visitor.info_at(0);
OopMap* first_oop_map = compute_oop_map(iw, op, first_info, visitor.has_call());
for (int i = 0; i < visitor.info_count(); i++) {
CodeEmitInfo* info = visitor.info_at(i);
OopMap* oop_map = first_oop_map;
if (info->stack()->locks_size() != first_info->stack()->locks_size()) {
// this info has a different number of locks then the precomputed oop map
// (possible for lock and unlock instructions) -> compute oop map with
// correct lock information
oop_map = compute_oop_map(iw, op, info, visitor.has_call());
}
if (info->_oop_map == NULL) {
info->_oop_map = oop_map;
} else {
// a CodeEmitInfo can not be shared between different LIR-instructions
// because interval splitting can occur anywhere between two instructions
// and so the oop maps must be different
// -> check if the already set oop_map is exactly the one calculated for this operation
assert(info->_oop_map == oop_map, "same CodeEmitInfo used for multiple LIR instructions");
}
}
}
// frequently used constants
// Allocate them with new so they are never destroyed (otherwise, a
// forced exit could destroy these objects while they are still in
// use).
ConstantOopWriteValue* LinearScan::_oop_null_scope_value = new (ResourceObj::C_HEAP, mtCompiler) ConstantOopWriteValue(NULL);
ConstantIntValue* LinearScan::_int_m1_scope_value = new (ResourceObj::C_HEAP, mtCompiler) ConstantIntValue(-1);
ConstantIntValue* LinearScan::_int_0_scope_value = new (ResourceObj::C_HEAP, mtCompiler) ConstantIntValue(0);
ConstantIntValue* LinearScan::_int_1_scope_value = new (ResourceObj::C_HEAP, mtCompiler) ConstantIntValue(1);
ConstantIntValue* LinearScan::_int_2_scope_value = new (ResourceObj::C_HEAP, mtCompiler) ConstantIntValue(2);
LocationValue* _illegal_value = new (ResourceObj::C_HEAP, mtCompiler) LocationValue(Location());
void LinearScan::init_compute_debug_info() {
// cache for frequently used scope values
// (cpu registers and stack slots)
_scope_value_cache = ScopeValueArray((LinearScan::nof_cpu_regs + frame_map()->argcount() + max_spills()) * 2, NULL);
}
MonitorValue* LinearScan::location_for_monitor_index(int monitor_index) {
Location loc;
if (!frame_map()->location_for_monitor_object(monitor_index, &loc)) {
bailout("too large frame");
}
ScopeValue* object_scope_value = new LocationValue(loc);
if (!frame_map()->location_for_monitor_lock(monitor_index, &loc)) {
bailout("too large frame");
}
return new MonitorValue(object_scope_value, loc);
}
LocationValue* LinearScan::location_for_name(int name, Location::Type loc_type) {
Location loc;
if (!frame_map()->locations_for_slot(name, loc_type, &loc)) {
bailout("too large frame");
}
return new LocationValue(loc);
}
int LinearScan::append_scope_value_for_constant(LIR_Opr opr, GrowableArray<ScopeValue*>* scope_values) {
assert(opr->is_constant(), "should not be called otherwise");
LIR_Const* c = opr->as_constant_ptr();
BasicType t = c->type();
switch (t) {
case T_OBJECT: {
jobject value = c->as_jobject();
if (value == NULL) {
scope_values->append(_oop_null_scope_value);
} else {
scope_values->append(new ConstantOopWriteValue(c->as_jobject()));
}
return 1;
}
case T_INT: // fall through
case T_FLOAT: {
int value = c->as_jint_bits();
switch (value) {
case -1: scope_values->append(_int_m1_scope_value); break;
case 0: scope_values->append(_int_0_scope_value); break;
case 1: scope_values->append(_int_1_scope_value); break;
case 2: scope_values->append(_int_2_scope_value); break;
default: scope_values->append(new ConstantIntValue(c->as_jint_bits())); break;
}
return 1;
}
case T_LONG: // fall through
case T_DOUBLE: {
#ifdef _LP64
scope_values->append(_int_0_scope_value);
scope_values->append(new ConstantLongValue(c->as_jlong_bits()));
#else
if (hi_word_offset_in_bytes > lo_word_offset_in_bytes) {
scope_values->append(new ConstantIntValue(c->as_jint_hi_bits()));
scope_values->append(new ConstantIntValue(c->as_jint_lo_bits()));
} else {
scope_values->append(new ConstantIntValue(c->as_jint_lo_bits()));
scope_values->append(new ConstantIntValue(c->as_jint_hi_bits()));
}
#endif
return 2;
}
case T_ADDRESS: {
#ifdef _LP64
scope_values->append(new ConstantLongValue(c->as_jint()));
#else
scope_values->append(new ConstantIntValue(c->as_jint()));
#endif
return 1;
}
default:
ShouldNotReachHere();
return -1;
}
}
int LinearScan::append_scope_value_for_operand(LIR_Opr opr, GrowableArray<ScopeValue*>* scope_values) {
if (opr->is_single_stack()) {
int stack_idx = opr->single_stack_ix();
bool is_oop = opr->is_oop_register();
int cache_idx = (stack_idx + LinearScan::nof_cpu_regs) * 2 + (is_oop ? 1 : 0);
ScopeValue* sv = _scope_value_cache.at(cache_idx);
if (sv == NULL) {
Location::Type loc_type = is_oop ? Location::oop : Location::normal;
sv = location_for_name(stack_idx, loc_type);
_scope_value_cache.at_put(cache_idx, sv);
}
// check if cached value is correct
DEBUG_ONLY(assert_equal(sv, location_for_name(stack_idx, is_oop ? Location::oop : Location::normal)));
scope_values->append(sv);
return 1;
} else if (opr->is_single_cpu()) {
bool is_oop = opr->is_oop_register();
int cache_idx = opr->cpu_regnr() * 2 + (is_oop ? 1 : 0);
Location::Type int_loc_type = NOT_LP64(Location::normal) LP64_ONLY(Location::int_in_long);
ScopeValue* sv = _scope_value_cache.at(cache_idx);
if (sv == NULL) {
Location::Type loc_type = is_oop ? Location::oop : int_loc_type;
VMReg rname = frame_map()->regname(opr);
sv = new LocationValue(Location::new_reg_loc(loc_type, rname));
_scope_value_cache.at_put(cache_idx, sv);
}
// check if cached value is correct
DEBUG_ONLY(assert_equal(sv, new LocationValue(Location::new_reg_loc(is_oop ? Location::oop : int_loc_type, frame_map()->regname(opr)))));
scope_values->append(sv);
return 1;
#ifdef X86
} else if (opr->is_single_xmm()) {
VMReg rname = opr->as_xmm_float_reg()->as_VMReg();
LocationValue* sv = new LocationValue(Location::new_reg_loc(Location::normal, rname));
scope_values->append(sv);
return 1;
#endif
} else if (opr->is_single_fpu()) {
#ifdef X86
// the exact location of fpu stack values is only known
// during fpu stack allocation, so the stack allocator object
// must be present
assert(use_fpu_stack_allocation(), "should not have float stack values without fpu stack allocation (all floats must be SSE2)");
assert(_fpu_stack_allocator != NULL, "must be present");
opr = _fpu_stack_allocator->to_fpu_stack(opr);
#endif
Location::Type loc_type = float_saved_as_double ? Location::float_in_dbl : Location::normal;
VMReg rname = frame_map()->fpu_regname(opr->fpu_regnr());
#ifndef __SOFTFP__
#ifndef VM_LITTLE_ENDIAN
if (! float_saved_as_double) {
// On big endian system, we may have an issue if float registers use only
// the low half of the (same) double registers.
// Both the float and the double could have the same regnr but would correspond
// to two different addresses once saved.
// get next safely (no assertion checks)
VMReg next = VMRegImpl::as_VMReg(1+rname->value());
if (next->is_reg() &&
(next->as_FloatRegister() == rname->as_FloatRegister())) {
// the back-end does use the same numbering for the double and the float
rname = next; // VMReg for the low bits, e.g. the real VMReg for the float
}
}
#endif
#endif
LocationValue* sv = new LocationValue(Location::new_reg_loc(loc_type, rname));
scope_values->append(sv);
return 1;
} else {
// double-size operands
ScopeValue* first;
ScopeValue* second;
if (opr->is_double_stack()) {
#ifdef _LP64
Location loc1;
Location::Type loc_type = opr->type() == T_LONG ? Location::lng : Location::dbl;
if (!frame_map()->locations_for_slot(opr->double_stack_ix(), loc_type, &loc1, NULL)) {
bailout("too large frame");
}
// Does this reverse on x86 vs. sparc?
first = new LocationValue(loc1);
second = _int_0_scope_value;
#else
Location loc1, loc2;
if (!frame_map()->locations_for_slot(opr->double_stack_ix(), Location::normal, &loc1, &loc2)) {
bailout("too large frame");
}
first = new LocationValue(loc1);
second = new LocationValue(loc2);
#endif // _LP64
} else if (opr->is_double_cpu()) {
#ifdef _LP64
VMReg rname_first = opr->as_register_lo()->as_VMReg();
first = new LocationValue(Location::new_reg_loc(Location::lng, rname_first));
second = _int_0_scope_value;
#else
VMReg rname_first = opr->as_register_lo()->as_VMReg();
VMReg rname_second = opr->as_register_hi()->as_VMReg();
if (hi_word_offset_in_bytes < lo_word_offset_in_bytes) {
// lo/hi and swapped relative to first and second, so swap them
VMReg tmp = rname_first;
rname_first = rname_second;
rname_second = tmp;
}
first = new LocationValue(Location::new_reg_loc(Location::normal, rname_first));
second = new LocationValue(Location::new_reg_loc(Location::normal, rname_second));
#endif //_LP64
#ifdef X86
} else if (opr->is_double_xmm()) {
assert(opr->fpu_regnrLo() == opr->fpu_regnrHi(), "assumed in calculation");
VMReg rname_first = opr->as_xmm_double_reg()->as_VMReg();
# ifdef _LP64
first = new LocationValue(Location::new_reg_loc(Location::dbl, rname_first));
second = _int_0_scope_value;
# else
first = new LocationValue(Location::new_reg_loc(Location::normal, rname_first));
// %%% This is probably a waste but we'll keep things as they were for now
if (true) {
VMReg rname_second = rname_first->next();
second = new LocationValue(Location::new_reg_loc(Location::normal, rname_second));
}
# endif
#endif
} else if (opr->is_double_fpu()) {
// On SPARC, fpu_regnrLo/fpu_regnrHi represents the two halves of
// the double as float registers in the native ordering. On X86,
// fpu_regnrLo is a FPU stack slot whose VMReg represents
// the low-order word of the double and fpu_regnrLo + 1 is the
// name for the other half. *first and *second must represent the
// least and most significant words, respectively.
#ifdef X86
// the exact location of fpu stack values is only known
// during fpu stack allocation, so the stack allocator object
// must be present
assert(use_fpu_stack_allocation(), "should not have float stack values without fpu stack allocation (all floats must be SSE2)");
assert(_fpu_stack_allocator != NULL, "must be present");
opr = _fpu_stack_allocator->to_fpu_stack(opr);
assert(opr->fpu_regnrLo() == opr->fpu_regnrHi(), "assumed in calculation (only fpu_regnrLo is used)");
#endif
#ifdef SPARC
assert(opr->fpu_regnrLo() == opr->fpu_regnrHi() + 1, "assumed in calculation (only fpu_regnrHi is used)");
#endif
#ifdef ARM
assert(opr->fpu_regnrHi() == opr->fpu_regnrLo() + 1, "assumed in calculation (only fpu_regnrLo is used)");
#endif
#ifdef PPC
assert(opr->fpu_regnrLo() == opr->fpu_regnrHi(), "assumed in calculation (only fpu_regnrHi is used)");
#endif
#ifdef VM_LITTLE_ENDIAN
VMReg rname_first = frame_map()->fpu_regname(opr->fpu_regnrLo());
#else
VMReg rname_first = frame_map()->fpu_regname(opr->fpu_regnrHi());
#endif
#ifdef _LP64
first = new LocationValue(Location::new_reg_loc(Location::dbl, rname_first));
second = _int_0_scope_value;
#else
first = new LocationValue(Location::new_reg_loc(Location::normal, rname_first));
// %%% This is probably a waste but we'll keep things as they were for now
if (true) {
VMReg rname_second = rname_first->next();
second = new LocationValue(Location::new_reg_loc(Location::normal, rname_second));
}
#endif
} else {
ShouldNotReachHere();
first = NULL;
second = NULL;
}
assert(first != NULL && second != NULL, "must be set");
// The convention the interpreter uses is that the second local
// holds the first raw word of the native double representation.
// This is actually reasonable, since locals and stack arrays
// grow downwards in all implementations.
// (If, on some machine, the interpreter's Java locals or stack
// were to grow upwards, the embedded doubles would be word-swapped.)
scope_values->append(second);
scope_values->append(first);
return 2;
}
}
int LinearScan::append_scope_value(int op_id, Value value, GrowableArray<ScopeValue*>* scope_values) {
if (value != NULL) {
LIR_Opr opr = value->operand();
Constant* con = value->as_Constant();
assert(con == NULL || opr->is_virtual() || opr->is_constant() || opr->is_illegal(), "asumption: Constant instructions have only constant operands (or illegal if constant is optimized away)");
assert(con != NULL || opr->is_virtual(), "asumption: non-Constant instructions have only virtual operands");
if (con != NULL && !con->is_pinned() && !opr->is_constant()) {
// Unpinned constants may have a virtual operand for a part of the lifetime
// or may be illegal when it was optimized away,
// so always use a constant operand
opr = LIR_OprFact::value_type(con->type());
}
assert(opr->is_virtual() || opr->is_constant(), "other cases not allowed here");
if (opr->is_virtual()) {
LIR_OpVisitState::OprMode mode = LIR_OpVisitState::inputMode;
BlockBegin* block = block_of_op_with_id(op_id);
if (block->number_of_sux() == 1 && op_id == block->last_lir_instruction_id()) {
// generating debug information for the last instruction of a block.
// if this instruction is a branch, spill moves are inserted before this branch
// and so the wrong operand would be returned (spill moves at block boundaries are not
// considered in the live ranges of intervals)
// Solution: use the first op_id of the branch target block instead.
if (block->lir()->instructions_list()->last()->as_OpBranch() != NULL) {
if (block->live_out().at(opr->vreg_number())) {
op_id = block->sux_at(0)->first_lir_instruction_id();
mode = LIR_OpVisitState::outputMode;
}
}
}
// Get current location of operand
// The operand must be live because debug information is considered when building the intervals
// if the interval is not live, color_lir_opr will cause an assertion failure
opr = color_lir_opr(opr, op_id, mode);
assert(!has_call(op_id) || opr->is_stack() || !is_caller_save(reg_num(opr)), "can not have caller-save register operands at calls");
// Append to ScopeValue array
return append_scope_value_for_operand(opr, scope_values);
} else {
assert(value->as_Constant() != NULL, "all other instructions have only virtual operands");
assert(opr->is_constant(), "operand must be constant");
return append_scope_value_for_constant(opr, scope_values);
}
} else {
// append a dummy value because real value not needed
scope_values->append(_illegal_value);
return 1;
}
}
IRScopeDebugInfo* LinearScan::compute_debug_info_for_scope(int op_id, IRScope* cur_scope, ValueStack* cur_state, ValueStack* innermost_state) {
IRScopeDebugInfo* caller_debug_info = NULL;
ValueStack* caller_state = cur_state->caller_state();
if (caller_state != NULL) {
// process recursively to compute outermost scope first
caller_debug_info = compute_debug_info_for_scope(op_id, cur_scope->caller(), caller_state, innermost_state);
}
// initialize these to null.
// If we don't need deopt info or there are no locals, expressions or monitors,
// then these get recorded as no information and avoids the allocation of 0 length arrays.
GrowableArray<ScopeValue*>* locals = NULL;
GrowableArray<ScopeValue*>* expressions = NULL;
GrowableArray<MonitorValue*>* monitors = NULL;
// describe local variable values
int nof_locals = cur_state->locals_size();
if (nof_locals > 0) {
locals = new GrowableArray<ScopeValue*>(nof_locals);
int pos = 0;
while (pos < nof_locals) {
assert(pos < cur_state->locals_size(), "why not?");
Value local = cur_state->local_at(pos);
pos += append_scope_value(op_id, local, locals);
assert(locals->length() == pos, "must match");
}
assert(locals->length() == cur_scope->method()->max_locals(), "wrong number of locals");
assert(locals->length() == cur_state->locals_size(), "wrong number of locals");
} else if (cur_scope->method()->max_locals() > 0) {
assert(cur_state->kind() == ValueStack::EmptyExceptionState, "should be");
nof_locals = cur_scope->method()->max_locals();
locals = new GrowableArray<ScopeValue*>(nof_locals);
for(int i = 0; i < nof_locals; i++) {
locals->append(_illegal_value);
}
}
// describe expression stack
int nof_stack = cur_state->stack_size();
if (nof_stack > 0) {
expressions = new GrowableArray<ScopeValue*>(nof_stack);
int pos = 0;
while (pos < nof_stack) {
Value expression = cur_state->stack_at_inc(pos);
append_scope_value(op_id, expression, expressions);
assert(expressions->length() == pos, "must match");
}
assert(expressions->length() == cur_state->stack_size(), "wrong number of stack entries");
}
// describe monitors
int nof_locks = cur_state->locks_size();
if (nof_locks > 0) {
int lock_offset = cur_state->caller_state() != NULL ? cur_state->caller_state()->total_locks_size() : 0;
monitors = new GrowableArray<MonitorValue*>(nof_locks);
for (int i = 0; i < nof_locks; i++) {
monitors->append(location_for_monitor_index(lock_offset + i));
}
}
return new IRScopeDebugInfo(cur_scope, cur_state->bci(), locals, expressions, monitors, caller_debug_info);
}
void LinearScan::compute_debug_info(CodeEmitInfo* info, int op_id) {
TRACE_LINEAR_SCAN(3, tty->print_cr("creating debug information at op_id %d", op_id));
IRScope* innermost_scope = info->scope();
ValueStack* innermost_state = info->stack();
assert(innermost_scope != NULL && innermost_state != NULL, "why is it missing?");
DEBUG_ONLY(check_stack_depth(info, innermost_state->stack_size()));
if (info->_scope_debug_info == NULL) {
// compute debug information
info->_scope_debug_info = compute_debug_info_for_scope(op_id, innermost_scope, innermost_state, innermost_state);
} else {
// debug information already set. Check that it is correct from the current point of view
DEBUG_ONLY(assert_equal(info->_scope_debug_info, compute_debug_info_for_scope(op_id, innermost_scope, innermost_state, innermost_state)));
}
}
void LinearScan::assign_reg_num(LIR_OpList* instructions, IntervalWalker* iw) {
LIR_OpVisitState visitor;
int num_inst = instructions->length();
bool has_dead = false;
for (int j = 0; j < num_inst; j++) {
LIR_Op* op = instructions->at(j);
if (op == NULL) { // this can happen when spill-moves are removed in eliminate_spill_moves
has_dead = true;
continue;
}
int op_id = op->id();
// visit instruction to get list of operands
visitor.visit(op);
// iterate all modes of the visitor and process all virtual operands
for_each_visitor_mode(mode) {
int n = visitor.opr_count(mode);
for (int k = 0; k < n; k++) {
LIR_Opr opr = visitor.opr_at(mode, k);
if (opr->is_virtual_register()) {
visitor.set_opr_at(mode, k, color_lir_opr(opr, op_id, mode));
}
}
}
if (visitor.info_count() > 0) {
// exception handling
if (compilation()->has_exception_handlers()) {
XHandlers* xhandlers = visitor.all_xhandler();
int n = xhandlers->length();
for (int k = 0; k < n; k++) {
XHandler* handler = xhandlers->handler_at(k);
if (handler->entry_code() != NULL) {
assign_reg_num(handler->entry_code()->instructions_list(), NULL);
}
}
} else {
assert(visitor.all_xhandler()->length() == 0, "missed exception handler");
}
// compute oop map
assert(iw != NULL, "needed for compute_oop_map");
compute_oop_map(iw, visitor, op);
// compute debug information
if (!use_fpu_stack_allocation()) {
// compute debug information if fpu stack allocation is not needed.
// when fpu stack allocation is needed, the debug information can not
// be computed here because the exact location of fpu operands is not known
// -> debug information is created inside the fpu stack allocator
int n = visitor.info_count();
for (int k = 0; k < n; k++) {
compute_debug_info(visitor.info_at(k), op_id);
}
}
}
#ifdef ASSERT
// make sure we haven't made the op invalid.
op->verify();
#endif
// remove useless moves
if (op->code() == lir_move) {
assert(op->as_Op1() != NULL, "move must be LIR_Op1");
LIR_Op1* move = (LIR_Op1*)op;
LIR_Opr src = move->in_opr();
LIR_Opr dst = move->result_opr();
if (dst == src ||
!dst->is_pointer() && !src->is_pointer() &&
src->is_same_register(dst)) {
instructions->at_put(j, NULL);
has_dead = true;
}
}
}
if (has_dead) {
// iterate all instructions of the block and remove all null-values.
int insert_point = 0;
for (int j = 0; j < num_inst; j++) {
LIR_Op* op = instructions->at(j);
if (op != NULL) {
if (insert_point != j) {
instructions->at_put(insert_point, op);
}
insert_point++;
}
}
instructions->truncate(insert_point);
}
}
void LinearScan::assign_reg_num() {
TIME_LINEAR_SCAN(timer_assign_reg_num);
init_compute_debug_info();
IntervalWalker* iw = init_compute_oop_maps();
int num_blocks = block_count();
for (int i = 0; i < num_blocks; i++) {
BlockBegin* block = block_at(i);
assign_reg_num(block->lir()->instructions_list(), iw);
}
}
void LinearScan::do_linear_scan() {
NOT_PRODUCT(_total_timer.begin_method());
number_instructions();
NOT_PRODUCT(print_lir(1, "Before Register Allocation"));
compute_local_live_sets();
compute_global_live_sets();
CHECK_BAILOUT();
build_intervals();
CHECK_BAILOUT();
sort_intervals_before_allocation();
NOT_PRODUCT(print_intervals("Before Register Allocation"));
NOT_PRODUCT(LinearScanStatistic::compute(this, _stat_before_alloc));
allocate_registers();
CHECK_BAILOUT();
resolve_data_flow();
if (compilation()->has_exception_handlers()) {
resolve_exception_handlers();
}
// fill in number of spill slots into frame_map
propagate_spill_slots();
CHECK_BAILOUT();
NOT_PRODUCT(print_intervals("After Register Allocation"));
NOT_PRODUCT(print_lir(2, "LIR after register allocation:"));
sort_intervals_after_allocation();
DEBUG_ONLY(verify());
eliminate_spill_moves();
assign_reg_num();
CHECK_BAILOUT();
NOT_PRODUCT(print_lir(2, "LIR after assignment of register numbers:"));
NOT_PRODUCT(LinearScanStatistic::compute(this, _stat_after_asign));
{ TIME_LINEAR_SCAN(timer_allocate_fpu_stack);
if (use_fpu_stack_allocation()) {
allocate_fpu_stack(); // Only has effect on Intel
NOT_PRODUCT(print_lir(2, "LIR after FPU stack allocation:"));
}
}
{ TIME_LINEAR_SCAN(timer_optimize_lir);
EdgeMoveOptimizer::optimize(ir()->code());
ControlFlowOptimizer::optimize(ir()->code());
// check that cfg is still correct after optimizations
ir()->verify();
}
NOT_PRODUCT(print_lir(1, "Before Code Generation", false));
NOT_PRODUCT(LinearScanStatistic::compute(this, _stat_final));
NOT_PRODUCT(_total_timer.end_method(this));
}
// ********** Printing functions
#ifndef PRODUCT
void LinearScan::print_timers(double total) {
_total_timer.print(total);
}
void LinearScan::print_statistics() {
_stat_before_alloc.print("before allocation");
_stat_after_asign.print("after assignment of register");
_stat_final.print("after optimization");
}
void LinearScan::print_bitmap(BitMap& b) {
for (unsigned int i = 0; i < b.size(); i++) {
if (b.at(i)) tty->print("%d ", i);
}
tty->cr();
}
void LinearScan::print_intervals(const char* label) {
if (TraceLinearScanLevel >= 1) {
int i;
tty->cr();
tty->print_cr("%s", label);
for (i = 0; i < interval_count(); i++) {
Interval* interval = interval_at(i);
if (interval != NULL) {
interval->print();
}
}
tty->cr();
tty->print_cr("--- Basic Blocks ---");
for (i = 0; i < block_count(); i++) {
BlockBegin* block = block_at(i);
tty->print("B%d [%d, %d, %d, %d] ", block->block_id(), block->first_lir_instruction_id(), block->last_lir_instruction_id(), block->loop_index(), block->loop_depth());
}
tty->cr();
tty->cr();
}
if (PrintCFGToFile) {
CFGPrinter::print_intervals(&_intervals, label);
}
}
void LinearScan::print_lir(int level, const char* label, bool hir_valid) {
if (TraceLinearScanLevel >= level) {
tty->cr();
tty->print_cr("%s", label);
print_LIR(ir()->linear_scan_order());
tty->cr();
}
if (level == 1 && PrintCFGToFile) {
CFGPrinter::print_cfg(ir()->linear_scan_order(), label, hir_valid, true);
}
}
#endif //PRODUCT
// ********** verification functions for allocation
// (check that all intervals have a correct register and that no registers are overwritten)
#ifdef ASSERT
void LinearScan::verify() {
TRACE_LINEAR_SCAN(2, tty->print_cr("********* verifying intervals ******************************************"));
verify_intervals();
TRACE_LINEAR_SCAN(2, tty->print_cr("********* verifying that no oops are in fixed intervals ****************"));
verify_no_oops_in_fixed_intervals();
TRACE_LINEAR_SCAN(2, tty->print_cr("********* verifying that unpinned constants are not alive across block boundaries"));
verify_constants();
TRACE_LINEAR_SCAN(2, tty->print_cr("********* verifying register allocation ********************************"));
verify_registers();
TRACE_LINEAR_SCAN(2, tty->print_cr("********* no errors found **********************************************"));
}
void LinearScan::verify_intervals() {
int len = interval_count();
bool has_error = false;
for (int i = 0; i < len; i++) {
Interval* i1 = interval_at(i);
if (i1 == NULL) continue;
i1->check_split_children();
if (i1->reg_num() != i) {
tty->print_cr("Interval %d is on position %d in list", i1->reg_num(), i); i1->print(); tty->cr();
has_error = true;
}
if (i1->reg_num() >= LIR_OprDesc::vreg_base && i1->type() == T_ILLEGAL) {
tty->print_cr("Interval %d has no type assigned", i1->reg_num()); i1->print(); tty->cr();
has_error = true;
}
if (i1->assigned_reg() == any_reg) {
tty->print_cr("Interval %d has no register assigned", i1->reg_num()); i1->print(); tty->cr();
has_error = true;
}
if (i1->assigned_reg() == i1->assigned_regHi()) {
tty->print_cr("Interval %d: low and high register equal", i1->reg_num()); i1->print(); tty->cr();
has_error = true;
}
if (!is_processed_reg_num(i1->assigned_reg())) {
tty->print_cr("Can not have an Interval for an ignored register"); i1->print(); tty->cr();
has_error = true;
}
if (i1->first() == Range::end()) {
tty->print_cr("Interval %d has no Range", i1->reg_num()); i1->print(); tty->cr();
has_error = true;
}
for (Range* r = i1->first(); r != Range::end(); r = r->next()) {
if (r->from() >= r->to()) {
tty->print_cr("Interval %d has zero length range", i1->reg_num()); i1->print(); tty->cr();
has_error = true;
}
}
for (int j = i + 1; j < len; j++) {
Interval* i2 = interval_at(j);
if (i2 == NULL) continue;
// special intervals that are created in MoveResolver
// -> ignore them because the range information has no meaning there
if (i1->from() == 1 && i1->to() == 2) continue;
if (i2->from() == 1 && i2->to() == 2) continue;
int r1 = i1->assigned_reg();
int r1Hi = i1->assigned_regHi();
int r2 = i2->assigned_reg();
int r2Hi = i2->assigned_regHi();
if (i1->intersects(i2) && (r1 == r2 || r1 == r2Hi || (r1Hi != any_reg && (r1Hi == r2 || r1Hi == r2Hi)))) {
tty->print_cr("Intervals %d and %d overlap and have the same register assigned", i1->reg_num(), i2->reg_num());
i1->print(); tty->cr();
i2->print(); tty->cr();
has_error = true;
}
}
}
assert(has_error == false, "register allocation invalid");
}
void LinearScan::verify_no_oops_in_fixed_intervals() {
Interval* fixed_intervals;
Interval* other_intervals;
create_unhandled_lists(&fixed_intervals, &other_intervals, is_precolored_cpu_interval, NULL);
// to ensure a walking until the last instruction id, add a dummy interval
// with a high operation id
other_intervals = new Interval(any_reg);
other_intervals->add_range(max_jint - 2, max_jint - 1);
IntervalWalker* iw = new IntervalWalker(this, fixed_intervals, other_intervals);
LIR_OpVisitState visitor;
for (int i = 0; i < block_count(); i++) {
BlockBegin* block = block_at(i);
LIR_OpList* instructions = block->lir()->instructions_list();
for (int j = 0; j < instructions->length(); j++) {
LIR_Op* op = instructions->at(j);
int op_id = op->id();
visitor.visit(op);
if (visitor.info_count() > 0) {
iw->walk_before(op->id());
bool check_live = true;
if (op->code() == lir_move) {
LIR_Op1* move = (LIR_Op1*)op;
check_live = (move->patch_code() == lir_patch_none);
}
LIR_OpBranch* branch = op->as_OpBranch();
if (branch != NULL && branch->stub() != NULL && branch->stub()->is_exception_throw_stub()) {
// Don't bother checking the stub in this case since the
// exception stub will never return to normal control flow.
check_live = false;
}
// Make sure none of the fixed registers is live across an
// oopmap since we can't handle that correctly.
if (check_live) {
for (Interval* interval = iw->active_first(fixedKind);
interval != Interval::end();
interval = interval->next()) {
if (interval->current_to() > op->id() + 1) {
// This interval is live out of this op so make sure
// that this interval represents some value that's
// referenced by this op either as an input or output.
bool ok = false;
for_each_visitor_mode(mode) {
int n = visitor.opr_count(mode);
for (int k = 0; k < n; k++) {
LIR_Opr opr = visitor.opr_at(mode, k);
if (opr->is_fixed_cpu()) {
if (interval_at(reg_num(opr)) == interval) {
ok = true;
break;
}
int hi = reg_numHi(opr);
if (hi != -1 && interval_at(hi) == interval) {
ok = true;
break;
}
}
}
}
assert(ok, "fixed intervals should never be live across an oopmap point");
}
}
}
}
// oop-maps at calls do not contain registers, so check is not needed
if (!visitor.has_call()) {
for_each_visitor_mode(mode) {
int n = visitor.opr_count(mode);
for (int k = 0; k < n; k++) {
LIR_Opr opr = visitor.opr_at(mode, k);
if (opr->is_fixed_cpu() && opr->is_oop()) {
// operand is a non-virtual cpu register and contains an oop
TRACE_LINEAR_SCAN(4, op->print_on(tty); tty->print("checking operand "); opr->print(); tty->cr());
Interval* interval = interval_at(reg_num(opr));
assert(interval != NULL, "no interval");
if (mode == LIR_OpVisitState::inputMode) {
if (interval->to() >= op_id + 1) {
assert(interval->to() < op_id + 2 ||
interval->has_hole_between(op_id, op_id + 2),
"oop input operand live after instruction");
}
} else if (mode == LIR_OpVisitState::outputMode) {
if (interval->from() <= op_id - 1) {
assert(interval->has_hole_between(op_id - 1, op_id),
"oop input operand live after instruction");
}
}
}
}
}
}
}
}
}
void LinearScan::verify_constants() {
int num_regs = num_virtual_regs();
int size = live_set_size();
int num_blocks = block_count();
for (int i = 0; i < num_blocks; i++) {
BlockBegin* block = block_at(i);
BitMap live_at_edge = block->live_in();
// visit all registers where the live_at_edge bit is set
for (int r = (int)live_at_edge.get_next_one_offset(0, size); r < size; r = (int)live_at_edge.get_next_one_offset(r + 1, size)) {
TRACE_LINEAR_SCAN(4, tty->print("checking interval %d of block B%d", r, block->block_id()));
Value value = gen()->instruction_for_vreg(r);
assert(value != NULL, "all intervals live across block boundaries must have Value");
assert(value->operand()->is_register() && value->operand()->is_virtual(), "value must have virtual operand");
assert(value->operand()->vreg_number() == r, "register number must match");
// TKR assert(value->as_Constant() == NULL || value->is_pinned(), "only pinned constants can be alive accross block boundaries");
}
}
}
class RegisterVerifier: public StackObj {
private:
LinearScan* _allocator;
BlockList _work_list; // all blocks that must be processed
IntervalsList _saved_states; // saved information of previous check
// simplified access to methods of LinearScan
Compilation* compilation() const { return _allocator->compilation(); }
Interval* interval_at(int reg_num) const { return _allocator->interval_at(reg_num); }
int reg_num(LIR_Opr opr) const { return _allocator->reg_num(opr); }
// currently, only registers are processed
int state_size() { return LinearScan::nof_regs; }
// accessors
IntervalList* state_for_block(BlockBegin* block) { return _saved_states.at(block->block_id()); }
void set_state_for_block(BlockBegin* block, IntervalList* saved_state) { _saved_states.at_put(block->block_id(), saved_state); }
void add_to_work_list(BlockBegin* block) { if (!_work_list.contains(block)) _work_list.append(block); }
// helper functions
IntervalList* copy(IntervalList* input_state);
void state_put(IntervalList* input_state, int reg, Interval* interval);
bool check_state(IntervalList* input_state, int reg, Interval* interval);
void process_block(BlockBegin* block);
void process_xhandler(XHandler* xhandler, IntervalList* input_state);
void process_successor(BlockBegin* block, IntervalList* input_state);
void process_operations(LIR_List* ops, IntervalList* input_state);
public:
RegisterVerifier(LinearScan* allocator)
: _allocator(allocator)
, _work_list(16)
, _saved_states(BlockBegin::number_of_blocks(), NULL)
{ }
void verify(BlockBegin* start);
};
// entry function from LinearScan that starts the verification
void LinearScan::verify_registers() {
RegisterVerifier verifier(this);
verifier.verify(block_at(0));
}
void RegisterVerifier::verify(BlockBegin* start) {
// setup input registers (method arguments) for first block
IntervalList* input_state = new IntervalList(state_size(), NULL);
CallingConvention* args = compilation()->frame_map()->incoming_arguments();
for (int n = 0; n < args->length(); n++) {
LIR_Opr opr = args->at(n);
if (opr->is_register()) {
Interval* interval = interval_at(reg_num(opr));
if (interval->assigned_reg() < state_size()) {
input_state->at_put(interval->assigned_reg(), interval);
}
if (interval->assigned_regHi() != LinearScan::any_reg && interval->assigned_regHi() < state_size()) {
input_state->at_put(interval->assigned_regHi(), interval);
}
}
}
set_state_for_block(start, input_state);
add_to_work_list(start);
// main loop for verification
do {
BlockBegin* block = _work_list.at(0);
_work_list.remove_at(0);
process_block(block);
} while (!_work_list.is_empty());
}
void RegisterVerifier::process_block(BlockBegin* block) {
TRACE_LINEAR_SCAN(2, tty->cr(); tty->print_cr("process_block B%d", block->block_id()));
// must copy state because it is modified
IntervalList* input_state = copy(state_for_block(block));
if (TraceLinearScanLevel >= 4) {
tty->print_cr("Input-State of intervals:");
tty->print(" ");
for (int i = 0; i < state_size(); i++) {
if (input_state->at(i) != NULL) {
tty->print(" %4d", input_state->at(i)->reg_num());
} else {
tty->print(" __");
}
}
tty->cr();
tty->cr();
}
// process all operations of the block
process_operations(block->lir(), input_state);
// iterate all successors
for (int i = 0; i < block->number_of_sux(); i++) {
process_successor(block->sux_at(i), input_state);
}
}
void RegisterVerifier::process_xhandler(XHandler* xhandler, IntervalList* input_state) {
TRACE_LINEAR_SCAN(2, tty->print_cr("process_xhandler B%d", xhandler->entry_block()->block_id()));
// must copy state because it is modified
input_state = copy(input_state);
if (xhandler->entry_code() != NULL) {
process_operations(xhandler->entry_code(), input_state);
}
process_successor(xhandler->entry_block(), input_state);
}
void RegisterVerifier::process_successor(BlockBegin* block, IntervalList* input_state) {
IntervalList* saved_state = state_for_block(block);
if (saved_state != NULL) {
// this block was already processed before.
// check if new input_state is consistent with saved_state
bool saved_state_correct = true;
for (int i = 0; i < state_size(); i++) {
if (input_state->at(i) != saved_state->at(i)) {
// current input_state and previous saved_state assume a different
// interval in this register -> assume that this register is invalid
if (saved_state->at(i) != NULL) {
// invalidate old calculation only if it assumed that
// register was valid. when the register was already invalid,
// then the old calculation was correct.
saved_state_correct = false;
saved_state->at_put(i, NULL);
TRACE_LINEAR_SCAN(4, tty->print_cr("process_successor B%d: invalidating slot %d", block->block_id(), i));
}
}
}
if (saved_state_correct) {
// already processed block with correct input_state
TRACE_LINEAR_SCAN(2, tty->print_cr("process_successor B%d: previous visit already correct", block->block_id()));
} else {
// must re-visit this block
TRACE_LINEAR_SCAN(2, tty->print_cr("process_successor B%d: must re-visit because input state changed", block->block_id()));
add_to_work_list(block);
}
} else {
// block was not processed before, so set initial input_state
TRACE_LINEAR_SCAN(2, tty->print_cr("process_successor B%d: initial visit", block->block_id()));
set_state_for_block(block, copy(input_state));
add_to_work_list(block);
}
}
IntervalList* RegisterVerifier::copy(IntervalList* input_state) {
IntervalList* copy_state = new IntervalList(input_state->length());
copy_state->push_all(input_state);
return copy_state;
}
void RegisterVerifier::state_put(IntervalList* input_state, int reg, Interval* interval) {
if (reg != LinearScan::any_reg && reg < state_size()) {
if (interval != NULL) {
TRACE_LINEAR_SCAN(4, tty->print_cr(" reg[%d] = %d", reg, interval->reg_num()));
} else if (input_state->at(reg) != NULL) {
TRACE_LINEAR_SCAN(4, tty->print_cr(" reg[%d] = NULL", reg));
}
input_state->at_put(reg, interval);
}
}
bool RegisterVerifier::check_state(IntervalList* input_state, int reg, Interval* interval) {
if (reg != LinearScan::any_reg && reg < state_size()) {
if (input_state->at(reg) != interval) {
tty->print_cr("!! Error in register allocation: register %d does not contain interval %d", reg, interval->reg_num());
return true;
}
}
return false;
}
void RegisterVerifier::process_operations(LIR_List* ops, IntervalList* input_state) {
// visit all instructions of the block
LIR_OpVisitState visitor;
bool has_error = false;
for (int i = 0; i < ops->length(); i++) {
LIR_Op* op = ops->at(i);
visitor.visit(op);
TRACE_LINEAR_SCAN(4, op->print_on(tty));
// check if input operands are correct
int j;
int n = visitor.opr_count(LIR_OpVisitState::inputMode);
for (j = 0; j < n; j++) {
LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::inputMode, j);
if (opr->is_register() && LinearScan::is_processed_reg_num(reg_num(opr))) {
Interval* interval = interval_at(reg_num(opr));
if (op->id() != -1) {
interval = interval->split_child_at_op_id(op->id(), LIR_OpVisitState::inputMode);
}
has_error |= check_state(input_state, interval->assigned_reg(), interval->split_parent());
has_error |= check_state(input_state, interval->assigned_regHi(), interval->split_parent());
// When an operand is marked with is_last_use, then the fpu stack allocator
// removes the register from the fpu stack -> the register contains no value
if (opr->is_last_use()) {
state_put(input_state, interval->assigned_reg(), NULL);
state_put(input_state, interval->assigned_regHi(), NULL);
}
}
}
// invalidate all caller save registers at calls
if (visitor.has_call()) {
for (j = 0; j < FrameMap::nof_caller_save_cpu_regs(); j++) {
state_put(input_state, reg_num(FrameMap::caller_save_cpu_reg_at(j)), NULL);
}
for (j = 0; j < FrameMap::nof_caller_save_fpu_regs; j++) {
state_put(input_state, reg_num(FrameMap::caller_save_fpu_reg_at(j)), NULL);
}
#ifdef X86
for (j = 0; j < FrameMap::nof_caller_save_xmm_regs; j++) {
state_put(input_state, reg_num(FrameMap::caller_save_xmm_reg_at(j)), NULL);
}
#endif
}
// process xhandler before output and temp operands
XHandlers* xhandlers = visitor.all_xhandler();
n = xhandlers->length();
for (int k = 0; k < n; k++) {
process_xhandler(xhandlers->handler_at(k), input_state);
}
// set temp operands (some operations use temp operands also as output operands, so can't set them NULL)
n = visitor.opr_count(LIR_OpVisitState::tempMode);
for (j = 0; j < n; j++) {
LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::tempMode, j);
if (opr->is_register() && LinearScan::is_processed_reg_num(reg_num(opr))) {
Interval* interval = interval_at(reg_num(opr));
if (op->id() != -1) {
interval = interval->split_child_at_op_id(op->id(), LIR_OpVisitState::tempMode);
}
state_put(input_state, interval->assigned_reg(), interval->split_parent());
state_put(input_state, interval->assigned_regHi(), interval->split_parent());
}
}
// set output operands
n = visitor.opr_count(LIR_OpVisitState::outputMode);
for (j = 0; j < n; j++) {
LIR_Opr opr = visitor.opr_at(LIR_OpVisitState::outputMode, j);
if (opr->is_register() && LinearScan::is_processed_reg_num(reg_num(opr))) {
Interval* interval = interval_at(reg_num(opr));
if (op->id() != -1) {
interval = interval->split_child_at_op_id(op->id(), LIR_OpVisitState::outputMode);
}
state_put(input_state, interval->assigned_reg(), interval->split_parent());
state_put(input_state, interval->assigned_regHi(), interval->split_parent());
}
}
}
assert(has_error == false, "Error in register allocation");
}
#endif // ASSERT
// **** Implementation of MoveResolver ******************************
MoveResolver::MoveResolver(LinearScan* allocator) :
_allocator(allocator),
_multiple_reads_allowed(false),
_mapping_from(8),
_mapping_from_opr(8),
_mapping_to(8),
_insert_list(NULL),
_insert_idx(-1),
_insertion_buffer()
{
for (int i = 0; i < LinearScan::nof_regs; i++) {
_register_blocked[i] = 0;
}
DEBUG_ONLY(check_empty());
}
#ifdef ASSERT
void MoveResolver::check_empty() {
assert(_mapping_from.length() == 0 && _mapping_from_opr.length() == 0 && _mapping_to.length() == 0, "list must be empty before and after processing");
for (int i = 0; i < LinearScan::nof_regs; i++) {
assert(register_blocked(i) == 0, "register map must be empty before and after processing");
}
assert(_multiple_reads_allowed == false, "must have default value");
}
void MoveResolver::verify_before_resolve() {
assert(_mapping_from.length() == _mapping_from_opr.length(), "length must be equal");
assert(_mapping_from.length() == _mapping_to.length(), "length must be equal");
assert(_insert_list != NULL && _insert_idx != -1, "insert position not set");
int i, j;
if (!_multiple_reads_allowed) {
for (i = 0; i < _mapping_from.length(); i++) {
for (j = i + 1; j < _mapping_from.length(); j++) {
assert(_mapping_from.at(i) == NULL || _mapping_from.at(i) != _mapping_from.at(j), "cannot read from same interval twice");
}
}
}
for (i = 0; i < _mapping_to.length(); i++) {
for (j = i + 1; j < _mapping_to.length(); j++) {
assert(_mapping_to.at(i) != _mapping_to.at(j), "cannot write to same interval twice");
}
}
BitMap used_regs(LinearScan::nof_regs + allocator()->frame_map()->argcount() + allocator()->max_spills());
used_regs.clear();
if (!_multiple_reads_allowed) {
for (i = 0; i < _mapping_from.length(); i++) {
Interval* it = _mapping_from.at(i);
if (it != NULL) {
assert(!used_regs.at(it->assigned_reg()), "cannot read from same register twice");
used_regs.set_bit(it->assigned_reg());
if (it->assigned_regHi() != LinearScan::any_reg) {
assert(!used_regs.at(it->assigned_regHi()), "cannot read from same register twice");
used_regs.set_bit(it->assigned_regHi());
}
}
}
}
used_regs.clear();
for (i = 0; i < _mapping_to.length(); i++) {
Interval* it = _mapping_to.at(i);
assert(!used_regs.at(it->assigned_reg()), "cannot write to same register twice");
used_regs.set_bit(it->assigned_reg());
if (it->assigned_regHi() != LinearScan::any_reg) {
assert(!used_regs.at(it->assigned_regHi()), "cannot write to same register twice");
used_regs.set_bit(it->assigned_regHi());
}
}
used_regs.clear();
for (i = 0; i < _mapping_from.length(); i++) {
Interval* it = _mapping_from.at(i);
if (it != NULL && it->assigned_reg() >= LinearScan::nof_regs) {
used_regs.set_bit(it->assigned_reg());
}
}
for (i = 0; i < _mapping_to.length(); i++) {
Interval* it = _mapping_to.at(i);
assert(!used_regs.at(it->assigned_reg()) || it->assigned_reg() == _mapping_from.at(i)->assigned_reg(), "stack slots used in _mapping_from must be disjoint to _mapping_to");
}
}
#endif // ASSERT
// mark assigned_reg and assigned_regHi of the interval as blocked
void MoveResolver::block_registers(Interval* it) {
int reg = it->assigned_reg();
if (reg < LinearScan::nof_regs) {
assert(_multiple_reads_allowed || register_blocked(reg) == 0, "register already marked as used");
set_register_blocked(reg, 1);
}
reg = it->assigned_regHi();
if (reg != LinearScan::any_reg && reg < LinearScan::nof_regs) {
assert(_multiple_reads_allowed || register_blocked(reg) == 0, "register already marked as used");
set_register_blocked(reg, 1);
}
}
// mark assigned_reg and assigned_regHi of the interval as unblocked
void MoveResolver::unblock_registers(Interval* it) {
int reg = it->assigned_reg();
if (reg < LinearScan::nof_regs) {
assert(register_blocked(reg) > 0, "register already marked as unused");
set_register_blocked(reg, -1);
}
reg = it->assigned_regHi();
if (reg != LinearScan::any_reg && reg < LinearScan::nof_regs) {
assert(register_blocked(reg) > 0, "register already marked as unused");
set_register_blocked(reg, -1);
}
}
// check if assigned_reg and assigned_regHi of the to-interval are not blocked (or only blocked by from)
bool MoveResolver::save_to_process_move(Interval* from, Interval* to) {
int from_reg = -1;
int from_regHi = -1;
if (from != NULL) {
from_reg = from->assigned_reg();
from_regHi = from->assigned_regHi();
}
int reg = to->assigned_reg();
if (reg < LinearScan::nof_regs) {
if (register_blocked(reg) > 1 || (register_blocked(reg) == 1 && reg != from_reg && reg != from_regHi)) {
return false;
}
}
reg = to->assigned_regHi();
if (reg != LinearScan::any_reg && reg < LinearScan::nof_regs) {
if (register_blocked(reg) > 1 || (register_blocked(reg) == 1 && reg != from_reg && reg != from_regHi)) {
return false;
}
}
return true;
}
void MoveResolver::create_insertion_buffer(LIR_List* list) {
assert(!_insertion_buffer.initialized(), "overwriting existing buffer");
_insertion_buffer.init(list);
}
void MoveResolver::append_insertion_buffer() {
if (_insertion_buffer.initialized()) {
_insertion_buffer.lir_list()->append(&_insertion_buffer);
}
assert(!_insertion_buffer.initialized(), "must be uninitialized now");
_insert_list = NULL;
_insert_idx = -1;
}
void MoveResolver::insert_move(Interval* from_interval, Interval* to_interval) {
assert(from_interval->reg_num() != to_interval->reg_num(), "from and to interval equal");
assert(from_interval->type() == to_interval->type(), "move between different types");
assert(_insert_list != NULL && _insert_idx != -1, "must setup insert position first");
assert(_insertion_buffer.lir_list() == _insert_list, "wrong insertion buffer");
LIR_Opr from_opr = LIR_OprFact::virtual_register(from_interval->reg_num(), from_interval->type());
LIR_Opr to_opr = LIR_OprFact::virtual_register(to_interval->reg_num(), to_interval->type());
if (!_multiple_reads_allowed) {
// the last_use flag is an optimization for FPU stack allocation. When the same
// input interval is used in more than one move, then it is too difficult to determine
// if this move is really the last use.
from_opr = from_opr->make_last_use();
}
_insertion_buffer.move(_insert_idx, from_opr, to_opr);
TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: inserted move from register %d (%d, %d) to %d (%d, %d)", from_interval->reg_num(), from_interval->assigned_reg(), from_interval->assigned_regHi(), to_interval->reg_num(), to_interval->assigned_reg(), to_interval->assigned_regHi()));
}
void MoveResolver::insert_move(LIR_Opr from_opr, Interval* to_interval) {
assert(from_opr->type() == to_interval->type(), "move between different types");
assert(_insert_list != NULL && _insert_idx != -1, "must setup insert position first");
assert(_insertion_buffer.lir_list() == _insert_list, "wrong insertion buffer");
LIR_Opr to_opr = LIR_OprFact::virtual_register(to_interval->reg_num(), to_interval->type());
_insertion_buffer.move(_insert_idx, from_opr, to_opr);
TRACE_LINEAR_SCAN(4, tty->print("MoveResolver: inserted move from constant "); from_opr->print(); tty->print_cr(" to %d (%d, %d)", to_interval->reg_num(), to_interval->assigned_reg(), to_interval->assigned_regHi()));
}
void MoveResolver::resolve_mappings() {
TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: resolving mappings for Block B%d, index %d", _insert_list->block() != NULL ? _insert_list->block()->block_id() : -1, _insert_idx));
DEBUG_ONLY(verify_before_resolve());
// Block all registers that are used as input operands of a move.
// When a register is blocked, no move to this register is emitted.
// This is necessary for detecting cycles in moves.
int i;
for (i = _mapping_from.length() - 1; i >= 0; i--) {
Interval* from_interval = _mapping_from.at(i);
if (from_interval != NULL) {
block_registers(from_interval);
}
}
int spill_candidate = -1;
while (_mapping_from.length() > 0) {
bool processed_interval = false;
for (i = _mapping_from.length() - 1; i >= 0; i--) {
Interval* from_interval = _mapping_from.at(i);
Interval* to_interval = _mapping_to.at(i);
if (save_to_process_move(from_interval, to_interval)) {
// this inverval can be processed because target is free
if (from_interval != NULL) {
insert_move(from_interval, to_interval);
unblock_registers(from_interval);
} else {
insert_move(_mapping_from_opr.at(i), to_interval);
}
_mapping_from.remove_at(i);
_mapping_from_opr.remove_at(i);
_mapping_to.remove_at(i);
processed_interval = true;
} else if (from_interval != NULL && from_interval->assigned_reg() < LinearScan::nof_regs) {
// this interval cannot be processed now because target is not free
// it starts in a register, so it is a possible candidate for spilling
spill_candidate = i;
}
}
if (!processed_interval) {
// no move could be processed because there is a cycle in the move list
// (e.g. r1 -> r2, r2 -> r1), so one interval must be spilled to memory
assert(spill_candidate != -1, "no interval in register for spilling found");
// create a new spill interval and assign a stack slot to it
Interval* from_interval = _mapping_from.at(spill_candidate);
Interval* spill_interval = new Interval(-1);
spill_interval->set_type(from_interval->type());
// add a dummy range because real position is difficult to calculate
// Note: this range is a special case when the integrity of the allocation is checked
spill_interval->add_range(1, 2);
// do not allocate a new spill slot for temporary interval, but
// use spill slot assigned to from_interval. Otherwise moves from
// one stack slot to another can happen (not allowed by LIR_Assembler
int spill_slot = from_interval->canonical_spill_slot();
if (spill_slot < 0) {
spill_slot = allocator()->allocate_spill_slot(type2spill_size[spill_interval->type()] == 2);
from_interval->set_canonical_spill_slot(spill_slot);
}
spill_interval->assign_reg(spill_slot);
allocator()->append_interval(spill_interval);
TRACE_LINEAR_SCAN(4, tty->print_cr("created new Interval %d for spilling", spill_interval->reg_num()));
// insert a move from register to stack and update the mapping
insert_move(from_interval, spill_interval);
_mapping_from.at_put(spill_candidate, spill_interval);
unblock_registers(from_interval);
}
}
// reset to default value
_multiple_reads_allowed = false;
// check that all intervals have been processed
DEBUG_ONLY(check_empty());
}
void MoveResolver::set_insert_position(LIR_List* insert_list, int insert_idx) {
TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: setting insert position to Block B%d, index %d", insert_list->block() != NULL ? insert_list->block()->block_id() : -1, insert_idx));
assert(_insert_list == NULL && _insert_idx == -1, "use move_insert_position instead of set_insert_position when data already set");
create_insertion_buffer(insert_list);
_insert_list = insert_list;
_insert_idx = insert_idx;
}
void MoveResolver::move_insert_position(LIR_List* insert_list, int insert_idx) {
TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: moving insert position to Block B%d, index %d", insert_list->block() != NULL ? insert_list->block()->block_id() : -1, insert_idx));
if (_insert_list != NULL && (insert_list != _insert_list || insert_idx != _insert_idx)) {
// insert position changed -> resolve current mappings
resolve_mappings();
}
if (insert_list != _insert_list) {
// block changed -> append insertion_buffer because it is
// bound to a specific block and create a new insertion_buffer
append_insertion_buffer();
create_insertion_buffer(insert_list);
}
_insert_list = insert_list;
_insert_idx = insert_idx;
}
void MoveResolver::add_mapping(Interval* from_interval, Interval* to_interval) {
TRACE_LINEAR_SCAN(4, tty->print_cr("MoveResolver: adding mapping from %d (%d, %d) to %d (%d, %d)", from_interval->reg_num(), from_interval->assigned_reg(), from_interval->assigned_regHi(), to_interval->reg_num(), to_interval->assigned_reg(), to_interval->assigned_regHi()));
_mapping_from.append(from_interval);
_mapping_from_opr.append(LIR_OprFact::illegalOpr);
_mapping_to.append(to_interval);
}
void MoveResolver::add_mapping(LIR_Opr from_opr, Interval* to_interval) {
TRACE_LINEAR_SCAN(4, tty->print("MoveResolver: adding mapping from "); from_opr->print(); tty->print_cr(" to %d (%d, %d)", to_interval->reg_num(), to_interval->assigned_reg(), to_interval->assigned_regHi()));
assert(from_opr->is_constant(), "only for constants");
_mapping_from.append(NULL);
_mapping_from_opr.append(from_opr);
_mapping_to.append(to_interval);
}
void MoveResolver::resolve_and_append_moves() {
if (has_mappings()) {
resolve_mappings();
}
append_insertion_buffer();
}
// **** Implementation of Range *************************************
Range::Range(int from, int to, Range* next) :
_from(from),
_to(to),
_next(next)
{
}
// initialize sentinel
Range* Range::_end = NULL;
void Range::initialize(Arena* arena) {
_end = new (arena) Range(max_jint, max_jint, NULL);
}
int Range::intersects_at(Range* r2) const {
const Range* r1 = this;
assert(r1 != NULL && r2 != NULL, "null ranges not allowed");
assert(r1 != _end && r2 != _end, "empty ranges not allowed");
do {
if (r1->from() < r2->from()) {
if (r1->to() <= r2->from()) {
r1 = r1->next(); if (r1 == _end) return -1;
} else {
return r2->from();
}
} else if (r2->from() < r1->from()) {
if (r2->to() <= r1->from()) {
r2 = r2->next(); if (r2 == _end) return -1;
} else {
return r1->from();
}
} else { // r1->from() == r2->from()
if (r1->from() == r1->to()) {
r1 = r1->next(); if (r1 == _end) return -1;
} else if (r2->from() == r2->to()) {
r2 = r2->next(); if (r2 == _end) return -1;
} else {
return r1->from();
}
}
} while (true);
}
#ifndef PRODUCT
void Range::print(outputStream* out) const {
out->print("[%d, %d[ ", _from, _to);
}
#endif
// **** Implementation of Interval **********************************
// initialize sentinel
Interval* Interval::_end = NULL;
void Interval::initialize(Arena* arena) {
Range::initialize(arena);
_end = new (arena) Interval(-1);
}
Interval::Interval(int reg_num) :
_reg_num(reg_num),
_type(T_ILLEGAL),
_first(Range::end()),
_use_pos_and_kinds(12),
_current(Range::end()),
_next(_end),
_state(invalidState),
_assigned_reg(LinearScan::any_reg),
_assigned_regHi(LinearScan::any_reg),
_cached_to(-1),
_cached_opr(LIR_OprFact::illegalOpr),
_cached_vm_reg(VMRegImpl::Bad()),
_split_children(0),
_canonical_spill_slot(-1),
_insert_move_when_activated(false),
_register_hint(NULL),
_spill_state(noDefinitionFound),
_spill_definition_pos(-1)
{
_split_parent = this;
_current_split_child = this;
}
int Interval::calc_to() {
assert(_first != Range::end(), "interval has no range");
Range* r = _first;
while (r->next() != Range::end()) {
r = r->next();
}
return r->to();
}
#ifdef ASSERT
// consistency check of split-children
void Interval::check_split_children() {
if (_split_children.length() > 0) {
assert(is_split_parent(), "only split parents can have children");
for (int i = 0; i < _split_children.length(); i++) {
Interval* i1 = _split_children.at(i);
assert(i1->split_parent() == this, "not a split child of this interval");
assert(i1->type() == type(), "must be equal for all split children");
assert(i1->canonical_spill_slot() == canonical_spill_slot(), "must be equal for all split children");
for (int j = i + 1; j < _split_children.length(); j++) {
Interval* i2 = _split_children.at(j);
assert(i1->reg_num() != i2->reg_num(), "same register number");
if (i1->from() < i2->from()) {
assert(i1->to() <= i2->from() && i1->to() < i2->to(), "intervals overlapping");
} else {
assert(i2->from() < i1->from(), "intervals start at same op_id");
assert(i2->to() <= i1->from() && i2->to() < i1->to(), "intervals overlapping");
}
}
}
}
}
#endif // ASSERT
Interval* Interval::register_hint(bool search_split_child) const {
if (!search_split_child) {
return _register_hint;
}
if (_register_hint != NULL) {
assert(_register_hint->is_split_parent(), "ony split parents are valid hint registers");
if (_register_hint->assigned_reg() >= 0 && _register_hint->assigned_reg() < LinearScan::nof_regs) {
return _register_hint;
} else if (_register_hint->_split_children.length() > 0) {
// search the first split child that has a register assigned
int len = _register_hint->_split_children.length();
for (int i = 0; i < len; i++) {
Interval* cur = _register_hint->_split_children.at(i);
if (cur->assigned_reg() >= 0 && cur->assigned_reg() < LinearScan::nof_regs) {
return cur;
}
}
}
}
// no hint interval found that has a register assigned
return NULL;
}
Interval* Interval::split_child_at_op_id(int op_id, LIR_OpVisitState::OprMode mode) {
assert(is_split_parent(), "can only be called for split parents");
assert(op_id >= 0, "invalid op_id (method can not be called for spill moves)");
Interval* result;
if (_split_children.length() == 0) {
result = this;
} else {
result = NULL;
int len = _split_children.length();
// in outputMode, the end of the interval (op_id == cur->to()) is not valid
int to_offset = (mode == LIR_OpVisitState::outputMode ? 0 : 1);
int i;
for (i = 0; i < len; i++) {
Interval* cur = _split_children.at(i);
if (cur->from() <= op_id && op_id < cur->to() + to_offset) {
if (i > 0) {
// exchange current split child to start of list (faster access for next call)
_split_children.at_put(i, _split_children.at(0));
_split_children.at_put(0, cur);
}
// interval found
result = cur;
break;
}
}
#ifdef ASSERT
for (i = 0; i < len; i++) {
Interval* tmp = _split_children.at(i);
if (tmp != result && tmp->from() <= op_id && op_id < tmp->to() + to_offset) {
tty->print_cr("two valid result intervals found for op_id %d: %d and %d", op_id, result->reg_num(), tmp->reg_num());
result->print();
tmp->print();
assert(false, "two valid result intervals found");
}
}
#endif
}
assert(result != NULL, "no matching interval found");
assert(result->covers(op_id, mode), "op_id not covered by interval");
return result;
}
// returns the last split child that ends before the given op_id
Interval* Interval::split_child_before_op_id(int op_id) {
assert(op_id >= 0, "invalid op_id");
Interval* parent = split_parent();
Interval* result = NULL;
int len = parent->_split_children.length();
assert(len > 0, "no split children available");
for (int i = len - 1; i >= 0; i--) {
Interval* cur = parent->_split_children.at(i);
if (cur->to() <= op_id && (result == NULL || result->to() < cur->to())) {
result = cur;
}
}
assert(result != NULL, "no split child found");
return result;
}
// checks if op_id is covered by any split child
bool Interval::split_child_covers(int op_id, LIR_OpVisitState::OprMode mode) {
assert(is_split_parent(), "can only be called for split parents");
assert(op_id >= 0, "invalid op_id (method can not be called for spill moves)");
if (_split_children.length() == 0) {
// simple case if interval was not split
return covers(op_id, mode);
} else {
// extended case: check all split children
int len = _split_children.length();
for (int i = 0; i < len; i++) {
Interval* cur = _split_children.at(i);
if (cur->covers(op_id, mode)) {
return true;
}
}
return false;
}
}
// Note: use positions are sorted descending -> first use has highest index
int Interval::first_usage(IntervalUseKind min_use_kind) const {
assert(LinearScan::is_virtual_interval(this), "cannot access use positions for fixed intervals");
for (int i = _use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
if (_use_pos_and_kinds.at(i + 1) >= min_use_kind) {
return _use_pos_and_kinds.at(i);
}
}
return max_jint;
}
int Interval::next_usage(IntervalUseKind min_use_kind, int from) const {
assert(LinearScan::is_virtual_interval(this), "cannot access use positions for fixed intervals");
for (int i = _use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
if (_use_pos_and_kinds.at(i) >= from && _use_pos_and_kinds.at(i + 1) >= min_use_kind) {
return _use_pos_and_kinds.at(i);
}
}
return max_jint;
}
int Interval::next_usage_exact(IntervalUseKind exact_use_kind, int from) const {
assert(LinearScan::is_virtual_interval(this), "cannot access use positions for fixed intervals");
for (int i = _use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
if (_use_pos_and_kinds.at(i) >= from && _use_pos_and_kinds.at(i + 1) == exact_use_kind) {
return _use_pos_and_kinds.at(i);
}
}
return max_jint;
}
int Interval::previous_usage(IntervalUseKind min_use_kind, int from) const {
assert(LinearScan::is_virtual_interval(this), "cannot access use positions for fixed intervals");
int prev = 0;
for (int i = _use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
if (_use_pos_and_kinds.at(i) > from) {
return prev;
}
if (_use_pos_and_kinds.at(i + 1) >= min_use_kind) {
prev = _use_pos_and_kinds.at(i);
}
}
return prev;
}
void Interval::add_use_pos(int pos, IntervalUseKind use_kind) {
assert(covers(pos, LIR_OpVisitState::inputMode), "use position not covered by live range");
// do not add use positions for precolored intervals because
// they are never used
if (use_kind != noUse && reg_num() >= LIR_OprDesc::vreg_base) {
#ifdef ASSERT
assert(_use_pos_and_kinds.length() % 2 == 0, "must be");
for (int i = 0; i < _use_pos_and_kinds.length(); i += 2) {
assert(pos <= _use_pos_and_kinds.at(i), "already added a use-position with lower position");
assert(_use_pos_and_kinds.at(i + 1) >= firstValidKind && _use_pos_and_kinds.at(i + 1) <= lastValidKind, "invalid use kind");
if (i > 0) {
assert(_use_pos_and_kinds.at(i) < _use_pos_and_kinds.at(i - 2), "not sorted descending");
}
}
#endif
// Note: add_use is called in descending order, so list gets sorted
// automatically by just appending new use positions
int len = _use_pos_and_kinds.length();
if (len == 0 || _use_pos_and_kinds.at(len - 2) > pos) {
_use_pos_and_kinds.append(pos);
_use_pos_and_kinds.append(use_kind);
} else if (_use_pos_and_kinds.at(len - 1) < use_kind) {
assert(_use_pos_and_kinds.at(len - 2) == pos, "list not sorted correctly");
_use_pos_and_kinds.at_put(len - 1, use_kind);
}
}
}
void Interval::add_range(int from, int to) {
assert(from < to, "invalid range");
assert(first() == Range::end() || to < first()->next()->from(), "not inserting at begin of interval");
assert(from <= first()->to(), "not inserting at begin of interval");
if (first()->from() <= to) {
// join intersecting ranges
first()->set_from(MIN2(from, first()->from()));
first()->set_to (MAX2(to, first()->to()));
} else {
// insert new range
_first = new Range(from, to, first());
}
}
Interval* Interval::new_split_child() {
// allocate new interval
Interval* result = new Interval(-1);
result->set_type(type());
Interval* parent = split_parent();
result->_split_parent = parent;
result->set_register_hint(parent);
// insert new interval in children-list of parent
if (parent->_split_children.length() == 0) {
assert(is_split_parent(), "list must be initialized at first split");
parent->_split_children = IntervalList(4);
parent->_split_children.append(this);
}
parent->_split_children.append(result);
return result;
}
// split this interval at the specified position and return
// the remainder as a new interval.
//
// when an interval is split, a bi-directional link is established between the original interval
// (the split parent) and the intervals that are split off this interval (the split children)
// When a split child is split again, the new created interval is also a direct child
// of the original parent (there is no tree of split children stored, but a flat list)
// All split children are spilled to the same stack slot (stored in _canonical_spill_slot)
//
// Note: The new interval has no valid reg_num
Interval* Interval::split(int split_pos) {
assert(LinearScan::is_virtual_interval(this), "cannot split fixed intervals");
// allocate new interval
Interval* result = new_split_child();
// split the ranges
Range* prev = NULL;
Range* cur = _first;
while (cur != Range::end() && cur->to() <= split_pos) {
prev = cur;
cur = cur->next();
}
assert(cur != Range::end(), "split interval after end of last range");
if (cur->from() < split_pos) {
result->_first = new Range(split_pos, cur->to(), cur->next());
cur->set_to(split_pos);
cur->set_next(Range::end());
} else {
assert(prev != NULL, "split before start of first range");
result->_first = cur;
prev->set_next(Range::end());
}
result->_current = result->_first;
_cached_to = -1; // clear cached value
// split list of use positions
int total_len = _use_pos_and_kinds.length();
int start_idx = total_len - 2;
while (start_idx >= 0 && _use_pos_and_kinds.at(start_idx) < split_pos) {
start_idx -= 2;
}
intStack new_use_pos_and_kinds(total_len - start_idx);
int i;
for (i = start_idx + 2; i < total_len; i++) {
new_use_pos_and_kinds.append(_use_pos_and_kinds.at(i));
}
_use_pos_and_kinds.truncate(start_idx + 2);
result->_use_pos_and_kinds = _use_pos_and_kinds;
_use_pos_and_kinds = new_use_pos_and_kinds;
#ifdef ASSERT
assert(_use_pos_and_kinds.length() % 2 == 0, "must have use kind for each use pos");
assert(result->_use_pos_and_kinds.length() % 2 == 0, "must have use kind for each use pos");
assert(_use_pos_and_kinds.length() + result->_use_pos_and_kinds.length() == total_len, "missed some entries");
for (i = 0; i < _use_pos_and_kinds.length(); i += 2) {
assert(_use_pos_and_kinds.at(i) < split_pos, "must be");
assert(_use_pos_and_kinds.at(i + 1) >= firstValidKind && _use_pos_and_kinds.at(i + 1) <= lastValidKind, "invalid use kind");
}
for (i = 0; i < result->_use_pos_and_kinds.length(); i += 2) {
assert(result->_use_pos_and_kinds.at(i) >= split_pos, "must be");
assert(result->_use_pos_and_kinds.at(i + 1) >= firstValidKind && result->_use_pos_and_kinds.at(i + 1) <= lastValidKind, "invalid use kind");
}
#endif
return result;
}
// split this interval at the specified position and return
// the head as a new interval (the original interval is the tail)
//
// Currently, only the first range can be split, and the new interval
// must not have split positions
Interval* Interval::split_from_start(int split_pos) {
assert(LinearScan::is_virtual_interval(this), "cannot split fixed intervals");
assert(split_pos > from() && split_pos < to(), "can only split inside interval");
assert(split_pos > _first->from() && split_pos <= _first->to(), "can only split inside first range");
assert(first_usage(noUse) > split_pos, "can not split when use positions are present");
// allocate new interval
Interval* result = new_split_child();
// the new created interval has only one range (checked by assertion above),
// so the splitting of the ranges is very simple
result->add_range(_first->from(), split_pos);
if (split_pos == _first->to()) {
assert(_first->next() != Range::end(), "must not be at end");
_first = _first->next();
} else {
_first->set_from(split_pos);
}
return result;
}
// returns true if the op_id is inside the interval
bool Interval::covers(int op_id, LIR_OpVisitState::OprMode mode) const {
Range* cur = _first;
while (cur != Range::end() && cur->to() < op_id) {
cur = cur->next();
}
if (cur != Range::end()) {
assert(cur->to() != cur->next()->from(), "ranges not separated");
if (mode == LIR_OpVisitState::outputMode) {
return cur->from() <= op_id && op_id < cur->to();
} else {
return cur->from() <= op_id && op_id <= cur->to();
}
}
return false;
}
// returns true if the interval has any hole between hole_from and hole_to
// (even if the hole has only the length 1)
bool Interval::has_hole_between(int hole_from, int hole_to) {
assert(hole_from < hole_to, "check");
assert(from() <= hole_from && hole_to <= to(), "index out of interval");
Range* cur = _first;
while (cur != Range::end()) {
assert(cur->to() < cur->next()->from(), "no space between ranges");
// hole-range starts before this range -> hole
if (hole_from < cur->from()) {
return true;
// hole-range completely inside this range -> no hole
} else if (hole_to <= cur->to()) {
return false;
// overlapping of hole-range with this range -> hole
} else if (hole_from <= cur->to()) {
return true;
}
cur = cur->next();
}
return false;
}
#ifndef PRODUCT
void Interval::print(outputStream* out) const {
const char* SpillState2Name[] = { "no definition", "no spill store", "one spill store", "store at definition", "start in memory", "no optimization" };
const char* UseKind2Name[] = { "N", "L", "S", "M" };
const char* type_name;
LIR_Opr opr = LIR_OprFact::illegal();
if (reg_num() < LIR_OprDesc::vreg_base) {
type_name = "fixed";
// need a temporary operand for fixed intervals because type() cannot be called
if (assigned_reg() >= pd_first_cpu_reg && assigned_reg() <= pd_last_cpu_reg) {
opr = LIR_OprFact::single_cpu(assigned_reg());
} else if (assigned_reg() >= pd_first_fpu_reg && assigned_reg() <= pd_last_fpu_reg) {
opr = LIR_OprFact::single_fpu(assigned_reg() - pd_first_fpu_reg);
#ifdef X86
} else if (assigned_reg() >= pd_first_xmm_reg && assigned_reg() <= pd_last_xmm_reg) {
opr = LIR_OprFact::single_xmm(assigned_reg() - pd_first_xmm_reg);
#endif
} else {
ShouldNotReachHere();
}
} else {
type_name = type2name(type());
if (assigned_reg() != -1 &&
(LinearScan::num_physical_regs(type()) == 1 || assigned_regHi() != -1)) {
opr = LinearScan::calc_operand_for_interval(this);
}
}
out->print("%d %s ", reg_num(), type_name);
if (opr->is_valid()) {
out->print("\"");
opr->print(out);
out->print("\" ");
}
out->print("%d %d ", split_parent()->reg_num(), (register_hint(false) != NULL ? register_hint(false)->reg_num() : -1));
// print ranges
Range* cur = _first;
while (cur != Range::end()) {
cur->print(out);
cur = cur->next();
assert(cur != NULL, "range list not closed with range sentinel");
}
// print use positions
int prev = 0;
assert(_use_pos_and_kinds.length() % 2 == 0, "must be");
for (int i =_use_pos_and_kinds.length() - 2; i >= 0; i -= 2) {
assert(_use_pos_and_kinds.at(i + 1) >= firstValidKind && _use_pos_and_kinds.at(i + 1) <= lastValidKind, "invalid use kind");
assert(prev < _use_pos_and_kinds.at(i), "use positions not sorted");
out->print("%d %s ", _use_pos_and_kinds.at(i), UseKind2Name[_use_pos_and_kinds.at(i + 1)]);
prev = _use_pos_and_kinds.at(i);
}
out->print(" \"%s\"", SpillState2Name[spill_state()]);
out->cr();
}
#endif
// **** Implementation of IntervalWalker ****************************
IntervalWalker::IntervalWalker(LinearScan* allocator, Interval* unhandled_fixed_first, Interval* unhandled_any_first)
: _compilation(allocator->compilation())
, _allocator(allocator)
{
_unhandled_first[fixedKind] = unhandled_fixed_first;
_unhandled_first[anyKind] = unhandled_any_first;
_active_first[fixedKind] = Interval::end();
_inactive_first[fixedKind] = Interval::end();
_active_first[anyKind] = Interval::end();
_inactive_first[anyKind] = Interval::end();
_current_position = -1;
_current = NULL;
next_interval();
}
// append interval at top of list
void IntervalWalker::append_unsorted(Interval** list, Interval* interval) {
interval->set_next(*list); *list = interval;
}
// append interval in order of current range from()
void IntervalWalker::append_sorted(Interval** list, Interval* interval) {
Interval* prev = NULL;
Interval* cur = *list;
while (cur->current_from() < interval->current_from()) {
prev = cur; cur = cur->next();
}
if (prev == NULL) {
*list = interval;
} else {
prev->set_next(interval);
}
interval->set_next(cur);
}
void IntervalWalker::append_to_unhandled(Interval** list, Interval* interval) {
assert(interval->from() >= current()->current_from(), "cannot append new interval before current walk position");
Interval* prev = NULL;
Interval* cur = *list;
while (cur->from() < interval->from() || (cur->from() == interval->from() && cur->first_usage(noUse) < interval->first_usage(noUse))) {
prev = cur; cur = cur->next();
}
if (prev == NULL) {
*list = interval;
} else {
prev->set_next(interval);
}
interval->set_next(cur);
}
inline bool IntervalWalker::remove_from_list(Interval** list, Interval* i) {
while (*list != Interval::end() && *list != i) {
list = (*list)->next_addr();
}
if (*list != Interval::end()) {
assert(*list == i, "check");
*list = (*list)->next();
return true;
} else {
return false;
}
}
void IntervalWalker::remove_from_list(Interval* i) {
bool deleted;
if (i->state() == activeState) {
deleted = remove_from_list(active_first_addr(anyKind), i);
} else {
assert(i->state() == inactiveState, "invalid state");
deleted = remove_from_list(inactive_first_addr(anyKind), i);
}
assert(deleted, "interval has not been found in list");
}
void IntervalWalker::walk_to(IntervalState state, int from) {
assert (state == activeState || state == inactiveState, "wrong state");
for_each_interval_kind(kind) {
Interval** prev = state == activeState ? active_first_addr(kind) : inactive_first_addr(kind);
Interval* next = *prev;
while (next->current_from() <= from) {
Interval* cur = next;
next = cur->next();
bool range_has_changed = false;
while (cur->current_to() <= from) {
cur->next_range();
range_has_changed = true;
}
// also handle move from inactive list to active list
range_has_changed = range_has_changed || (state == inactiveState && cur->current_from() <= from);
if (range_has_changed) {
// remove cur from list
*prev = next;
if (cur->current_at_end()) {
// move to handled state (not maintained as a list)
cur->set_state(handledState);
interval_moved(cur, kind, state, handledState);
} else if (cur->current_from() <= from){
// sort into active list
append_sorted(active_first_addr(kind), cur);
cur->set_state(activeState);
if (*prev == cur) {
assert(state == activeState, "check");
prev = cur->next_addr();
}
interval_moved(cur, kind, state, activeState);
} else {
// sort into inactive list
append_sorted(inactive_first_addr(kind), cur);
cur->set_state(inactiveState);
if (*prev == cur) {
assert(state == inactiveState, "check");
prev = cur->next_addr();
}
interval_moved(cur, kind, state, inactiveState);
}
} else {
prev = cur->next_addr();
continue;
}
}
}
}
void IntervalWalker::next_interval() {
IntervalKind kind;
Interval* any = _unhandled_first[anyKind];
Interval* fixed = _unhandled_first[fixedKind];
if (any != Interval::end()) {
// intervals may start at same position -> prefer fixed interval
kind = fixed != Interval::end() && fixed->from() <= any->from() ? fixedKind : anyKind;
assert (kind == fixedKind && fixed->from() <= any->from() ||
kind == anyKind && any->from() <= fixed->from(), "wrong interval!!!");
assert(any == Interval::end() || fixed == Interval::end() || any->from() != fixed->from() || kind == fixedKind, "if fixed and any-Interval start at same position, fixed must be processed first");
} else if (fixed != Interval::end()) {
kind = fixedKind;
} else {
_current = NULL; return;
}
_current_kind = kind;
_current = _unhandled_first[kind];
_unhandled_first[kind] = _current->next();
_current->set_next(Interval::end());
_current->rewind_range();
}
void IntervalWalker::walk_to(int lir_op_id) {
assert(_current_position <= lir_op_id, "can not walk backwards");
while (current() != NULL) {
bool is_active = current()->from() <= lir_op_id;
int id = is_active ? current()->from() : lir_op_id;
TRACE_LINEAR_SCAN(2, if (_current_position < id) { tty->cr(); tty->print_cr("walk_to(%d) **************************************************************", id); })
// set _current_position prior to call of walk_to
_current_position = id;
// call walk_to even if _current_position == id
walk_to(activeState, id);
walk_to(inactiveState, id);
if (is_active) {
current()->set_state(activeState);
if (activate_current()) {
append_sorted(active_first_addr(current_kind()), current());
interval_moved(current(), current_kind(), unhandledState, activeState);
}
next_interval();
} else {
return;
}
}
}
void IntervalWalker::interval_moved(Interval* interval, IntervalKind kind, IntervalState from, IntervalState to) {
#ifndef PRODUCT
if (TraceLinearScanLevel >= 4) {
#define print_state(state) \
switch(state) {\
case unhandledState: tty->print("unhandled"); break;\
case activeState: tty->print("active"); break;\
case inactiveState: tty->print("inactive"); break;\
case handledState: tty->print("handled"); break;\
default: ShouldNotReachHere(); \
}
print_state(from); tty->print(" to "); print_state(to);
tty->fill_to(23);
interval->print();
#undef print_state
}
#endif
}
// **** Implementation of LinearScanWalker **************************
LinearScanWalker::LinearScanWalker(LinearScan* allocator, Interval* unhandled_fixed_first, Interval* unhandled_any_first)
: IntervalWalker(allocator, unhandled_fixed_first, unhandled_any_first)
, _move_resolver(allocator)
{
for (int i = 0; i < LinearScan::nof_regs; i++) {
_spill_intervals[i] = new IntervalList(2);
}
}
inline void LinearScanWalker::init_use_lists(bool only_process_use_pos) {
for (int i = _first_reg; i <= _last_reg; i++) {
_use_pos[i] = max_jint;
if (!only_process_use_pos) {
_block_pos[i] = max_jint;
_spill_intervals[i]->clear();
}
}
}
inline void LinearScanWalker::exclude_from_use(int reg) {
assert(reg < LinearScan::nof_regs, "interval must have a register assigned (stack slots not allowed)");
if (reg >= _first_reg && reg <= _last_reg) {
_use_pos[reg] = 0;
}
}
inline void LinearScanWalker::exclude_from_use(Interval* i) {
assert(i->assigned_reg() != any_reg, "interval has no register assigned");
exclude_from_use(i->assigned_reg());
exclude_from_use(i->assigned_regHi());
}
inline void LinearScanWalker::set_use_pos(int reg, Interval* i, int use_pos, bool only_process_use_pos) {
assert(use_pos != 0, "must use exclude_from_use to set use_pos to 0");
if (reg >= _first_reg && reg <= _last_reg) {
if (_use_pos[reg] > use_pos) {
_use_pos[reg] = use_pos;
}
if (!only_process_use_pos) {
_spill_intervals[reg]->append(i);
}
}
}
inline void LinearScanWalker::set_use_pos(Interval* i, int use_pos, bool only_process_use_pos) {
assert(i->assigned_reg() != any_reg, "interval has no register assigned");
if (use_pos != -1) {
set_use_pos(i->assigned_reg(), i, use_pos, only_process_use_pos);
set_use_pos(i->assigned_regHi(), i, use_pos, only_process_use_pos);
}
}
inline void LinearScanWalker::set_block_pos(int reg, Interval* i, int block_pos) {
if (reg >= _first_reg && reg <= _last_reg) {
if (_block_pos[reg] > block_pos) {
_block_pos[reg] = block_pos;
}
if (_use_pos[reg] > block_pos) {
_use_pos[reg] = block_pos;
}
}
}
inline void LinearScanWalker::set_block_pos(Interval* i, int block_pos) {
assert(i->assigned_reg() != any_reg, "interval has no register assigned");
if (block_pos != -1) {
set_block_pos(i->assigned_reg(), i, block_pos);
set_block_pos(i->assigned_regHi(), i, block_pos);
}
}
void LinearScanWalker::free_exclude_active_fixed() {
Interval* list = active_first(fixedKind);
while (list != Interval::end()) {
assert(list->assigned_reg() < LinearScan::nof_regs, "active interval must have a register assigned");
exclude_from_use(list);
list = list->next();
}
}
void LinearScanWalker::free_exclude_active_any() {
Interval* list = active_first(anyKind);
while (list != Interval::end()) {
exclude_from_use(list);
list = list->next();
}
}
void LinearScanWalker::free_collect_inactive_fixed(Interval* cur) {
Interval* list = inactive_first(fixedKind);
while (list != Interval::end()) {
if (cur->to() <= list->current_from()) {
assert(list->current_intersects_at(cur) == -1, "must not intersect");
set_use_pos(list, list->current_from(), true);
} else {
set_use_pos(list, list->current_intersects_at(cur), true);
}
list = list->next();
}
}
void LinearScanWalker::free_collect_inactive_any(Interval* cur) {
Interval* list = inactive_first(anyKind);
while (list != Interval::end()) {
set_use_pos(list, list->current_intersects_at(cur), true);
list = list->next();
}
}
void LinearScanWalker::free_collect_unhandled(IntervalKind kind, Interval* cur) {
Interval* list = unhandled_first(kind);
while (list != Interval::end()) {
set_use_pos(list, list->intersects_at(cur), true);
if (kind == fixedKind && cur->to() <= list->from()) {
set_use_pos(list, list->from(), true);
}
list = list->next();
}
}
void LinearScanWalker::spill_exclude_active_fixed() {
Interval* list = active_first(fixedKind);
while (list != Interval::end()) {
exclude_from_use(list);
list = list->next();
}
}
void LinearScanWalker::spill_block_unhandled_fixed(Interval* cur) {
Interval* list = unhandled_first(fixedKind);
while (list != Interval::end()) {
set_block_pos(list, list->intersects_at(cur));
list = list->next();
}
}
void LinearScanWalker::spill_block_inactive_fixed(Interval* cur) {
Interval* list = inactive_first(fixedKind);
while (list != Interval::end()) {
if (cur->to() > list->current_from()) {
set_block_pos(list, list->current_intersects_at(cur));
} else {
assert(list->current_intersects_at(cur) == -1, "invalid optimization: intervals intersect");
}
list = list->next();
}
}
void LinearScanWalker::spill_collect_active_any() {
Interval* list = active_first(anyKind);
while (list != Interval::end()) {
set_use_pos(list, MIN2(list->next_usage(loopEndMarker, _current_position), list->to()), false);
list = list->next();
}
}
void LinearScanWalker::spill_collect_inactive_any(Interval* cur) {
Interval* list = inactive_first(anyKind);
while (list != Interval::end()) {
if (list->current_intersects(cur)) {
set_use_pos(list, MIN2(list->next_usage(loopEndMarker, _current_position), list->to()), false);
}
list = list->next();
}
}
void LinearScanWalker::insert_move(int op_id, Interval* src_it, Interval* dst_it) {
// output all moves here. When source and target are equal, the move is
// optimized away later in assign_reg_nums
op_id = (op_id + 1) & ~1;
BlockBegin* op_block = allocator()->block_of_op_with_id(op_id);
assert(op_id > 0 && allocator()->block_of_op_with_id(op_id - 2) == op_block, "cannot insert move at block boundary");
// calculate index of instruction inside instruction list of current block
// the minimal index (for a block with no spill moves) can be calculated because the
// numbering of instructions is known.
// When the block already contains spill moves, the index must be increased until the
// correct index is reached.
LIR_OpList* list = op_block->lir()->instructions_list();
int index = (op_id - list->at(0)->id()) / 2;
assert(list->at(index)->id() <= op_id, "error in calculation");
while (list->at(index)->id() != op_id) {
index++;
assert(0 <= index && index < list->length(), "index out of bounds");
}
assert(1 <= index && index < list->length(), "index out of bounds");
assert(list->at(index)->id() == op_id, "error in calculation");
// insert new instruction before instruction at position index
_move_resolver.move_insert_position(op_block->lir(), index - 1);
_move_resolver.add_mapping(src_it, dst_it);
}
int LinearScanWalker::find_optimal_split_pos(BlockBegin* min_block, BlockBegin* max_block, int max_split_pos) {
int from_block_nr = min_block->linear_scan_number();
int to_block_nr = max_block->linear_scan_number();
assert(0 <= from_block_nr && from_block_nr < block_count(), "out of range");
assert(0 <= to_block_nr && to_block_nr < block_count(), "out of range");
assert(from_block_nr < to_block_nr, "must cross block boundary");
// Try to split at end of max_block. If this would be after
// max_split_pos, then use the begin of max_block
int optimal_split_pos = max_block->last_lir_instruction_id() + 2;
if (optimal_split_pos > max_split_pos) {
optimal_split_pos = max_block->first_lir_instruction_id();
}
int min_loop_depth = max_block->loop_depth();
for (int i = to_block_nr - 1; i >= from_block_nr; i--) {
BlockBegin* cur = block_at(i);
if (cur->loop_depth() < min_loop_depth) {
// block with lower loop-depth found -> split at the end of this block
min_loop_depth = cur->loop_depth();
optimal_split_pos = cur->last_lir_instruction_id() + 2;
}
}
assert(optimal_split_pos > allocator()->max_lir_op_id() || allocator()->is_block_begin(optimal_split_pos), "algorithm must move split pos to block boundary");
return optimal_split_pos;
}
int LinearScanWalker::find_optimal_split_pos(Interval* it, int min_split_pos, int max_split_pos, bool do_loop_optimization) {
int optimal_split_pos = -1;
if (min_split_pos == max_split_pos) {
// trivial case, no optimization of split position possible
TRACE_LINEAR_SCAN(4, tty->print_cr(" min-pos and max-pos are equal, no optimization possible"));
optimal_split_pos = min_split_pos;
} else {
assert(min_split_pos < max_split_pos, "must be true then");
assert(min_split_pos > 0, "cannot access min_split_pos - 1 otherwise");
// reason for using min_split_pos - 1: when the minimal split pos is exactly at the
// beginning of a block, then min_split_pos is also a possible split position.
// Use the block before as min_block, because then min_block->last_lir_instruction_id() + 2 == min_split_pos
BlockBegin* min_block = allocator()->block_of_op_with_id(min_split_pos - 1);
// reason for using max_split_pos - 1: otherwise there would be an assertion failure
// when an interval ends at the end of the last block of the method
// (in this case, max_split_pos == allocator()->max_lir_op_id() + 2, and there is no
// block at this op_id)
BlockBegin* max_block = allocator()->block_of_op_with_id(max_split_pos - 1);
assert(min_block->linear_scan_number() <= max_block->linear_scan_number(), "invalid order");
if (min_block == max_block) {
// split position cannot be moved to block boundary, so split as late as possible
TRACE_LINEAR_SCAN(4, tty->print_cr(" cannot move split pos to block boundary because min_pos and max_pos are in same block"));
optimal_split_pos = max_split_pos;
} else if (it->has_hole_between(max_split_pos - 1, max_split_pos) && !allocator()->is_block_begin(max_split_pos)) {
// Do not move split position if the interval has a hole before max_split_pos.
// Intervals resulting from Phi-Functions have more than one definition (marked
// as mustHaveRegister) with a hole before each definition. When the register is needed
// for the second definition, an earlier reloading is unnecessary.
TRACE_LINEAR_SCAN(4, tty->print_cr(" interval has hole just before max_split_pos, so splitting at max_split_pos"));
optimal_split_pos = max_split_pos;
} else {
// seach optimal block boundary between min_split_pos and max_split_pos
TRACE_LINEAR_SCAN(4, tty->print_cr(" moving split pos to optimal block boundary between block B%d and B%d", min_block->block_id(), max_block->block_id()));
if (do_loop_optimization) {
// Loop optimization: if a loop-end marker is found between min- and max-position,
// then split before this loop
int loop_end_pos = it->next_usage_exact(loopEndMarker, min_block->last_lir_instruction_id() + 2);
TRACE_LINEAR_SCAN(4, tty->print_cr(" loop optimization: loop end found at pos %d", loop_end_pos));
assert(loop_end_pos > min_split_pos, "invalid order");
if (loop_end_pos < max_split_pos) {
// loop-end marker found between min- and max-position
// if it is not the end marker for the same loop as the min-position, then move
// the max-position to this loop block.
// Desired result: uses tagged as shouldHaveRegister inside a loop cause a reloading
// of the interval (normally, only mustHaveRegister causes a reloading)
BlockBegin* loop_block = allocator()->block_of_op_with_id(loop_end_pos);
TRACE_LINEAR_SCAN(4, tty->print_cr(" interval is used in loop that ends in block B%d, so trying to move max_block back from B%d to B%d", loop_block->block_id(), max_block->block_id(), loop_block->block_id()));
assert(loop_block != min_block, "loop_block and min_block must be different because block boundary is needed between");
optimal_split_pos = find_optimal_split_pos(min_block, loop_block, loop_block->last_lir_instruction_id() + 2);
if (optimal_split_pos == loop_block->last_lir_instruction_id() + 2) {
optimal_split_pos = -1;
TRACE_LINEAR_SCAN(4, tty->print_cr(" loop optimization not necessary"));
} else {
TRACE_LINEAR_SCAN(4, tty->print_cr(" loop optimization successful"));
}
}
}
if (optimal_split_pos == -1) {
// not calculated by loop optimization
optimal_split_pos = find_optimal_split_pos(min_block, max_block, max_split_pos);
}
}
}
TRACE_LINEAR_SCAN(4, tty->print_cr(" optimal split position: %d", optimal_split_pos));
return optimal_split_pos;
}
/*
split an interval at the optimal position between min_split_pos and
max_split_pos in two parts:
1) the left part has already a location assigned
2) the right part is sorted into to the unhandled-list
*/
void LinearScanWalker::split_before_usage(Interval* it, int min_split_pos, int max_split_pos) {
TRACE_LINEAR_SCAN(2, tty->print ("----- splitting interval: "); it->print());
TRACE_LINEAR_SCAN(2, tty->print_cr(" between %d and %d", min_split_pos, max_split_pos));
assert(it->from() < min_split_pos, "cannot split at start of interval");
assert(current_position() < min_split_pos, "cannot split before current position");
assert(min_split_pos <= max_split_pos, "invalid order");
assert(max_split_pos <= it->to(), "cannot split after end of interval");
int optimal_split_pos = find_optimal_split_pos(it, min_split_pos, max_split_pos, true);
assert(min_split_pos <= optimal_split_pos && optimal_split_pos <= max_split_pos, "out of range");
assert(optimal_split_pos <= it->to(), "cannot split after end of interval");
assert(optimal_split_pos > it->from(), "cannot split at start of interval");
if (optimal_split_pos == it->to() && it->next_usage(mustHaveRegister, min_split_pos) == max_jint) {
// the split position would be just before the end of the interval
// -> no split at all necessary
TRACE_LINEAR_SCAN(4, tty->print_cr(" no split necessary because optimal split position is at end of interval"));
return;
}
// must calculate this before the actual split is performed and before split position is moved to odd op_id
bool move_necessary = !allocator()->is_block_begin(optimal_split_pos) && !it->has_hole_between(optimal_split_pos - 1, optimal_split_pos);
if (!allocator()->is_block_begin(optimal_split_pos)) {
// move position before actual instruction (odd op_id)
optimal_split_pos = (optimal_split_pos - 1) | 1;
}
TRACE_LINEAR_SCAN(4, tty->print_cr(" splitting at position %d", optimal_split_pos));
assert(allocator()->is_block_begin(optimal_split_pos) || (optimal_split_pos % 2 == 1), "split pos must be odd when not on block boundary");
assert(!allocator()->is_block_begin(optimal_split_pos) || (optimal_split_pos % 2 == 0), "split pos must be even on block boundary");
Interval* split_part = it->split(optimal_split_pos);
allocator()->append_interval(split_part);
allocator()->copy_register_flags(it, split_part);
split_part->set_insert_move_when_activated(move_necessary);
append_to_unhandled(unhandled_first_addr(anyKind), split_part);
TRACE_LINEAR_SCAN(2, tty->print_cr(" split interval in two parts (insert_move_when_activated: %d)", move_necessary));
TRACE_LINEAR_SCAN(2, tty->print (" "); it->print());
TRACE_LINEAR_SCAN(2, tty->print (" "); split_part->print());
}
/*
split an interval at the optimal position between min_split_pos and
max_split_pos in two parts:
1) the left part has already a location assigned
2) the right part is always on the stack and therefore ignored in further processing
*/
void LinearScanWalker::split_for_spilling(Interval* it) {
// calculate allowed range of splitting position
int max_split_pos = current_position();
int min_split_pos = MAX2(it->previous_usage(shouldHaveRegister, max_split_pos) + 1, it->from());
TRACE_LINEAR_SCAN(2, tty->print ("----- splitting and spilling interval: "); it->print());
TRACE_LINEAR_SCAN(2, tty->print_cr(" between %d and %d", min_split_pos, max_split_pos));
assert(it->state() == activeState, "why spill interval that is not active?");
assert(it->from() <= min_split_pos, "cannot split before start of interval");
assert(min_split_pos <= max_split_pos, "invalid order");
assert(max_split_pos < it->to(), "cannot split at end end of interval");
assert(current_position() < it->to(), "interval must not end before current position");
if (min_split_pos == it->from()) {
// the whole interval is never used, so spill it entirely to memory
TRACE_LINEAR_SCAN(2, tty->print_cr(" spilling entire interval because split pos is at beginning of interval"));
assert(it->first_usage(shouldHaveRegister) > current_position(), "interval must not have use position before current_position");
allocator()->assign_spill_slot(it);
allocator()->change_spill_state(it, min_split_pos);
// Also kick parent intervals out of register to memory when they have no use
// position. This avoids short interval in register surrounded by intervals in
// memory -> avoid useless moves from memory to register and back
Interval* parent = it;
while (parent != NULL && parent->is_split_child()) {
parent = parent->split_child_before_op_id(parent->from());
if (parent->assigned_reg() < LinearScan::nof_regs) {
if (parent->first_usage(shouldHaveRegister) == max_jint) {
// parent is never used, so kick it out of its assigned register
TRACE_LINEAR_SCAN(4, tty->print_cr(" kicking out interval %d out of its register because it is never used", parent->reg_num()));
allocator()->assign_spill_slot(parent);
} else {
// do not go further back because the register is actually used by the interval
parent = NULL;
}
}
}
} else {
// search optimal split pos, split interval and spill only the right hand part
int optimal_split_pos = find_optimal_split_pos(it, min_split_pos, max_split_pos, false);
assert(min_split_pos <= optimal_split_pos && optimal_split_pos <= max_split_pos, "out of range");
assert(optimal_split_pos < it->to(), "cannot split at end of interval");
assert(optimal_split_pos >= it->from(), "cannot split before start of interval");
if (!allocator()->is_block_begin(optimal_split_pos)) {
// move position before actual instruction (odd op_id)
optimal_split_pos = (optimal_split_pos - 1) | 1;
}
TRACE_LINEAR_SCAN(4, tty->print_cr(" splitting at position %d", optimal_split_pos));
assert(allocator()->is_block_begin(optimal_split_pos) || (optimal_split_pos % 2 == 1), "split pos must be odd when not on block boundary");
assert(!allocator()->is_block_begin(optimal_split_pos) || (optimal_split_pos % 2 == 0), "split pos must be even on block boundary");
Interval* spilled_part = it->split(optimal_split_pos);
allocator()->append_interval(spilled_part);
allocator()->assign_spill_slot(spilled_part);
allocator()->change_spill_state(spilled_part, optimal_split_pos);
if (!allocator()->is_block_begin(optimal_split_pos)) {
TRACE_LINEAR_SCAN(4, tty->print_cr(" inserting move from interval %d to %d", it->reg_num(), spilled_part->reg_num()));
insert_move(optimal_split_pos, it, spilled_part);
}
// the current_split_child is needed later when moves are inserted for reloading
assert(spilled_part->current_split_child() == it, "overwriting wrong current_split_child");
spilled_part->make_current_split_child();
TRACE_LINEAR_SCAN(2, tty->print_cr(" split interval in two parts"));
TRACE_LINEAR_SCAN(2, tty->print (" "); it->print());
TRACE_LINEAR_SCAN(2, tty->print (" "); spilled_part->print());
}
}
void LinearScanWalker::split_stack_interval(Interval* it) {
int min_split_pos = current_position() + 1;
int max_split_pos = MIN2(it->first_usage(shouldHaveRegister), it->to());
split_before_usage(it, min_split_pos, max_split_pos);
}
void LinearScanWalker::split_when_partial_register_available(Interval* it, int register_available_until) {
int min_split_pos = MAX2(it->previous_usage(shouldHaveRegister, register_available_until), it->from() + 1);
int max_split_pos = register_available_until;
split_before_usage(it, min_split_pos, max_split_pos);
}
void LinearScanWalker::split_and_spill_interval(Interval* it) {
assert(it->state() == activeState || it->state() == inactiveState, "other states not allowed");
int current_pos = current_position();
if (it->state() == inactiveState) {
// the interval is currently inactive, so no spill slot is needed for now.
// when the split part is activated, the interval has a new chance to get a register,
// so in the best case no stack slot is necessary
assert(it->has_hole_between(current_pos - 1, current_pos + 1), "interval can not be inactive otherwise");
split_before_usage(it, current_pos + 1, current_pos + 1);
} else {
// search the position where the interval must have a register and split
// at the optimal position before.
// The new created part is added to the unhandled list and will get a register
// when it is activated
int min_split_pos = current_pos + 1;
int max_split_pos = MIN2(it->next_usage(mustHaveRegister, min_split_pos), it->to());
split_before_usage(it, min_split_pos, max_split_pos);
assert(it->next_usage(mustHaveRegister, current_pos) == max_jint, "the remaining part is spilled to stack and therefore has no register");
split_for_spilling(it);
}
}
int LinearScanWalker::find_free_reg(int reg_needed_until, int interval_to, int hint_reg, int ignore_reg, bool* need_split) {
int min_full_reg = any_reg;
int max_partial_reg = any_reg;
for (int i = _first_reg; i <= _last_reg; i++) {
if (i == ignore_reg) {
// this register must be ignored
} else if (_use_pos[i] >= interval_to) {
// this register is free for the full interval
if (min_full_reg == any_reg || i == hint_reg || (_use_pos[i] < _use_pos[min_full_reg] && min_full_reg != hint_reg)) {
min_full_reg = i;
}
} else if (_use_pos[i] > reg_needed_until) {
// this register is at least free until reg_needed_until
if (max_partial_reg == any_reg || i == hint_reg || (_use_pos[i] > _use_pos[max_partial_reg] && max_partial_reg != hint_reg)) {
max_partial_reg = i;
}
}
}
if (min_full_reg != any_reg) {
return min_full_reg;
} else if (max_partial_reg != any_reg) {
*need_split = true;
return max_partial_reg;
} else {
return any_reg;
}
}
int LinearScanWalker::find_free_double_reg(int reg_needed_until, int interval_to, int hint_reg, bool* need_split) {
assert((_last_reg - _first_reg + 1) % 2 == 0, "adjust algorithm");
int min_full_reg = any_reg;
int max_partial_reg = any_reg;
for (int i = _first_reg; i < _last_reg; i+=2) {
if (_use_pos[i] >= interval_to && _use_pos[i + 1] >= interval_to) {
// this register is free for the full interval
if (min_full_reg == any_reg || i == hint_reg || (_use_pos[i] < _use_pos[min_full_reg] && min_full_reg != hint_reg)) {
min_full_reg = i;
}
} else if (_use_pos[i] > reg_needed_until && _use_pos[i + 1] > reg_needed_until) {
// this register is at least free until reg_needed_until
if (max_partial_reg == any_reg || i == hint_reg || (_use_pos[i] > _use_pos[max_partial_reg] && max_partial_reg != hint_reg)) {
max_partial_reg = i;
}
}
}
if (min_full_reg != any_reg) {
return min_full_reg;
} else if (max_partial_reg != any_reg) {
*need_split = true;
return max_partial_reg;
} else {
return any_reg;
}
}
bool LinearScanWalker::alloc_free_reg(Interval* cur) {
TRACE_LINEAR_SCAN(2, tty->print("trying to find free register for "); cur->print());
init_use_lists(true);
free_exclude_active_fixed();
free_exclude_active_any();
free_collect_inactive_fixed(cur);
free_collect_inactive_any(cur);
// free_collect_unhandled(fixedKind, cur);
assert(unhandled_first(fixedKind) == Interval::end(), "must not have unhandled fixed intervals because all fixed intervals have a use at position 0");
// _use_pos contains the start of the next interval that has this register assigned
// (either as a fixed register or a normal allocated register in the past)
// only intervals overlapping with cur are processed, non-overlapping invervals can be ignored safely
TRACE_LINEAR_SCAN(4, tty->print_cr(" state of registers:"));
TRACE_LINEAR_SCAN(4, for (int i = _first_reg; i <= _last_reg; i++) tty->print_cr(" reg %d: use_pos: %d", i, _use_pos[i]));
int hint_reg, hint_regHi;
Interval* register_hint = cur->register_hint();
if (register_hint != NULL) {
hint_reg = register_hint->assigned_reg();
hint_regHi = register_hint->assigned_regHi();
if (allocator()->is_precolored_cpu_interval(register_hint)) {
assert(hint_reg != any_reg && hint_regHi == any_reg, "must be for fixed intervals");
hint_regHi = hint_reg + 1; // connect e.g. eax-edx
}
TRACE_LINEAR_SCAN(4, tty->print(" hint registers %d, %d from interval ", hint_reg, hint_regHi); register_hint->print());
} else {
hint_reg = any_reg;
hint_regHi = any_reg;
}
assert(hint_reg == any_reg || hint_reg != hint_regHi, "hint reg and regHi equal");
assert(cur->assigned_reg() == any_reg && cur->assigned_regHi() == any_reg, "register already assigned to interval");
// the register must be free at least until this position
int reg_needed_until = cur->from() + 1;
int interval_to = cur->to();
bool need_split = false;
int split_pos = -1;
int reg = any_reg;
int regHi = any_reg;
if (_adjacent_regs) {
reg = find_free_double_reg(reg_needed_until, interval_to, hint_reg, &need_split);
regHi = reg + 1;
if (reg == any_reg) {
return false;
}
split_pos = MIN2(_use_pos[reg], _use_pos[regHi]);
} else {
reg = find_free_reg(reg_needed_until, interval_to, hint_reg, any_reg, &need_split);
if (reg == any_reg) {
return false;
}
split_pos = _use_pos[reg];
if (_num_phys_regs == 2) {
regHi = find_free_reg(reg_needed_until, interval_to, hint_regHi, reg, &need_split);
if (_use_pos[reg] < interval_to && regHi == any_reg) {
// do not split interval if only one register can be assigned until the split pos
// (when one register is found for the whole interval, split&spill is only
// performed for the hi register)
return false;
} else if (regHi != any_reg) {
split_pos = MIN2(split_pos, _use_pos[regHi]);
// sort register numbers to prevent e.g. a move from eax,ebx to ebx,eax
if (reg > regHi) {
int temp = reg;
reg = regHi;
regHi = temp;
}
}
}
}
cur->assign_reg(reg, regHi);
TRACE_LINEAR_SCAN(2, tty->print_cr("selected register %d, %d", reg, regHi));
assert(split_pos > 0, "invalid split_pos");
if (need_split) {
// register not available for full interval, so split it
split_when_partial_register_available(cur, split_pos);
}
// only return true if interval is completely assigned
return _num_phys_regs == 1 || regHi != any_reg;
}
int LinearScanWalker::find_locked_reg(int reg_needed_until, int interval_to, int hint_reg, int ignore_reg, bool* need_split) {
int max_reg = any_reg;
for (int i = _first_reg; i <= _last_reg; i++) {
if (i == ignore_reg) {
// this register must be ignored
} else if (_use_pos[i] > reg_needed_until) {
if (max_reg == any_reg || i == hint_reg || (_use_pos[i] > _use_pos[max_reg] && max_reg != hint_reg)) {
max_reg = i;
}
}
}
if (max_reg != any_reg && _block_pos[max_reg] <= interval_to) {
*need_split = true;
}
return max_reg;
}
int LinearScanWalker::find_locked_double_reg(int reg_needed_until, int interval_to, int hint_reg, bool* need_split) {
assert((_last_reg - _first_reg + 1) % 2 == 0, "adjust algorithm");
int max_reg = any_reg;
for (int i = _first_reg; i < _last_reg; i+=2) {
if (_use_pos[i] > reg_needed_until && _use_pos[i + 1] > reg_needed_until) {
if (max_reg == any_reg || _use_pos[i] > _use_pos[max_reg]) {
max_reg = i;
}
}
}
if (_block_pos[max_reg] <= interval_to || _block_pos[max_reg + 1] <= interval_to) {
*need_split = true;
}
return max_reg;
}
void LinearScanWalker::split_and_spill_intersecting_intervals(int reg, int regHi) {
assert(reg != any_reg, "no register assigned");
for (int i = 0; i < _spill_intervals[reg]->length(); i++) {
Interval* it = _spill_intervals[reg]->at(i);
remove_from_list(it);
split_and_spill_interval(it);
}
if (regHi != any_reg) {
IntervalList* processed = _spill_intervals[reg];
for (int i = 0; i < _spill_intervals[regHi]->length(); i++) {
Interval* it = _spill_intervals[regHi]->at(i);
if (processed->index_of(it) == -1) {
remove_from_list(it);
split_and_spill_interval(it);
}
}
}
}
// Split an Interval and spill it to memory so that cur can be placed in a register
void LinearScanWalker::alloc_locked_reg(Interval* cur) {
TRACE_LINEAR_SCAN(2, tty->print("need to split and spill to get register for "); cur->print());
// collect current usage of registers
init_use_lists(false);
spill_exclude_active_fixed();
// spill_block_unhandled_fixed(cur);
assert(unhandled_first(fixedKind) == Interval::end(), "must not have unhandled fixed intervals because all fixed intervals have a use at position 0");
spill_block_inactive_fixed(cur);
spill_collect_active_any();
spill_collect_inactive_any(cur);
#ifndef PRODUCT
if (TraceLinearScanLevel >= 4) {
tty->print_cr(" state of registers:");
for (int i = _first_reg; i <= _last_reg; i++) {
tty->print(" reg %d: use_pos: %d, block_pos: %d, intervals: ", i, _use_pos[i], _block_pos[i]);
for (int j = 0; j < _spill_intervals[i]->length(); j++) {
tty->print("%d ", _spill_intervals[i]->at(j)->reg_num());
}
tty->cr();
}
}
#endif
// the register must be free at least until this position
int reg_needed_until = MIN2(cur->first_usage(mustHaveRegister), cur->from() + 1);
int interval_to = cur->to();
assert (reg_needed_until > 0 && reg_needed_until < max_jint, "interval has no use");
int split_pos = 0;
int use_pos = 0;
bool need_split = false;
int reg, regHi;
if (_adjacent_regs) {
reg = find_locked_double_reg(reg_needed_until, interval_to, any_reg, &need_split);
regHi = reg + 1;
if (reg != any_reg) {
use_pos = MIN2(_use_pos[reg], _use_pos[regHi]);
split_pos = MIN2(_block_pos[reg], _block_pos[regHi]);
}
} else {
reg = find_locked_reg(reg_needed_until, interval_to, any_reg, cur->assigned_reg(), &need_split);
regHi = any_reg;
if (reg != any_reg) {
use_pos = _use_pos[reg];
split_pos = _block_pos[reg];
if (_num_phys_regs == 2) {
if (cur->assigned_reg() != any_reg) {
regHi = reg;
reg = cur->assigned_reg();
} else {
regHi = find_locked_reg(reg_needed_until, interval_to, any_reg, reg, &need_split);
if (regHi != any_reg) {
use_pos = MIN2(use_pos, _use_pos[regHi]);
split_pos = MIN2(split_pos, _block_pos[regHi]);
}
}
if (regHi != any_reg && reg > regHi) {
// sort register numbers to prevent e.g. a move from eax,ebx to ebx,eax
int temp = reg;
reg = regHi;
regHi = temp;
}
}
}
}
if (reg == any_reg || (_num_phys_regs == 2 && regHi == any_reg) || use_pos <= cur->first_usage(mustHaveRegister)) {
// the first use of cur is later than the spilling position -> spill cur
TRACE_LINEAR_SCAN(4, tty->print_cr("able to spill current interval. first_usage(register): %d, use_pos: %d", cur->first_usage(mustHaveRegister), use_pos));
if (cur->first_usage(mustHaveRegister) <= cur->from() + 1) {
assert(false, "cannot spill interval that is used in first instruction (possible reason: no register found)");
// assign a reasonable register and do a bailout in product mode to avoid errors
allocator()->assign_spill_slot(cur);
BAILOUT("LinearScan: no register found");
}
split_and_spill_interval(cur);
} else {
TRACE_LINEAR_SCAN(4, tty->print_cr("decided to use register %d, %d", reg, regHi));
assert(reg != any_reg && (_num_phys_regs == 1 || regHi != any_reg), "no register found");
assert(split_pos > 0, "invalid split_pos");
assert(need_split == false || split_pos > cur->from(), "splitting interval at from");
cur->assign_reg(reg, regHi);
if (need_split) {
// register not available for full interval, so split it
split_when_partial_register_available(cur, split_pos);
}
// perform splitting and spilling for all affected intervalls
split_and_spill_intersecting_intervals(reg, regHi);
}
}
bool LinearScanWalker::no_allocation_possible(Interval* cur) {
#ifdef X86
// fast calculation of intervals that can never get a register because the
// the next instruction is a call that blocks all registers
// Note: this does not work if callee-saved registers are available (e.g. on Sparc)
// check if this interval is the result of a split operation
// (an interval got a register until this position)
int pos = cur->from();
if ((pos & 1) == 1) {
// the current instruction is a call that blocks all registers
if (pos < allocator()->max_lir_op_id() && allocator()->has_call(pos + 1)) {
TRACE_LINEAR_SCAN(4, tty->print_cr(" free register cannot be available because all registers blocked by following call"));
// safety check that there is really no register available
assert(alloc_free_reg(cur) == false, "found a register for this interval");
return true;
}
}
#endif
return false;
}
void LinearScanWalker::init_vars_for_alloc(Interval* cur) {
BasicType type = cur->type();
_num_phys_regs = LinearScan::num_physical_regs(type);
_adjacent_regs = LinearScan::requires_adjacent_regs(type);
if (pd_init_regs_for_alloc(cur)) {
// the appropriate register range was selected.
} else if (type == T_FLOAT || type == T_DOUBLE) {
_first_reg = pd_first_fpu_reg;
_last_reg = pd_last_fpu_reg;
} else {
_first_reg = pd_first_cpu_reg;
_last_reg = FrameMap::last_cpu_reg();
}
assert(0 <= _first_reg && _first_reg < LinearScan::nof_regs, "out of range");
assert(0 <= _last_reg && _last_reg < LinearScan::nof_regs, "out of range");
}
bool LinearScanWalker::is_move(LIR_Op* op, Interval* from, Interval* to) {
if (op->code() != lir_move) {
return false;
}
assert(op->as_Op1() != NULL, "move must be LIR_Op1");
LIR_Opr in = ((LIR_Op1*)op)->in_opr();
LIR_Opr res = ((LIR_Op1*)op)->result_opr();
return in->is_virtual() && res->is_virtual() && in->vreg_number() == from->reg_num() && res->vreg_number() == to->reg_num();
}
// optimization (especially for phi functions of nested loops):
// assign same spill slot to non-intersecting intervals
void LinearScanWalker::combine_spilled_intervals(Interval* cur) {
if (cur->is_split_child()) {
// optimization is only suitable for split parents
return;
}
Interval* register_hint = cur->register_hint(false);
if (register_hint == NULL) {
// cur is not the target of a move, otherwise register_hint would be set
return;
}
assert(register_hint->is_split_parent(), "register hint must be split parent");
if (cur->spill_state() != noOptimization || register_hint->spill_state() != noOptimization) {
// combining the stack slots for intervals where spill move optimization is applied
// is not benefitial and would cause problems
return;
}
int begin_pos = cur->from();
int end_pos = cur->to();
if (end_pos > allocator()->max_lir_op_id() || (begin_pos & 1) != 0 || (end_pos & 1) != 0) {
// safety check that lir_op_with_id is allowed
return;
}
if (!is_move(allocator()->lir_op_with_id(begin_pos), register_hint, cur) || !is_move(allocator()->lir_op_with_id(end_pos), cur, register_hint)) {
// cur and register_hint are not connected with two moves
return;
}
Interval* begin_hint = register_hint->split_child_at_op_id(begin_pos, LIR_OpVisitState::inputMode);
Interval* end_hint = register_hint->split_child_at_op_id(end_pos, LIR_OpVisitState::outputMode);
if (begin_hint == end_hint || begin_hint->to() != begin_pos || end_hint->from() != end_pos) {
// register_hint must be split, otherwise the re-writing of use positions does not work
return;
}
assert(begin_hint->assigned_reg() != any_reg, "must have register assigned");
assert(end_hint->assigned_reg() == any_reg, "must not have register assigned");
assert(cur->first_usage(mustHaveRegister) == begin_pos, "must have use position at begin of interval because of move");
assert(end_hint->first_usage(mustHaveRegister) == end_pos, "must have use position at begin of interval because of move");
if (begin_hint->assigned_reg() < LinearScan::nof_regs) {
// register_hint is not spilled at begin_pos, so it would not be benefitial to immediately spill cur
return;
}
assert(register_hint->canonical_spill_slot() != -1, "must be set when part of interval was spilled");
// modify intervals such that cur gets the same stack slot as register_hint
// delete use positions to prevent the intervals to get a register at beginning
cur->set_canonical_spill_slot(register_hint->canonical_spill_slot());
cur->remove_first_use_pos();
end_hint->remove_first_use_pos();
}
// allocate a physical register or memory location to an interval
bool LinearScanWalker::activate_current() {
Interval* cur = current();
bool result = true;
TRACE_LINEAR_SCAN(2, tty->print ("+++++ activating interval "); cur->print());
TRACE_LINEAR_SCAN(4, tty->print_cr(" split_parent: %d, insert_move_when_activated: %d", cur->split_parent()->reg_num(), cur->insert_move_when_activated()));
if (cur->assigned_reg() >= LinearScan::nof_regs) {
// activating an interval that has a stack slot assigned -> split it at first use position
// used for method parameters
TRACE_LINEAR_SCAN(4, tty->print_cr(" interval has spill slot assigned (method parameter) -> split it before first use"));
split_stack_interval(cur);
result = false;
} else if (allocator()->gen()->is_vreg_flag_set(cur->reg_num(), LIRGenerator::must_start_in_memory)) {
// activating an interval that must start in a stack slot, but may get a register later
// used for lir_roundfp: rounding is done by store to stack and reload later
TRACE_LINEAR_SCAN(4, tty->print_cr(" interval must start in stack slot -> split it before first use"));
assert(cur->assigned_reg() == any_reg && cur->assigned_regHi() == any_reg, "register already assigned");
allocator()->assign_spill_slot(cur);
split_stack_interval(cur);
result = false;
} else if (cur->assigned_reg() == any_reg) {
// interval has not assigned register -> normal allocation
// (this is the normal case for most intervals)
TRACE_LINEAR_SCAN(4, tty->print_cr(" normal allocation of register"));
// assign same spill slot to non-intersecting intervals
combine_spilled_intervals(cur);
init_vars_for_alloc(cur);
if (no_allocation_possible(cur) || !alloc_free_reg(cur)) {
// no empty register available.
// split and spill another interval so that this interval gets a register
alloc_locked_reg(cur);
}
// spilled intervals need not be move to active-list
if (cur->assigned_reg() >= LinearScan::nof_regs) {
result = false;
}
}
// load spilled values that become active from stack slot to register
if (cur->insert_move_when_activated()) {
assert(cur->is_split_child(), "must be");
assert(cur->current_split_child() != NULL, "must be");
assert(cur->current_split_child()->reg_num() != cur->reg_num(), "cannot insert move between same interval");
TRACE_LINEAR_SCAN(4, tty->print_cr("Inserting move from interval %d to %d because insert_move_when_activated is set", cur->current_split_child()->reg_num(), cur->reg_num()));
insert_move(cur->from(), cur->current_split_child(), cur);
}
cur->make_current_split_child();
return result; // true = interval is moved to active list
}
// Implementation of EdgeMoveOptimizer
EdgeMoveOptimizer::EdgeMoveOptimizer() :
_edge_instructions(4),
_edge_instructions_idx(4)
{
}
void EdgeMoveOptimizer::optimize(BlockList* code) {
EdgeMoveOptimizer optimizer = EdgeMoveOptimizer();
// ignore the first block in the list (index 0 is not processed)
for (int i = code->length() - 1; i >= 1; i--) {
BlockBegin* block = code->at(i);
if (block->number_of_preds() > 1 && !block->is_set(BlockBegin::exception_entry_flag)) {
optimizer.optimize_moves_at_block_end(block);
}
if (block->number_of_sux() == 2) {
optimizer.optimize_moves_at_block_begin(block);
}
}
}
// clear all internal data structures
void EdgeMoveOptimizer::init_instructions() {
_edge_instructions.clear();
_edge_instructions_idx.clear();
}
// append a lir-instruction-list and the index of the current operation in to the list
void EdgeMoveOptimizer::append_instructions(LIR_OpList* instructions, int instructions_idx) {
_edge_instructions.append(instructions);
_edge_instructions_idx.append(instructions_idx);
}
// return the current operation of the given edge (predecessor or successor)
LIR_Op* EdgeMoveOptimizer::instruction_at(int edge) {
LIR_OpList* instructions = _edge_instructions.at(edge);
int idx = _edge_instructions_idx.at(edge);
if (idx < instructions->length()) {
return instructions->at(idx);
} else {
return NULL;
}
}
// removes the current operation of the given edge (predecessor or successor)
void EdgeMoveOptimizer::remove_cur_instruction(int edge, bool decrement_index) {
LIR_OpList* instructions = _edge_instructions.at(edge);
int idx = _edge_instructions_idx.at(edge);
instructions->remove_at(idx);
if (decrement_index) {
_edge_instructions_idx.at_put(edge, idx - 1);
}
}
bool EdgeMoveOptimizer::operations_different(LIR_Op* op1, LIR_Op* op2) {
if (op1 == NULL || op2 == NULL) {
// at least one block is already empty -> no optimization possible
return true;
}
if (op1->code() == lir_move && op2->code() == lir_move) {
assert(op1->as_Op1() != NULL, "move must be LIR_Op1");
assert(op2->as_Op1() != NULL, "move must be LIR_Op1");
LIR_Op1* move1 = (LIR_Op1*)op1;
LIR_Op1* move2 = (LIR_Op1*)op2;
if (move1->info() == move2->info() && move1->in_opr() == move2->in_opr() && move1->result_opr() == move2->result_opr()) {
// these moves are exactly equal and can be optimized
return false;
}
} else if (op1->code() == lir_fxch && op2->code() == lir_fxch) {
assert(op1->as_Op1() != NULL, "fxch must be LIR_Op1");
assert(op2->as_Op1() != NULL, "fxch must be LIR_Op1");
LIR_Op1* fxch1 = (LIR_Op1*)op1;
LIR_Op1* fxch2 = (LIR_Op1*)op2;
if (fxch1->in_opr()->as_jint() == fxch2->in_opr()->as_jint()) {
// equal FPU stack operations can be optimized
return false;
}
} else if (op1->code() == lir_fpop_raw && op2->code() == lir_fpop_raw) {
// equal FPU stack operations can be optimized
return false;
}
// no optimization possible
return true;
}
void EdgeMoveOptimizer::optimize_moves_at_block_end(BlockBegin* block) {
TRACE_LINEAR_SCAN(4, tty->print_cr("optimizing moves at end of block B%d", block->block_id()));
if (block->is_predecessor(block)) {
// currently we can't handle this correctly.
return;
}
init_instructions();
int num_preds = block->number_of_preds();
assert(num_preds > 1, "do not call otherwise");
assert(!block->is_set(BlockBegin::exception_entry_flag), "exception handlers not allowed");
// setup a list with the lir-instructions of all predecessors
int i;
for (i = 0; i < num_preds; i++) {
BlockBegin* pred = block->pred_at(i);
LIR_OpList* pred_instructions = pred->lir()->instructions_list();
if (pred->number_of_sux() != 1) {
// this can happen with switch-statements where multiple edges are between
// the same blocks.
return;
}
assert(pred->number_of_sux() == 1, "can handle only one successor");
assert(pred->sux_at(0) == block, "invalid control flow");
assert(pred_instructions->last()->code() == lir_branch, "block with successor must end with branch");
assert(pred_instructions->last()->as_OpBranch() != NULL, "branch must be LIR_OpBranch");
assert(pred_instructions->last()->as_OpBranch()->cond() == lir_cond_always, "block must end with unconditional branch");
if (pred_instructions->last()->info() != NULL) {
// can not optimize instructions when debug info is needed
return;
}
// ignore the unconditional branch at the end of the block
append_instructions(pred_instructions, pred_instructions->length() - 2);
}
// process lir-instructions while all predecessors end with the same instruction
while (true) {
LIR_Op* op = instruction_at(0);
for (i = 1; i < num_preds; i++) {
if (operations_different(op, instruction_at(i))) {
// these instructions are different and cannot be optimized ->
// no further optimization possible
return;
}
}
TRACE_LINEAR_SCAN(4, tty->print("found instruction that is equal in all %d predecessors: ", num_preds); op->print());
// insert the instruction at the beginning of the current block
block->lir()->insert_before(1, op);
// delete the instruction at the end of all predecessors
for (i = 0; i < num_preds; i++) {
remove_cur_instruction(i, true);
}
}
}
void EdgeMoveOptimizer::optimize_moves_at_block_begin(BlockBegin* block) {
TRACE_LINEAR_SCAN(4, tty->print_cr("optimization moves at begin of block B%d", block->block_id()));
init_instructions();
int num_sux = block->number_of_sux();
LIR_OpList* cur_instructions = block->lir()->instructions_list();
assert(num_sux == 2, "method should not be called otherwise");
assert(cur_instructions->last()->code() == lir_branch, "block with successor must end with branch");
assert(cur_instructions->last()->as_OpBranch() != NULL, "branch must be LIR_OpBranch");
assert(cur_instructions->last()->as_OpBranch()->cond() == lir_cond_always, "block must end with unconditional branch");
if (cur_instructions->last()->info() != NULL) {
// can no optimize instructions when debug info is needed
return;
}
LIR_Op* branch = cur_instructions->at(cur_instructions->length() - 2);
if (branch->info() != NULL || (branch->code() != lir_branch && branch->code() != lir_cond_float_branch)) {
// not a valid case for optimization
// currently, only blocks that end with two branches (conditional branch followed
// by unconditional branch) are optimized
return;
}
// now it is guaranteed that the block ends with two branch instructions.
// the instructions are inserted at the end of the block before these two branches
int insert_idx = cur_instructions->length() - 2;
int i;
#ifdef ASSERT
for (i = insert_idx - 1; i >= 0; i--) {
LIR_Op* op = cur_instructions->at(i);
if ((op->code() == lir_branch || op->code() == lir_cond_float_branch) && ((LIR_OpBranch*)op)->block() != NULL) {
assert(false, "block with two successors can have only two branch instructions");
}
}
#endif
// setup a list with the lir-instructions of all successors
for (i = 0; i < num_sux; i++) {
BlockBegin* sux = block->sux_at(i);
LIR_OpList* sux_instructions = sux->lir()->instructions_list();
assert(sux_instructions->at(0)->code() == lir_label, "block must start with label");
if (sux->number_of_preds() != 1) {
// this can happen with switch-statements where multiple edges are between
// the same blocks.
return;
}
assert(sux->pred_at(0) == block, "invalid control flow");
assert(!sux->is_set(BlockBegin::exception_entry_flag), "exception handlers not allowed");
// ignore the label at the beginning of the block
append_instructions(sux_instructions, 1);
}
// process lir-instructions while all successors begin with the same instruction
while (true) {
LIR_Op* op = instruction_at(0);
for (i = 1; i < num_sux; i++) {
if (operations_different(op, instruction_at(i))) {
// these instructions are different and cannot be optimized ->
// no further optimization possible
return;
}
}
TRACE_LINEAR_SCAN(4, tty->print("----- found instruction that is equal in all %d successors: ", num_sux); op->print());
// insert instruction at end of current block
block->lir()->insert_before(insert_idx, op);
insert_idx++;
// delete the instructions at the beginning of all successors
for (i = 0; i < num_sux; i++) {
remove_cur_instruction(i, false);
}
}
}
// Implementation of ControlFlowOptimizer
ControlFlowOptimizer::ControlFlowOptimizer() :
_original_preds(4)
{
}
void ControlFlowOptimizer::optimize(BlockList* code) {
ControlFlowOptimizer optimizer = ControlFlowOptimizer();
// push the OSR entry block to the end so that we're not jumping over it.
BlockBegin* osr_entry = code->at(0)->end()->as_Base()->osr_entry();
if (osr_entry) {
int index = osr_entry->linear_scan_number();
assert(code->at(index) == osr_entry, "wrong index");
code->remove_at(index);
code->append(osr_entry);
}
optimizer.reorder_short_loops(code);
optimizer.delete_empty_blocks(code);
optimizer.delete_unnecessary_jumps(code);
optimizer.delete_jumps_to_return(code);
}
void ControlFlowOptimizer::reorder_short_loop(BlockList* code, BlockBegin* header_block, int header_idx) {
int i = header_idx + 1;
int max_end = MIN2(header_idx + ShortLoopSize, code->length());
while (i < max_end && code->at(i)->loop_depth() >= header_block->loop_depth()) {
i++;
}
if (i == code->length() || code->at(i)->loop_depth() < header_block->loop_depth()) {
int end_idx = i - 1;
BlockBegin* end_block = code->at(end_idx);
if (end_block->number_of_sux() == 1 && end_block->sux_at(0) == header_block) {
// short loop from header_idx to end_idx found -> reorder blocks such that
// the header_block is the last block instead of the first block of the loop
TRACE_LINEAR_SCAN(1, tty->print_cr("Reordering short loop: length %d, header B%d, end B%d",
end_idx - header_idx + 1,
header_block->block_id(), end_block->block_id()));
for (int j = header_idx; j < end_idx; j++) {
code->at_put(j, code->at(j + 1));
}
code->at_put(end_idx, header_block);
// correct the flags so that any loop alignment occurs in the right place.
assert(code->at(end_idx)->is_set(BlockBegin::backward_branch_target_flag), "must be backward branch target");
code->at(end_idx)->clear(BlockBegin::backward_branch_target_flag);
code->at(header_idx)->set(BlockBegin::backward_branch_target_flag);
}
}
}
void ControlFlowOptimizer::reorder_short_loops(BlockList* code) {
for (int i = code->length() - 1; i >= 0; i--) {
BlockBegin* block = code->at(i);
if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) {
reorder_short_loop(code, block, i);
}
}
DEBUG_ONLY(verify(code));
}
// only blocks with exactly one successor can be deleted. Such blocks
// must always end with an unconditional branch to this successor
bool ControlFlowOptimizer::can_delete_block(BlockBegin* block) {
if (block->number_of_sux() != 1 || block->number_of_exception_handlers() != 0 || block->is_entry_block()) {
return false;
}
LIR_OpList* instructions = block->lir()->instructions_list();
assert(instructions->length() >= 2, "block must have label and branch");
assert(instructions->at(0)->code() == lir_label, "first instruction must always be a label");
assert(instructions->last()->as_OpBranch() != NULL, "last instrcution must always be a branch");
assert(instructions->last()->as_OpBranch()->cond() == lir_cond_always, "branch must be unconditional");
assert(instructions->last()->as_OpBranch()->block() == block->sux_at(0), "branch target must be the successor");
// block must have exactly one successor
if (instructions->length() == 2 && instructions->last()->info() == NULL) {
return true;
}
return false;
}
// substitute branch targets in all branch-instructions of this blocks
void ControlFlowOptimizer::substitute_branch_target(BlockBegin* block, BlockBegin* target_from, BlockBegin* target_to) {
TRACE_LINEAR_SCAN(3, tty->print_cr("Deleting empty block: substituting from B%d to B%d inside B%d", target_from->block_id(), target_to->block_id(), block->block_id()));
LIR_OpList* instructions = block->lir()->instructions_list();
assert(instructions->at(0)->code() == lir_label, "first instruction must always be a label");
for (int i = instructions->length() - 1; i >= 1; i--) {
LIR_Op* op = instructions->at(i);
if (op->code() == lir_branch || op->code() == lir_cond_float_branch) {
assert(op->as_OpBranch() != NULL, "branch must be of type LIR_OpBranch");
LIR_OpBranch* branch = (LIR_OpBranch*)op;
if (branch->block() == target_from) {
branch->change_block(target_to);
}
if (branch->ublock() == target_from) {
branch->change_ublock(target_to);
}
}
}
}
void ControlFlowOptimizer::delete_empty_blocks(BlockList* code) {
int old_pos = 0;
int new_pos = 0;
int num_blocks = code->length();
while (old_pos < num_blocks) {
BlockBegin* block = code->at(old_pos);
if (can_delete_block(block)) {
BlockBegin* new_target = block->sux_at(0);
// propagate backward branch target flag for correct code alignment
if (block->is_set(BlockBegin::backward_branch_target_flag)) {
new_target->set(BlockBegin::backward_branch_target_flag);
}
// collect a list with all predecessors that contains each predecessor only once
// the predecessors of cur are changed during the substitution, so a copy of the
// predecessor list is necessary
int j;
_original_preds.clear();
for (j = block->number_of_preds() - 1; j >= 0; j--) {
BlockBegin* pred = block->pred_at(j);
if (_original_preds.index_of(pred) == -1) {
_original_preds.append(pred);
}
}
for (j = _original_preds.length() - 1; j >= 0; j--) {
BlockBegin* pred = _original_preds.at(j);
substitute_branch_target(pred, block, new_target);
pred->substitute_sux(block, new_target);
}
} else {
// adjust position of this block in the block list if blocks before
// have been deleted
if (new_pos != old_pos) {
code->at_put(new_pos, code->at(old_pos));
}
new_pos++;
}
old_pos++;
}
code->truncate(new_pos);
DEBUG_ONLY(verify(code));
}
void ControlFlowOptimizer::delete_unnecessary_jumps(BlockList* code) {
// skip the last block because there a branch is always necessary
for (int i = code->length() - 2; i >= 0; i--) {
BlockBegin* block = code->at(i);
LIR_OpList* instructions = block->lir()->instructions_list();
LIR_Op* last_op = instructions->last();
if (last_op->code() == lir_branch) {
assert(last_op->as_OpBranch() != NULL, "branch must be of type LIR_OpBranch");
LIR_OpBranch* last_branch = (LIR_OpBranch*)last_op;
assert(last_branch->block() != NULL, "last branch must always have a block as target");
assert(last_branch->label() == last_branch->block()->label(), "must be equal");
if (last_branch->info() == NULL) {
if (last_branch->block() == code->at(i + 1)) {
TRACE_LINEAR_SCAN(3, tty->print_cr("Deleting unconditional branch at end of block B%d", block->block_id()));
// delete last branch instruction
instructions->truncate(instructions->length() - 1);
} else {
LIR_Op* prev_op = instructions->at(instructions->length() - 2);
if (prev_op->code() == lir_branch || prev_op->code() == lir_cond_float_branch) {
assert(prev_op->as_OpBranch() != NULL, "branch must be of type LIR_OpBranch");
LIR_OpBranch* prev_branch = (LIR_OpBranch*)prev_op;
if (prev_branch->stub() == NULL) {
LIR_Op2* prev_cmp = NULL;
for(int j = instructions->length() - 3; j >= 0 && prev_cmp == NULL; j--) {
prev_op = instructions->at(j);
if (prev_op->code() == lir_cmp) {
assert(prev_op->as_Op2() != NULL, "branch must be of type LIR_Op2");
prev_cmp = (LIR_Op2*)prev_op;
assert(prev_branch->cond() == prev_cmp->condition(), "should be the same");
}
}
assert(prev_cmp != NULL, "should have found comp instruction for branch");
if (prev_branch->block() == code->at(i + 1) && prev_branch->info() == NULL) {
TRACE_LINEAR_SCAN(3, tty->print_cr("Negating conditional branch and deleting unconditional branch at end of block B%d", block->block_id()));
// eliminate a conditional branch to the immediate successor
prev_branch->change_block(last_branch->block());
prev_branch->negate_cond();
prev_cmp->set_condition(prev_branch->cond());
instructions->truncate(instructions->length() - 1);
}
}
}
}
}
}
}
DEBUG_ONLY(verify(code));
}
void ControlFlowOptimizer::delete_jumps_to_return(BlockList* code) {
#ifdef ASSERT
BitMap return_converted(BlockBegin::number_of_blocks());
return_converted.clear();
#endif
for (int i = code->length() - 1; i >= 0; i--) {
BlockBegin* block = code->at(i);
LIR_OpList* cur_instructions = block->lir()->instructions_list();
LIR_Op* cur_last_op = cur_instructions->last();
assert(cur_instructions->at(0)->code() == lir_label, "first instruction must always be a label");
if (cur_instructions->length() == 2 && cur_last_op->code() == lir_return) {
// the block contains only a label and a return
// if a predecessor ends with an unconditional jump to this block, then the jump
// can be replaced with a return instruction
//
// Note: the original block with only a return statement cannot be deleted completely
// because the predecessors might have other (conditional) jumps to this block
// -> this may lead to unnecesary return instructions in the final code
assert(cur_last_op->info() == NULL, "return instructions do not have debug information");
assert(block->number_of_sux() == 0 ||
(return_converted.at(block->block_id()) && block->number_of_sux() == 1),
"blocks that end with return must not have successors");
assert(cur_last_op->as_Op1() != NULL, "return must be LIR_Op1");
LIR_Opr return_opr = ((LIR_Op1*)cur_last_op)->in_opr();
for (int j = block->number_of_preds() - 1; j >= 0; j--) {
BlockBegin* pred = block->pred_at(j);
LIR_OpList* pred_instructions = pred->lir()->instructions_list();
LIR_Op* pred_last_op = pred_instructions->last();
if (pred_last_op->code() == lir_branch) {
assert(pred_last_op->as_OpBranch() != NULL, "branch must be LIR_OpBranch");
LIR_OpBranch* pred_last_branch = (LIR_OpBranch*)pred_last_op;
if (pred_last_branch->block() == block && pred_last_branch->cond() == lir_cond_always && pred_last_branch->info() == NULL) {
// replace the jump to a return with a direct return
// Note: currently the edge between the blocks is not deleted
pred_instructions->at_put(pred_instructions->length() - 1, new LIR_Op1(lir_return, return_opr));
#ifdef ASSERT
return_converted.set_bit(pred->block_id());
#endif
}
}
}
}
}
}
#ifdef ASSERT
void ControlFlowOptimizer::verify(BlockList* code) {
for (int i = 0; i < code->length(); i++) {
BlockBegin* block = code->at(i);
LIR_OpList* instructions = block->lir()->instructions_list();
int j;
for (j = 0; j < instructions->length(); j++) {
LIR_OpBranch* op_branch = instructions->at(j)->as_OpBranch();
if (op_branch != NULL) {
assert(op_branch->block() == NULL || code->index_of(op_branch->block()) != -1, "branch target not valid");
assert(op_branch->ublock() == NULL || code->index_of(op_branch->ublock()) != -1, "branch target not valid");
}
}
for (j = 0; j < block->number_of_sux() - 1; j++) {
BlockBegin* sux = block->sux_at(j);
assert(code->index_of(sux) != -1, "successor not valid");
}
for (j = 0; j < block->number_of_preds() - 1; j++) {
BlockBegin* pred = block->pred_at(j);
assert(code->index_of(pred) != -1, "successor not valid");
}
}
}
#endif
#ifndef PRODUCT
// Implementation of LinearStatistic
const char* LinearScanStatistic::counter_name(int counter_idx) {
switch (counter_idx) {
case counter_method: return "compiled methods";
case counter_fpu_method: return "methods using fpu";
case counter_loop_method: return "methods with loops";
case counter_exception_method:return "methods with xhandler";
case counter_loop: return "loops";
case counter_block: return "blocks";
case counter_loop_block: return "blocks inside loop";
case counter_exception_block: return "exception handler entries";
case counter_interval: return "intervals";
case counter_fixed_interval: return "fixed intervals";
case counter_range: return "ranges";
case counter_fixed_range: return "fixed ranges";
case counter_use_pos: return "use positions";
case counter_fixed_use_pos: return "fixed use positions";
case counter_spill_slots: return "spill slots";
// counter for classes of lir instructions
case counter_instruction: return "total instructions";
case counter_label: return "labels";
case counter_entry: return "method entries";
case counter_return: return "method returns";
case counter_call: return "method calls";
case counter_move: return "moves";
case counter_cmp: return "compare";
case counter_cond_branch: return "conditional branches";
case counter_uncond_branch: return "unconditional branches";
case counter_stub_branch: return "branches to stub";
case counter_alu: return "artithmetic + logic";
case counter_alloc: return "allocations";
case counter_sync: return "synchronisation";
case counter_throw: return "throw";
case counter_unwind: return "unwind";
case counter_typecheck: return "type+null-checks";
case counter_fpu_stack: return "fpu-stack";
case counter_misc_inst: return "other instructions";
case counter_other_inst: return "misc. instructions";
// counter for different types of moves
case counter_move_total: return "total moves";
case counter_move_reg_reg: return "register->register";
case counter_move_reg_stack: return "register->stack";
case counter_move_stack_reg: return "stack->register";
case counter_move_stack_stack:return "stack->stack";
case counter_move_reg_mem: return "register->memory";
case counter_move_mem_reg: return "memory->register";
case counter_move_const_any: return "constant->any";
case blank_line_1: return "";
case blank_line_2: return "";
default: ShouldNotReachHere(); return "";
}
}
LinearScanStatistic::Counter LinearScanStatistic::base_counter(int counter_idx) {
if (counter_idx == counter_fpu_method || counter_idx == counter_loop_method || counter_idx == counter_exception_method) {
return counter_method;
} else if (counter_idx == counter_loop_block || counter_idx == counter_exception_block) {
return counter_block;
} else if (counter_idx >= counter_instruction && counter_idx <= counter_other_inst) {
return counter_instruction;
} else if (counter_idx >= counter_move_total && counter_idx <= counter_move_const_any) {
return counter_move_total;
}
return invalid_counter;
}
LinearScanStatistic::LinearScanStatistic() {
for (int i = 0; i < number_of_counters; i++) {
_counters_sum[i] = 0;
_counters_max[i] = -1;
}
}
// add the method-local numbers to the total sum
void LinearScanStatistic::sum_up(LinearScanStatistic &method_statistic) {
for (int i = 0; i < number_of_counters; i++) {
_counters_sum[i] += method_statistic._counters_sum[i];
_counters_max[i] = MAX2(_counters_max[i], method_statistic._counters_sum[i]);
}
}
void LinearScanStatistic::print(const char* title) {
if (CountLinearScan || TraceLinearScanLevel > 0) {
tty->cr();
tty->print_cr("***** LinearScan statistic - %s *****", title);
for (int i = 0; i < number_of_counters; i++) {
if (_counters_sum[i] > 0 || _counters_max[i] >= 0) {
tty->print("%25s: %8d", counter_name(i), _counters_sum[i]);
if (base_counter(i) != invalid_counter) {
tty->print(" (%5.1f%%) ", _counters_sum[i] * 100.0 / _counters_sum[base_counter(i)]);
} else {
tty->print(" ");
}
if (_counters_max[i] >= 0) {
tty->print("%8d", _counters_max[i]);
}
}
tty->cr();
}
}
}
void LinearScanStatistic::collect(LinearScan* allocator) {
inc_counter(counter_method);
if (allocator->has_fpu_registers()) {
inc_counter(counter_fpu_method);
}
if (allocator->num_loops() > 0) {
inc_counter(counter_loop_method);
}
inc_counter(counter_loop, allocator->num_loops());
inc_counter(counter_spill_slots, allocator->max_spills());
int i;
for (i = 0; i < allocator->interval_count(); i++) {
Interval* cur = allocator->interval_at(i);
if (cur != NULL) {
inc_counter(counter_interval);
inc_counter(counter_use_pos, cur->num_use_positions());
if (LinearScan::is_precolored_interval(cur)) {
inc_counter(counter_fixed_interval);
inc_counter(counter_fixed_use_pos, cur->num_use_positions());
}
Range* range = cur->first();
while (range != Range::end()) {
inc_counter(counter_range);
if (LinearScan::is_precolored_interval(cur)) {
inc_counter(counter_fixed_range);
}
range = range->next();
}
}
}
bool has_xhandlers = false;
// Note: only count blocks that are in code-emit order
for (i = 0; i < allocator->ir()->code()->length(); i++) {
BlockBegin* cur = allocator->ir()->code()->at(i);
inc_counter(counter_block);
if (cur->loop_depth() > 0) {
inc_counter(counter_loop_block);
}
if (cur->is_set(BlockBegin::exception_entry_flag)) {
inc_counter(counter_exception_block);
has_xhandlers = true;
}
LIR_OpList* instructions = cur->lir()->instructions_list();
for (int j = 0; j < instructions->length(); j++) {
LIR_Op* op = instructions->at(j);
inc_counter(counter_instruction);
switch (op->code()) {
case lir_label: inc_counter(counter_label); break;
case lir_std_entry:
case lir_osr_entry: inc_counter(counter_entry); break;
case lir_return: inc_counter(counter_return); break;
case lir_rtcall:
case lir_static_call:
case lir_optvirtual_call:
case lir_virtual_call: inc_counter(counter_call); break;
case lir_move: {
inc_counter(counter_move);
inc_counter(counter_move_total);
LIR_Opr in = op->as_Op1()->in_opr();
LIR_Opr res = op->as_Op1()->result_opr();
if (in->is_register()) {
if (res->is_register()) {
inc_counter(counter_move_reg_reg);
} else if (res->is_stack()) {
inc_counter(counter_move_reg_stack);
} else if (res->is_address()) {
inc_counter(counter_move_reg_mem);
} else {
ShouldNotReachHere();
}
} else if (in->is_stack()) {
if (res->is_register()) {
inc_counter(counter_move_stack_reg);
} else {
inc_counter(counter_move_stack_stack);
}
} else if (in->is_address()) {
assert(res->is_register(), "must be");
inc_counter(counter_move_mem_reg);
} else if (in->is_constant()) {
inc_counter(counter_move_const_any);
} else {
ShouldNotReachHere();
}
break;
}
case lir_cmp: inc_counter(counter_cmp); break;
case lir_branch:
case lir_cond_float_branch: {
LIR_OpBranch* branch = op->as_OpBranch();
if (branch->block() == NULL) {
inc_counter(counter_stub_branch);
} else if (branch->cond() == lir_cond_always) {
inc_counter(counter_uncond_branch);
} else {
inc_counter(counter_cond_branch);
}
break;
}
case lir_neg:
case lir_add:
case lir_sub:
case lir_mul:
case lir_mul_strictfp:
case lir_div:
case lir_div_strictfp:
case lir_rem:
case lir_sqrt:
case lir_sin:
case lir_cos:
case lir_abs:
case lir_log10:
case lir_log:
case lir_pow:
case lir_exp:
case lir_logic_and:
case lir_logic_or:
case lir_logic_xor:
case lir_shl:
case lir_shr:
case lir_ushr: inc_counter(counter_alu); break;
case lir_alloc_object:
case lir_alloc_array: inc_counter(counter_alloc); break;
case lir_monaddr:
case lir_lock:
case lir_unlock: inc_counter(counter_sync); break;
case lir_throw: inc_counter(counter_throw); break;
case lir_unwind: inc_counter(counter_unwind); break;
case lir_null_check:
case lir_leal:
case lir_instanceof:
case lir_checkcast:
case lir_store_check: inc_counter(counter_typecheck); break;
case lir_fpop_raw:
case lir_fxch:
case lir_fld: inc_counter(counter_fpu_stack); break;
case lir_nop:
case lir_push:
case lir_pop:
case lir_convert:
case lir_roundfp:
case lir_cmove: inc_counter(counter_misc_inst); break;
default: inc_counter(counter_other_inst); break;
}
}
}
if (has_xhandlers) {
inc_counter(counter_exception_method);
}
}
void LinearScanStatistic::compute(LinearScan* allocator, LinearScanStatistic &global_statistic) {
if (CountLinearScan || TraceLinearScanLevel > 0) {
LinearScanStatistic local_statistic = LinearScanStatistic();
local_statistic.collect(allocator);
global_statistic.sum_up(local_statistic);
if (TraceLinearScanLevel > 2) {
local_statistic.print("current local statistic");
}
}
}
// Implementation of LinearTimers
LinearScanTimers::LinearScanTimers() {
for (int i = 0; i < number_of_timers; i++) {
timer(i)->reset();
}
}
const char* LinearScanTimers::timer_name(int idx) {
switch (idx) {
case timer_do_nothing: return "Nothing (Time Check)";
case timer_number_instructions: return "Number Instructions";
case timer_compute_local_live_sets: return "Local Live Sets";
case timer_compute_global_live_sets: return "Global Live Sets";
case timer_build_intervals: return "Build Intervals";
case timer_sort_intervals_before: return "Sort Intervals Before";
case timer_allocate_registers: return "Allocate Registers";
case timer_resolve_data_flow: return "Resolve Data Flow";
case timer_sort_intervals_after: return "Sort Intervals After";
case timer_eliminate_spill_moves: return "Spill optimization";
case timer_assign_reg_num: return "Assign Reg Num";
case timer_allocate_fpu_stack: return "Allocate FPU Stack";
case timer_optimize_lir: return "Optimize LIR";
default: ShouldNotReachHere(); return "";
}
}
void LinearScanTimers::begin_method() {
if (TimeEachLinearScan) {
// reset all timers to measure only current method
for (int i = 0; i < number_of_timers; i++) {
timer(i)->reset();
}
}
}
void LinearScanTimers::end_method(LinearScan* allocator) {
if (TimeEachLinearScan) {
double c = timer(timer_do_nothing)->seconds();
double total = 0;
for (int i = 1; i < number_of_timers; i++) {
total += timer(i)->seconds() - c;
}
if (total >= 0.0005) {
// print all information in one line for automatic processing
tty->print("@"); allocator->compilation()->method()->print_name();
tty->print("@ %d ", allocator->compilation()->method()->code_size());
tty->print("@ %d ", allocator->block_at(allocator->block_count() - 1)->last_lir_instruction_id() / 2);
tty->print("@ %d ", allocator->block_count());
tty->print("@ %d ", allocator->num_virtual_regs());
tty->print("@ %d ", allocator->interval_count());
tty->print("@ %d ", allocator->_num_calls);
tty->print("@ %d ", allocator->num_loops());
tty->print("@ %6.6f ", total);
for (int i = 1; i < number_of_timers; i++) {
tty->print("@ %4.1f ", ((timer(i)->seconds() - c) / total) * 100);
}
tty->cr();
}
}
}
void LinearScanTimers::print(double total_time) {
if (TimeLinearScan) {
// correction value: sum of dummy-timer that only measures the time that
// is necesary to start and stop itself
double c = timer(timer_do_nothing)->seconds();
for (int i = 0; i < number_of_timers; i++) {
double t = timer(i)->seconds();
tty->print_cr(" %25s: %6.3f s (%4.1f%%) corrected: %6.3f s (%4.1f%%)", timer_name(i), t, (t / total_time) * 100.0, t - c, (t - c) / (total_time - 2 * number_of_timers * c) * 100);
}
}
}
#endif // #ifndef PRODUCT
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