Java example source code file (cfgnode.cpp)
The cfgnode.cpp Java example source code/*
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* version 2 for more details (a copy is included in the LICENSE file that
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#include "precompiled.hpp"
#include "classfile/systemDictionary.hpp"
#include "memory/allocation.inline.hpp"
#include "oops/objArrayKlass.hpp"
#include "opto/addnode.hpp"
#include "opto/cfgnode.hpp"
#include "opto/connode.hpp"
#include "opto/loopnode.hpp"
#include "opto/machnode.hpp"
#include "opto/mulnode.hpp"
#include "opto/phaseX.hpp"
#include "opto/regmask.hpp"
#include "opto/runtime.hpp"
#include "opto/subnode.hpp"
// Portions of code courtesy of Clifford Click
// Optimization - Graph Style
//=============================================================================
//------------------------------Value------------------------------------------
// Compute the type of the RegionNode.
const Type *RegionNode::Value( PhaseTransform *phase ) const {
for( uint i=1; i<req(); ++i ) { // For all paths in
Node *n = in(i); // Get Control source
if( !n ) continue; // Missing inputs are TOP
if( phase->type(n) == Type::CONTROL )
return Type::CONTROL;
}
return Type::TOP; // All paths dead? Then so are we
}
//------------------------------Identity---------------------------------------
// Check for Region being Identity.
Node *RegionNode::Identity( PhaseTransform *phase ) {
// Cannot have Region be an identity, even if it has only 1 input.
// Phi users cannot have their Region input folded away for them,
// since they need to select the proper data input
return this;
}
//------------------------------merge_region-----------------------------------
// If a Region flows into a Region, merge into one big happy merge. This is
// hard to do if there is stuff that has to happen
static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
return NULL;
Node *progress = NULL; // Progress flag
PhaseIterGVN *igvn = phase->is_IterGVN();
uint rreq = region->req();
for( uint i = 1; i < rreq; i++ ) {
Node *r = region->in(i);
if( r && r->Opcode() == Op_Region && // Found a region?
r->in(0) == r && // Not already collapsed?
r != region && // Avoid stupid situations
r->outcnt() == 2 ) { // Self user and 'region' user only?
assert(!r->as_Region()->has_phi(), "no phi users");
if( !progress ) { // No progress
if (region->has_phi()) {
return NULL; // Only flatten if no Phi users
// igvn->hash_delete( phi );
}
igvn->hash_delete( region );
progress = region; // Making progress
}
igvn->hash_delete( r );
// Append inputs to 'r' onto 'region'
for( uint j = 1; j < r->req(); j++ ) {
// Move an input from 'r' to 'region'
region->add_req(r->in(j));
r->set_req(j, phase->C->top());
// Update phis of 'region'
//for( uint k = 0; k < max; k++ ) {
// Node *phi = region->out(k);
// if( phi->is_Phi() ) {
// phi->add_req(phi->in(i));
// }
//}
rreq++; // One more input to Region
} // Found a region to merge into Region
// Clobber pointer to the now dead 'r'
region->set_req(i, phase->C->top());
}
}
return progress;
}
//--------------------------------has_phi--------------------------------------
// Helper function: Return any PhiNode that uses this region or NULL
PhiNode* RegionNode::has_phi() const {
for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
Node* phi = fast_out(i);
if (phi->is_Phi()) { // Check for Phi users
assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
return phi->as_Phi(); // this one is good enough
}
}
return NULL;
}
//-----------------------------has_unique_phi----------------------------------
// Helper function: Return the only PhiNode that uses this region or NULL
PhiNode* RegionNode::has_unique_phi() const {
// Check that only one use is a Phi
PhiNode* only_phi = NULL;
for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
Node* phi = fast_out(i);
if (phi->is_Phi()) { // Check for Phi users
assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
if (only_phi == NULL) {
only_phi = phi->as_Phi();
} else {
return NULL; // multiple phis
}
}
}
return only_phi;
}
//------------------------------check_phi_clipping-----------------------------
// Helper function for RegionNode's identification of FP clipping
// Check inputs to the Phi
static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
min = NULL;
max = NULL;
val = NULL;
min_idx = 0;
max_idx = 0;
val_idx = 0;
uint phi_max = phi->req();
if( phi_max == 4 ) {
for( uint j = 1; j < phi_max; ++j ) {
Node *n = phi->in(j);
int opcode = n->Opcode();
switch( opcode ) {
case Op_ConI:
{
if( min == NULL ) {
min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
min_idx = j;
} else {
max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
max_idx = j;
if( min->get_int() > max->get_int() ) {
// Swap min and max
ConNode *temp;
uint temp_idx;
temp = min; min = max; max = temp;
temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
}
}
}
break;
default:
{
val = n;
val_idx = j;
}
break;
}
}
}
return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
}
//------------------------------check_if_clipping------------------------------
// Helper function for RegionNode's identification of FP clipping
// Check that inputs to Region come from two IfNodes,
//
// If
// False True
// If |
// False True |
// | | |
// RegionNode_inputs
//
static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
top_if = NULL;
bot_if = NULL;
// Check control structure above RegionNode for (if ( if ) )
Node *in1 = region->in(1);
Node *in2 = region->in(2);
Node *in3 = region->in(3);
// Check that all inputs are projections
if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
Node *in10 = in1->in(0);
Node *in20 = in2->in(0);
Node *in30 = in3->in(0);
// Check that #1 and #2 are ifTrue and ifFalse from same If
if( in10 != NULL && in10->is_If() &&
in20 != NULL && in20->is_If() &&
in30 != NULL && in30->is_If() && in10 == in20 &&
(in1->Opcode() != in2->Opcode()) ) {
Node *in100 = in10->in(0);
Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
// Check that control for in10 comes from other branch of IF from in3
if( in1000 != NULL && in1000->is_If() &&
in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
// Control pattern checks
top_if = (IfNode*)in1000;
bot_if = (IfNode*)in10;
}
}
}
return (top_if != NULL);
}
//------------------------------check_convf2i_clipping-------------------------
// Helper function for RegionNode's identification of FP clipping
// Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
convf2i = NULL;
// Check for the RShiftNode
Node *rshift = phi->in(idx);
assert( rshift, "Previous checks ensure phi input is present");
if( rshift->Opcode() != Op_RShiftI ) { return false; }
// Check for the LShiftNode
Node *lshift = rshift->in(1);
assert( lshift, "Previous checks ensure phi input is present");
if( lshift->Opcode() != Op_LShiftI ) { return false; }
// Check for the ConvF2INode
Node *conv = lshift->in(1);
if( conv->Opcode() != Op_ConvF2I ) { return false; }
// Check that shift amounts are only to get sign bits set after F2I
jint max_cutoff = max->get_int();
jint min_cutoff = min->get_int();
jint left_shift = lshift->in(2)->get_int();
jint right_shift = rshift->in(2)->get_int();
jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
if( left_shift != right_shift ||
0 > left_shift || left_shift >= BitsPerJavaInteger ||
max_post_shift < max_cutoff ||
max_post_shift < -min_cutoff ) {
// Shifts are necessary but current transformation eliminates them
return false;
}
// OK to return the result of ConvF2I without shifting
convf2i = (ConvF2INode*)conv;
return true;
}
//------------------------------check_compare_clipping-------------------------
// Helper function for RegionNode's identification of FP clipping
static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
Node *i1 = iff->in(1);
if ( !i1->is_Bool() ) { return false; }
BoolNode *bool1 = i1->as_Bool();
if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
const Node *cmpF = bool1->in(1);
if( cmpF->Opcode() != Op_CmpF ) { return false; }
// Test that the float value being compared against
// is equivalent to the int value used as a limit
Node *nodef = cmpF->in(2);
if( nodef->Opcode() != Op_ConF ) { return false; }
jfloat conf = nodef->getf();
jint coni = limit->get_int();
if( ((int)conf) != coni ) { return false; }
input = cmpF->in(1);
return true;
}
//------------------------------is_unreachable_region--------------------------
// Find if the Region node is reachable from the root.
bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
assert(req() == 2, "");
// First, cut the simple case of fallthrough region when NONE of
// region's phis references itself directly or through a data node.
uint max = outcnt();
uint i;
for (i = 0; i < max; i++) {
Node* phi = raw_out(i);
if (phi != NULL && phi->is_Phi()) {
assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
if (phi->outcnt() == 0)
continue; // Safe case - no loops
if (phi->outcnt() == 1) {
Node* u = phi->raw_out(0);
// Skip if only one use is an other Phi or Call or Uncommon trap.
// It is safe to consider this case as fallthrough.
if (u != NULL && (u->is_Phi() || u->is_CFG()))
continue;
}
// Check when phi references itself directly or through an other node.
if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
break; // Found possible unsafe data loop.
}
}
if (i >= max)
return false; // An unsafe case was NOT found - don't need graph walk.
// Unsafe case - check if the Region node is reachable from root.
ResourceMark rm;
Arena *a = Thread::current()->resource_area();
Node_List nstack(a);
VectorSet visited(a);
// Mark all control nodes reachable from root outputs
Node *n = (Node*)phase->C->root();
nstack.push(n);
visited.set(n->_idx);
while (nstack.size() != 0) {
n = nstack.pop();
uint max = n->outcnt();
for (uint i = 0; i < max; i++) {
Node* m = n->raw_out(i);
if (m != NULL && m->is_CFG()) {
if (phase->eqv(m, this)) {
return false; // We reached the Region node - it is not dead.
}
if (!visited.test_set(m->_idx))
nstack.push(m);
}
}
}
return true; // The Region node is unreachable - it is dead.
}
bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
// Incremental inlining + PhaseStringOpts sometimes produce:
//
// cmpP with 1 top input
// |
// If
// / \
// IfFalse IfTrue /- Some Node
// \ / / /
// Region / /-MergeMem
// \---Phi
//
//
// It's expected by PhaseStringOpts that the Region goes away and is
// replaced by If's control input but because there's still a Phi,
// the Region stays in the graph. The top input from the cmpP is
// propagated forward and a subgraph that is useful goes away. The
// code below replaces the Phi with the MergeMem so that the Region
// is simplified.
PhiNode* phi = has_unique_phi();
if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
MergeMemNode* m = NULL;
assert(phi->req() == 3, "same as region");
for (uint i = 1; i < 3; ++i) {
Node *mem = phi->in(i);
if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
// Nothing is control-dependent on path #i except the region itself.
m = mem->as_MergeMem();
uint j = 3 - i;
Node* other = phi->in(j);
if (other && other == m->base_memory()) {
// m is a successor memory to other, and is not pinned inside the diamond, so push it out.
// This will allow the diamond to collapse completely.
phase->is_IterGVN()->replace_node(phi, m);
return true;
}
}
}
}
return false;
}
//------------------------------Ideal------------------------------------------
// Return a node which is more "ideal" than the current node. Must preserve
// the CFG, but we can still strip out dead paths.
Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
// Check for RegionNode with no Phi users and both inputs come from either
// arm of the same IF. If found, then the control-flow split is useless.
bool has_phis = false;
if (can_reshape) { // Need DU info to check for Phi users
has_phis = (has_phi() != NULL); // Cache result
if (has_phis && try_clean_mem_phi(phase)) {
has_phis = false;
}
if (!has_phis) { // No Phi users? Nothing merging?
for (uint i = 1; i < req()-1; i++) {
Node *if1 = in(i);
if( !if1 ) continue;
Node *iff = if1->in(0);
if( !iff || !iff->is_If() ) continue;
for( uint j=i+1; j<req(); j++ ) {
if( in(j) && in(j)->in(0) == iff &&
if1->Opcode() != in(j)->Opcode() ) {
// Add the IF Projections to the worklist. They (and the IF itself)
// will be eliminated if dead.
phase->is_IterGVN()->add_users_to_worklist(iff);
set_req(i, iff->in(0));// Skip around the useless IF diamond
set_req(j, NULL);
return this; // Record progress
}
}
}
}
}
// Remove TOP or NULL input paths. If only 1 input path remains, this Region
// degrades to a copy.
bool add_to_worklist = false;
int cnt = 0; // Count of values merging
DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
int del_it = 0; // The last input path we delete
// For all inputs...
for( uint i=1; i<req(); ++i ){// For all paths in
Node *n = in(i); // Get the input
if( n != NULL ) {
// Remove useless control copy inputs
if( n->is_Region() && n->as_Region()->is_copy() ) {
set_req(i, n->nonnull_req());
i--;
continue;
}
if( n->is_Proj() ) { // Remove useless rethrows
Node *call = n->in(0);
if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
set_req(i, call->in(0));
i--;
continue;
}
}
if( phase->type(n) == Type::TOP ) {
set_req(i, NULL); // Ignore TOP inputs
i--;
continue;
}
cnt++; // One more value merging
} else if (can_reshape) { // Else found dead path with DU info
PhaseIterGVN *igvn = phase->is_IterGVN();
del_req(i); // Yank path from self
del_it = i;
uint max = outcnt();
DUIterator j;
bool progress = true;
while(progress) { // Need to establish property over all users
progress = false;
for (j = outs(); has_out(j); j++) {
Node *n = out(j);
if( n->req() != req() && n->is_Phi() ) {
assert( n->in(0) == this, "" );
igvn->hash_delete(n); // Yank from hash before hacking edges
n->set_req_X(i,NULL,igvn);// Correct DU info
n->del_req(i); // Yank path from Phis
if( max != outcnt() ) {
progress = true;
j = refresh_out_pos(j);
max = outcnt();
}
}
}
}
add_to_worklist = true;
i--;
}
}
if (can_reshape && cnt == 1) {
// Is it dead loop?
// If it is LoopNopde it had 2 (+1 itself) inputs and
// one of them was cut. The loop is dead if it was EntryContol.
// Loop node may have only one input because entry path
// is removed in PhaseIdealLoop::Dominators().
assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
if (this->is_Loop() && (del_it == LoopNode::EntryControl ||
del_it == 0 && is_unreachable_region(phase)) ||
!this->is_Loop() && has_phis && is_unreachable_region(phase)) {
// Yes, the region will be removed during the next step below.
// Cut the backedge input and remove phis since no data paths left.
// We don't cut outputs to other nodes here since we need to put them
// on the worklist.
del_req(1);
cnt = 0;
assert( req() == 1, "no more inputs expected" );
uint max = outcnt();
bool progress = true;
Node *top = phase->C->top();
PhaseIterGVN *igvn = phase->is_IterGVN();
DUIterator j;
while(progress) {
progress = false;
for (j = outs(); has_out(j); j++) {
Node *n = out(j);
if( n->is_Phi() ) {
assert( igvn->eqv(n->in(0), this), "" );
assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
// Break dead loop data path.
// Eagerly replace phis with top to avoid phis copies generation.
igvn->replace_node(n, top);
if( max != outcnt() ) {
progress = true;
j = refresh_out_pos(j);
max = outcnt();
}
}
}
}
add_to_worklist = true;
}
}
if (add_to_worklist) {
phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
}
if( cnt <= 1 ) { // Only 1 path in?
set_req(0, NULL); // Null control input for region copy
if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
// No inputs or all inputs are NULL.
return NULL;
} else if (can_reshape) { // Optimization phase - remove the node
PhaseIterGVN *igvn = phase->is_IterGVN();
Node *parent_ctrl;
if( cnt == 0 ) {
assert( req() == 1, "no inputs expected" );
// During IGVN phase such region will be subsumed by TOP node
// so region's phis will have TOP as control node.
// Kill phis here to avoid it. PhiNode::is_copy() will be always false.
// Also set other user's input to top.
parent_ctrl = phase->C->top();
} else {
// The fallthrough case since we already checked dead loops above.
parent_ctrl = in(1);
assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
}
if (!add_to_worklist)
igvn->add_users_to_worklist(this); // Check for further allowed opts
for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
Node* n = last_out(i);
igvn->hash_delete(n); // Remove from worklist before modifying edges
if( n->is_Phi() ) { // Collapse all Phis
// Eagerly replace phis to avoid copies generation.
Node* in;
if( cnt == 0 ) {
assert( n->req() == 1, "No data inputs expected" );
in = parent_ctrl; // replaced by top
} else {
assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
in = n->in(1); // replaced by unique input
if( n->as_Phi()->is_unsafe_data_reference(in) )
in = phase->C->top(); // replaced by top
}
igvn->replace_node(n, in);
}
else if( n->is_Region() ) { // Update all incoming edges
assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
uint uses_found = 0;
for( uint k=1; k < n->req(); k++ ) {
if( n->in(k) == this ) {
n->set_req(k, parent_ctrl);
uses_found++;
}
}
if( uses_found > 1 ) { // (--i) done at the end of the loop.
i -= (uses_found - 1);
}
}
else {
assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
n->set_req(0, parent_ctrl);
}
#ifdef ASSERT
for( uint k=0; k < n->req(); k++ ) {
assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
}
#endif
}
// Remove the RegionNode itself from DefUse info
igvn->remove_dead_node(this);
return NULL;
}
return this; // Record progress
}
// If a Region flows into a Region, merge into one big happy merge.
if (can_reshape) {
Node *m = merge_region(this, phase);
if (m != NULL) return m;
}
// Check if this region is the root of a clipping idiom on floats
if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
// Check that only one use is a Phi and that it simplifies to two constants +
PhiNode* phi = has_unique_phi();
if (phi != NULL) { // One Phi user
// Check inputs to the Phi
ConNode *min;
ConNode *max;
Node *val;
uint min_idx;
uint max_idx;
uint val_idx;
if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
IfNode *top_if;
IfNode *bot_if;
if( check_if_clipping( this, bot_if, top_if ) ) {
// Control pattern checks, now verify compares
Node *top_in = NULL; // value being compared against
Node *bot_in = NULL;
if( check_compare_clipping( true, bot_if, min, bot_in ) &&
check_compare_clipping( false, top_if, max, top_in ) ) {
if( bot_in == top_in ) {
PhaseIterGVN *gvn = phase->is_IterGVN();
assert( gvn != NULL, "Only had DefUse info in IterGVN");
// Only remaining check is that bot_in == top_in == (Phi's val + mods)
// Check for the ConvF2INode
ConvF2INode *convf2i;
if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
convf2i->in(1) == bot_in ) {
// Matched pattern, including LShiftI; RShiftI, replace with integer compares
// max test
Node *cmp = gvn->register_new_node_with_optimizer(new (phase->C) CmpINode( convf2i, min ));
Node *boo = gvn->register_new_node_with_optimizer(new (phase->C) BoolNode( cmp, BoolTest::lt ));
IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C) IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
Node *if_min= gvn->register_new_node_with_optimizer(new (phase->C) IfTrueNode (iff));
Node *ifF = gvn->register_new_node_with_optimizer(new (phase->C) IfFalseNode(iff));
// min test
cmp = gvn->register_new_node_with_optimizer(new (phase->C) CmpINode( convf2i, max ));
boo = gvn->register_new_node_with_optimizer(new (phase->C) BoolNode( cmp, BoolTest::gt ));
iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C) IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
Node *if_max= gvn->register_new_node_with_optimizer(new (phase->C) IfTrueNode (iff));
ifF = gvn->register_new_node_with_optimizer(new (phase->C) IfFalseNode(iff));
// update input edges to region node
set_req_X( min_idx, if_min, gvn );
set_req_X( max_idx, if_max, gvn );
set_req_X( val_idx, ifF, gvn );
// remove unnecessary 'LShiftI; RShiftI' idiom
gvn->hash_delete(phi);
phi->set_req_X( val_idx, convf2i, gvn );
gvn->hash_find_insert(phi);
// Return transformed region node
return this;
}
}
}
}
}
}
}
return NULL;
}
const RegMask &RegionNode::out_RegMask() const {
return RegMask::Empty;
}
// Find the one non-null required input. RegionNode only
Node *Node::nonnull_req() const {
assert( is_Region(), "" );
for( uint i = 1; i < _cnt; i++ )
if( in(i) )
return in(i);
ShouldNotReachHere();
return NULL;
}
//=============================================================================
// note that these functions assume that the _adr_type field is flattened
uint PhiNode::hash() const {
const Type* at = _adr_type;
return TypeNode::hash() + (at ? at->hash() : 0);
}
uint PhiNode::cmp( const Node &n ) const {
return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
}
static inline
const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
if (at == NULL || at == TypePtr::BOTTOM) return at;
return Compile::current()->alias_type(at)->adr_type();
}
//----------------------------make---------------------------------------------
// create a new phi with edges matching r and set (initially) to x
PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
uint preds = r->req(); // Number of predecessor paths
assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
PhiNode* p = new (Compile::current()) PhiNode(r, t, at);
for (uint j = 1; j < preds; j++) {
// Fill in all inputs, except those which the region does not yet have
if (r->in(j) != NULL)
p->init_req(j, x);
}
return p;
}
PhiNode* PhiNode::make(Node* r, Node* x) {
const Type* t = x->bottom_type();
const TypePtr* at = NULL;
if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
return make(r, x, t, at);
}
PhiNode* PhiNode::make_blank(Node* r, Node* x) {
const Type* t = x->bottom_type();
const TypePtr* at = NULL;
if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
return new (Compile::current()) PhiNode(r, t, at);
}
//------------------------slice_memory-----------------------------------------
// create a new phi with narrowed memory type
PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
PhiNode* mem = (PhiNode*) clone();
*(const TypePtr**)&mem->_adr_type = adr_type;
// convert self-loops, or else we get a bad graph
for (uint i = 1; i < req(); i++) {
if ((const Node*)in(i) == this) mem->set_req(i, mem);
}
mem->verify_adr_type();
return mem;
}
//------------------------split_out_instance-----------------------------------
// Split out an instance type from a bottom phi.
PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
const TypeOopPtr *t_oop = at->isa_oopptr();
assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
const TypePtr *t = adr_type();
assert(type() == Type::MEMORY &&
(t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
t->is_oopptr()->cast_to_exactness(true)
->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
"bottom or raw memory required");
// Check if an appropriate node already exists.
Node *region = in(0);
for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
Node* use = region->fast_out(k);
if( use->is_Phi()) {
PhiNode *phi2 = use->as_Phi();
if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
return phi2;
}
}
}
Compile *C = igvn->C;
Arena *a = Thread::current()->resource_area();
Node_Array node_map = new Node_Array(a);
Node_Stack stack(a, C->unique() >> 4);
PhiNode *nphi = slice_memory(at);
igvn->register_new_node_with_optimizer( nphi );
node_map.map(_idx, nphi);
stack.push((Node *)this, 1);
while(!stack.is_empty()) {
PhiNode *ophi = stack.node()->as_Phi();
uint i = stack.index();
assert(i >= 1, "not control edge");
stack.pop();
nphi = node_map[ophi->_idx]->as_Phi();
for (; i < ophi->req(); i++) {
Node *in = ophi->in(i);
if (in == NULL || igvn->type(in) == Type::TOP)
continue;
Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
opt = node_map[optphi->_idx];
if (opt == NULL) {
stack.push(ophi, i);
nphi = optphi->slice_memory(at);
igvn->register_new_node_with_optimizer( nphi );
node_map.map(optphi->_idx, nphi);
ophi = optphi;
i = 0; // will get incremented at top of loop
continue;
}
}
nphi->set_req(i, opt);
}
}
return nphi;
}
//------------------------verify_adr_type--------------------------------------
#ifdef ASSERT
void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
if (visited.test_set(_idx)) return; //already visited
// recheck constructor invariants:
verify_adr_type(false);
// recheck local phi/phi consistency:
assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
"adr_type must be consistent across phi nest");
// walk around
for (uint i = 1; i < req(); i++) {
Node* n = in(i);
if (n == NULL) continue;
const Node* np = in(i);
if (np->is_Phi()) {
np->as_Phi()->verify_adr_type(visited, at);
} else if (n->bottom_type() == Type::TOP
|| (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
// ignore top inputs
} else {
const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
// recheck phi/non-phi consistency at leaves:
assert((nat != NULL) == (at != NULL), "");
assert(nat == at || nat == TypePtr::BOTTOM,
"adr_type must be consistent at leaves of phi nest");
}
}
}
// Verify a whole nest of phis rooted at this one.
void PhiNode::verify_adr_type(bool recursive) const {
if (is_error_reported()) return; // muzzle asserts when debugging an error
if (Node::in_dump()) return; // muzzle asserts when printing
assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
if (!VerifyAliases) return; // verify thoroughly only if requested
assert(_adr_type == flatten_phi_adr_type(_adr_type),
"Phi::adr_type must be pre-normalized");
if (recursive) {
VectorSet visited(Thread::current()->resource_area());
verify_adr_type(visited, _adr_type);
}
}
#endif
//------------------------------Value------------------------------------------
// Compute the type of the PhiNode
const Type *PhiNode::Value( PhaseTransform *phase ) const {
Node *r = in(0); // RegionNode
if( !r ) // Copy or dead
return in(1) ? phase->type(in(1)) : Type::TOP;
// Note: During parsing, phis are often transformed before their regions.
// This means we have to use type_or_null to defend against untyped regions.
if( phase->type_or_null(r) == Type::TOP ) // Dead code?
return Type::TOP;
// Check for trip-counted loop. If so, be smarter.
CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
if( l && l->can_be_counted_loop(phase) &&
((const Node*)l->phi() == this) ) { // Trip counted loop!
// protect against init_trip() or limit() returning NULL
const Node *init = l->init_trip();
const Node *limit = l->limit();
if( init != NULL && limit != NULL && l->stride_is_con() ) {
const TypeInt *lo = init ->bottom_type()->isa_int();
const TypeInt *hi = limit->bottom_type()->isa_int();
if( lo && hi ) { // Dying loops might have TOP here
int stride = l->stride_con();
if( stride < 0 ) { // Down-counter loop
const TypeInt *tmp = lo; lo = hi; hi = tmp;
stride = -stride;
}
if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-(
return TypeInt::make(lo->_lo,hi->_hi,3);
}
}
}
// Until we have harmony between classes and interfaces in the type
// lattice, we must tread carefully around phis which implicitly
// convert the one to the other.
const TypePtr* ttp = _type->make_ptr();
const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
bool is_intf = false;
if (ttip != NULL) {
ciKlass* k = ttip->klass();
if (k->is_loaded() && k->is_interface())
is_intf = true;
}
if (ttkp != NULL) {
ciKlass* k = ttkp->klass();
if (k->is_loaded() && k->is_interface())
is_intf = true;
}
// Default case: merge all inputs
const Type *t = Type::TOP; // Merged type starting value
for (uint i = 1; i < req(); ++i) {// For all paths in
// Reachable control path?
if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
const Type* ti = phase->type(in(i));
// We assume that each input of an interface-valued Phi is a true
// subtype of that interface. This might not be true of the meet
// of all the input types. The lattice is not distributive in
// such cases. Ward off asserts in type.cpp by refusing to do
// meets between interfaces and proper classes.
const TypePtr* tip = ti->make_ptr();
const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
if (tiip) {
bool ti_is_intf = false;
ciKlass* k = tiip->klass();
if (k->is_loaded() && k->is_interface())
ti_is_intf = true;
if (is_intf != ti_is_intf)
{ t = _type; break; }
}
t = t->meet(ti);
}
}
// The worst-case type (from ciTypeFlow) should be consistent with "t".
// That is, we expect that "t->higher_equal(_type)" holds true.
// There are various exceptions:
// - Inputs which are phis might in fact be widened unnecessarily.
// For example, an input might be a widened int while the phi is a short.
// - Inputs might be BotPtrs but this phi is dependent on a null check,
// and postCCP has removed the cast which encodes the result of the check.
// - The type of this phi is an interface, and the inputs are classes.
// - Value calls on inputs might produce fuzzy results.
// (Occurrences of this case suggest improvements to Value methods.)
//
// It is not possible to see Type::BOTTOM values as phi inputs,
// because the ciTypeFlow pre-pass produces verifier-quality types.
const Type* ft = t->filter(_type); // Worst case type
#ifdef ASSERT
// The following logic has been moved into TypeOopPtr::filter.
const Type* jt = t->join(_type);
if( jt->empty() ) { // Emptied out???
// Check for evil case of 't' being a class and '_type' expecting an
// interface. This can happen because the bytecodes do not contain
// enough type info to distinguish a Java-level interface variable
// from a Java-level object variable. If we meet 2 classes which
// both implement interface I, but their meet is at 'j/l/O' which
// doesn't implement I, we have no way to tell if the result should
// be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
// into a Phi which "knows" it's an Interface type we'll have to
// uplift the type.
if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() )
{ assert(ft == _type, ""); } // Uplift to interface
else if( !t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface() )
{ assert(ft == _type, ""); } // Uplift to interface
// Otherwise it's something stupid like non-overlapping int ranges
// found on dying counted loops.
else
{ assert(ft == Type::TOP, ""); } // Canonical empty value
}
else {
// If we have an interface-typed Phi and we narrow to a class type, the join
// should report back the class. However, if we have a J/L/Object
// class-typed Phi and an interface flows in, it's possible that the meet &
// join report an interface back out. This isn't possible but happens
// because the type system doesn't interact well with interfaces.
const TypePtr *jtp = jt->make_ptr();
const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
if( jtip && ttip ) {
if( jtip->is_loaded() && jtip->klass()->is_interface() &&
ttip->is_loaded() && !ttip->klass()->is_interface() ) {
// Happens in a CTW of rt.jar, 320-341, no extra flags
assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
jt = ft;
}
}
if( jtkp && ttkp ) {
if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
!jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
ft->isa_narrowoop() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
jt = ft;
}
}
if (jt != ft && jt->base() == ft->base()) {
if (jt->isa_int() &&
jt->is_int()->_lo == ft->is_int()->_lo &&
jt->is_int()->_hi == ft->is_int()->_hi)
jt = ft;
if (jt->isa_long() &&
jt->is_long()->_lo == ft->is_long()->_lo &&
jt->is_long()->_hi == ft->is_long()->_hi)
jt = ft;
}
if (jt != ft) {
tty->print("merge type: "); t->dump(); tty->cr();
tty->print("kill type: "); _type->dump(); tty->cr();
tty->print("join type: "); jt->dump(); tty->cr();
tty->print("filter type: "); ft->dump(); tty->cr();
}
assert(jt == ft, "");
}
#endif //ASSERT
// Deal with conversion problems found in data loops.
ft = phase->saturate(ft, phase->type_or_null(this), _type);
return ft;
}
//------------------------------is_diamond_phi---------------------------------
// Does this Phi represent a simple well-shaped diamond merge? Return the
// index of the true path or 0 otherwise.
// If check_control_only is true, do not inspect the If node at the
// top, and return -1 (not an edge number) on success.
int PhiNode::is_diamond_phi(bool check_control_only) const {
// Check for a 2-path merge
Node *region = in(0);
if( !region ) return 0;
if( region->req() != 3 ) return 0;
if( req() != 3 ) return 0;
// Check that both paths come from the same If
Node *ifp1 = region->in(1);
Node *ifp2 = region->in(2);
if( !ifp1 || !ifp2 ) return 0;
Node *iff = ifp1->in(0);
if( !iff || !iff->is_If() ) return 0;
if( iff != ifp2->in(0) ) return 0;
if (check_control_only) return -1;
// Check for a proper bool/cmp
const Node *b = iff->in(1);
if( !b->is_Bool() ) return 0;
const Node *cmp = b->in(1);
if( !cmp->is_Cmp() ) return 0;
// Check for branching opposite expected
if( ifp2->Opcode() == Op_IfTrue ) {
assert( ifp1->Opcode() == Op_IfFalse, "" );
return 2;
} else {
assert( ifp1->Opcode() == Op_IfTrue, "" );
return 1;
}
}
//----------------------------check_cmove_id-----------------------------------
// Check for CMove'ing a constant after comparing against the constant.
// Happens all the time now, since if we compare equality vs a constant in
// the parser, we "know" the variable is constant on one path and we force
// it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
// conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
// general in that we don't need constants. Since CMove's are only inserted
// in very special circumstances, we do it here on generic Phi's.
Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
assert(true_path !=0, "only diamond shape graph expected");
// is_diamond_phi() has guaranteed the correctness of the nodes sequence:
// phi->region->if_proj->ifnode->bool->cmp
Node* region = in(0);
Node* iff = region->in(1)->in(0);
BoolNode* b = iff->in(1)->as_Bool();
Node* cmp = b->in(1);
Node* tval = in(true_path);
Node* fval = in(3-true_path);
Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
if (id == NULL)
return NULL;
// Either value might be a cast that depends on a branch of 'iff'.
// Since the 'id' value will float free of the diamond, either
// decast or return failure.
Node* ctl = id->in(0);
if (ctl != NULL && ctl->in(0) == iff) {
if (id->is_ConstraintCast()) {
return id->in(1);
} else {
// Don't know how to disentangle this value.
return NULL;
}
}
return id;
}
//------------------------------Identity---------------------------------------
// Check for Region being Identity.
Node *PhiNode::Identity( PhaseTransform *phase ) {
// Check for no merging going on
// (There used to be special-case code here when this->region->is_Loop.
// It would check for a tributary phi on the backedge that the main phi
// trivially, perhaps with a single cast. The unique_input method
// does all this and more, by reducing such tributaries to 'this'.)
Node* uin = unique_input(phase);
if (uin != NULL) {
return uin;
}
int true_path = is_diamond_phi();
if (true_path != 0) {
Node* id = is_cmove_id(phase, true_path);
if (id != NULL) return id;
}
return this; // No identity
}
//-----------------------------unique_input------------------------------------
// Find the unique value, discounting top, self-loops, and casts.
// Return top if there are no inputs, and self if there are multiple.
Node* PhiNode::unique_input(PhaseTransform* phase) {
// 1) One unique direct input, or
// 2) some of the inputs have an intervening ConstraintCast and
// the type of input is the same or sharper (more specific)
// than the phi's type.
// 3) an input is a self loop
//
// 1) input or 2) input or 3) input __
// / \ / \ \ / \
// \ / | cast phi cast
// phi \ / / \ /
// phi / --
Node* r = in(0); // RegionNode
if (r == NULL) return in(1); // Already degraded to a Copy
Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed)
Node* direct_input = NULL; // The unique direct input
for (uint i = 1, cnt = req(); i < cnt; ++i) {
Node* rc = r->in(i);
if (rc == NULL || phase->type(rc) == Type::TOP)
continue; // ignore unreachable control path
Node* n = in(i);
if (n == NULL)
continue;
Node* un = n->uncast();
if (un == NULL || un == this || phase->type(un) == Type::TOP) {
continue; // ignore if top, or in(i) and "this" are in a data cycle
}
// Check for a unique uncasted input
if (uncasted_input == NULL) {
uncasted_input = un;
} else if (uncasted_input != un) {
uncasted_input = NodeSentinel; // no unique uncasted input
}
// Check for a unique direct input
if (direct_input == NULL) {
direct_input = n;
} else if (direct_input != n) {
direct_input = NodeSentinel; // no unique direct input
}
}
if (direct_input == NULL) {
return phase->C->top(); // no inputs
}
assert(uncasted_input != NULL,"");
if (direct_input != NodeSentinel) {
return direct_input; // one unique direct input
}
if (uncasted_input != NodeSentinel &&
phase->type(uncasted_input)->higher_equal(type())) {
return uncasted_input; // one unique uncasted input
}
// Nothing.
return NULL;
}
//------------------------------is_x2logic-------------------------------------
// Check for simple convert-to-boolean pattern
// If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
// Convert Phi to an ConvIB.
static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
assert(true_path !=0, "only diamond shape graph expected");
// Convert the true/false index into an expected 0/1 return.
// Map 2->0 and 1->1.
int flipped = 2-true_path;
// is_diamond_phi() has guaranteed the correctness of the nodes sequence:
// phi->region->if_proj->ifnode->bool->cmp
Node *region = phi->in(0);
Node *iff = region->in(1)->in(0);
BoolNode *b = (BoolNode*)iff->in(1);
const CmpNode *cmp = (CmpNode*)b->in(1);
Node *zero = phi->in(1);
Node *one = phi->in(2);
const Type *tzero = phase->type( zero );
const Type *tone = phase->type( one );
// Check for compare vs 0
const Type *tcmp = phase->type(cmp->in(2));
if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
// Allow cmp-vs-1 if the other input is bounded by 0-1
if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
return NULL;
flipped = 1-flipped; // Test is vs 1 instead of 0!
}
// Check for setting zero/one opposite expected
if( tzero == TypeInt::ZERO ) {
if( tone == TypeInt::ONE ) {
} else return NULL;
} else if( tzero == TypeInt::ONE ) {
if( tone == TypeInt::ZERO ) {
flipped = 1-flipped;
} else return NULL;
} else return NULL;
// Check for boolean test backwards
if( b->_test._test == BoolTest::ne ) {
} else if( b->_test._test == BoolTest::eq ) {
flipped = 1-flipped;
} else return NULL;
// Build int->bool conversion
Node *n = new (phase->C) Conv2BNode( cmp->in(1) );
if( flipped )
n = new (phase->C) XorINode( phase->transform(n), phase->intcon(1) );
return n;
}
//------------------------------is_cond_add------------------------------------
// Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
// To be profitable the control flow has to disappear; there can be no other
// values merging here. We replace the test-and-branch with:
// "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
// moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
// Then convert Y to 0-or-Y and finally add.
// This is a key transform for SpecJava _201_compress.
static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
assert(true_path !=0, "only diamond shape graph expected");
// is_diamond_phi() has guaranteed the correctness of the nodes sequence:
// phi->region->if_proj->ifnode->bool->cmp
RegionNode *region = (RegionNode*)phi->in(0);
Node *iff = region->in(1)->in(0);
BoolNode* b = iff->in(1)->as_Bool();
const CmpNode *cmp = (CmpNode*)b->in(1);
// Make sure only merging this one phi here
if (region->has_unique_phi() != phi) return NULL;
// Make sure each arm of the diamond has exactly one output, which we assume
// is the region. Otherwise, the control flow won't disappear.
if (region->in(1)->outcnt() != 1) return NULL;
if (region->in(2)->outcnt() != 1) return NULL;
// Check for "(P < Q)" of type signed int
if (b->_test._test != BoolTest::lt) return NULL;
if (cmp->Opcode() != Op_CmpI) return NULL;
Node *p = cmp->in(1);
Node *q = cmp->in(2);
Node *n1 = phi->in( true_path);
Node *n2 = phi->in(3-true_path);
int op = n1->Opcode();
if( op != Op_AddI // Need zero as additive identity
/*&&op != Op_SubI &&
op != Op_AddP &&
op != Op_XorI &&
op != Op_OrI*/ )
return NULL;
Node *x = n2;
Node *y = NULL;
if( x == n1->in(1) ) {
y = n1->in(2);
} else if( x == n1->in(2) ) {
y = n1->in(1);
} else return NULL;
// Not so profitable if compare and add are constants
if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
return NULL;
Node *cmplt = phase->transform( new (phase->C) CmpLTMaskNode(p,q) );
Node *j_and = phase->transform( new (phase->C) AndINode(cmplt,y) );
return new (phase->C) AddINode(j_and,x);
}
//------------------------------is_absolute------------------------------------
// Check for absolute value.
static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
assert(true_path !=0, "only diamond shape graph expected");
int cmp_zero_idx = 0; // Index of compare input where to look for zero
int phi_x_idx = 0; // Index of phi input where to find naked x
// ABS ends with the merge of 2 control flow paths.
// Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
int false_path = 3 - true_path;
// is_diamond_phi() has guaranteed the correctness of the nodes sequence:
// phi->region->if_proj->ifnode->bool->cmp
BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
// Check bool sense
switch( bol->_test._test ) {
case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
default: return NULL; break;
}
// Test is next
Node *cmp = bol->in(1);
const Type *tzero = NULL;
switch( cmp->Opcode() ) {
case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
default: return NULL;
}
// Find zero input of compare; the other input is being abs'd
Node *x = NULL;
bool flip = false;
if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
x = cmp->in(3 - cmp_zero_idx);
} else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
// The test is inverted, we should invert the result...
x = cmp->in(cmp_zero_idx);
flip = true;
} else {
return NULL;
}
// Next get the 2 pieces being selected, one is the original value
// and the other is the negated value.
if( phi_root->in(phi_x_idx) != x ) return NULL;
// Check other phi input for subtract node
Node *sub = phi_root->in(3 - phi_x_idx);
// Allow only Sub(0,X) and fail out for all others; Neg is not OK
if( tzero == TypeF::ZERO ) {
if( sub->Opcode() != Op_SubF ||
sub->in(2) != x ||
phase->type(sub->in(1)) != tzero ) return NULL;
x = new (phase->C) AbsFNode(x);
if (flip) {
x = new (phase->C) SubFNode(sub->in(1), phase->transform(x));
}
} else {
if( sub->Opcode() != Op_SubD ||
sub->in(2) != x ||
phase->type(sub->in(1)) != tzero ) return NULL;
x = new (phase->C) AbsDNode(x);
if (flip) {
x = new (phase->C) SubDNode(sub->in(1), phase->transform(x));
}
}
return x;
}
//------------------------------split_once-------------------------------------
// Helper for split_flow_path
static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
igvn->hash_delete(n); // Remove from hash before hacking edges
uint j = 1;
for (uint i = phi->req()-1; i > 0; i--) {
if (phi->in(i) == val) { // Found a path with val?
// Add to NEW Region/Phi, no DU info
newn->set_req( j++, n->in(i) );
// Remove from OLD Region/Phi
n->del_req(i);
}
}
// Register the new node but do not transform it. Cannot transform until the
// entire Region/Phi conglomerate has been hacked as a single huge transform.
igvn->register_new_node_with_optimizer( newn );
// Now I can point to the new node.
n->add_req(newn);
igvn->_worklist.push(n);
}
//------------------------------split_flow_path--------------------------------
// Check for merging identical values and split flow paths
static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
BasicType bt = phi->type()->basic_type();
if( bt == T_ILLEGAL || type2size[bt] <= 0 )
return NULL; // Bail out on funny non-value stuff
if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
return NULL; // third unequal input to be worth doing
// Scan for a constant
uint i;
for( i = 1; i < phi->req()-1; i++ ) {
Node *n = phi->in(i);
if( !n ) return NULL;
if( phase->type(n) == Type::TOP ) return NULL;
if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
break;
}
if( i >= phi->req() ) // Only split for constants
return NULL;
Node *val = phi->in(i); // Constant to split for
uint hit = 0; // Number of times it occurs
Node *r = phi->region();
for( ; i < phi->req(); i++ ){ // Count occurrences of constant
Node *n = phi->in(i);
if( !n ) return NULL;
if( phase->type(n) == Type::TOP ) return NULL;
if( phi->in(i) == val ) {
hit++;
if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
return NULL; // don't split loop entry path
}
}
}
if( hit <= 1 || // Make sure we find 2 or more
hit == phi->req()-1 ) // and not ALL the same value
return NULL;
// Now start splitting out the flow paths that merge the same value.
// Split first the RegionNode.
PhaseIterGVN *igvn = phase->is_IterGVN();
RegionNode *newr = new (phase->C) RegionNode(hit+1);
split_once(igvn, phi, val, r, newr);
// Now split all other Phis than this one
for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
Node* phi2 = r->fast_out(k);
if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
PhiNode *newphi = PhiNode::make_blank(newr, phi2);
split_once(igvn, phi, val, phi2, newphi);
}
}
// Clean up this guy
igvn->hash_delete(phi);
for( i = phi->req()-1; i > 0; i-- ) {
if( phi->in(i) == val ) {
phi->del_req(i);
}
}
phi->add_req(val);
return phi;
}
//=============================================================================
//------------------------------simple_data_loop_check-------------------------
// Try to determining if the phi node in a simple safe/unsafe data loop.
// Returns:
// enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
// Safe - safe case when the phi and it's inputs reference only safe data
// nodes;
// Unsafe - the phi and it's inputs reference unsafe data nodes but there
// is no reference back to the phi - need a graph walk
// to determine if it is in a loop;
// UnsafeLoop - unsafe case when the phi references itself directly or through
// unsafe data node.
// Note: a safe data node is a node which could/never reference itself during
// GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
// I mark Phi nodes as safe node not only because they can reference itself
// but also to prevent mistaking the fallthrough case inside an outer loop
// as dead loop when the phi references itselfs through an other phi.
PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
// It is unsafe loop if the phi node references itself directly.
if (in == (Node*)this)
return UnsafeLoop; // Unsafe loop
// Unsafe loop if the phi node references itself through an unsafe data node.
// Exclude cases with null inputs or data nodes which could reference
// itself (safe for dead loops).
if (in != NULL && !in->is_dead_loop_safe()) {
// Check inputs of phi's inputs also.
// It is much less expensive then full graph walk.
uint cnt = in->req();
uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
for (; i < cnt; ++i) {
Node* m = in->in(i);
if (m == (Node*)this)
return UnsafeLoop; // Unsafe loop
if (m != NULL && !m->is_dead_loop_safe()) {
// Check the most common case (about 30% of all cases):
// phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
if (m1 == (Node*)this)
return UnsafeLoop; // Unsafe loop
if (m1 != NULL && m1 == m->in(2) &&
m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
continue; // Safe case
}
// The phi references an unsafe node - need full analysis.
return Unsafe;
}
}
}
return Safe; // Safe case - we can optimize the phi node.
}
//------------------------------is_unsafe_data_reference-----------------------
// If phi can be reached through the data input - it is data loop.
bool PhiNode::is_unsafe_data_reference(Node *in) const {
assert(req() > 1, "");
// First, check simple cases when phi references itself directly or
// through an other node.
LoopSafety safety = simple_data_loop_check(in);
if (safety == UnsafeLoop)
return true; // phi references itself - unsafe loop
else if (safety == Safe)
return false; // Safe case - phi could be replaced with the unique input.
// Unsafe case when we should go through data graph to determine
// if the phi references itself.
ResourceMark rm;
Arena *a = Thread::current()->resource_area();
Node_List nstack(a);
VectorSet visited(a);
nstack.push(in); // Start with unique input.
visited.set(in->_idx);
while (nstack.size() != 0) {
Node* n = nstack.pop();
uint cnt = n->req();
uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
for (; i < cnt; i++) {
Node* m = n->in(i);
if (m == (Node*)this) {
return true; // Data loop
}
if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
if (!visited.test_set(m->_idx))
nstack.push(m);
}
}
}
return false; // The phi is not reachable from its inputs
}
//------------------------------Ideal------------------------------------------
// Return a node which is more "ideal" than the current node. Must preserve
// the CFG, but we can still strip out dead paths.
Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
// The next should never happen after 6297035 fix.
if( is_copy() ) // Already degraded to a Copy ?
return NULL; // No change
Node *r = in(0); // RegionNode
assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
// Note: During parsing, phis are often transformed before their regions.
// This means we have to use type_or_null to defend against untyped regions.
if( phase->type_or_null(r) == Type::TOP ) // Dead code?
return NULL; // No change
Node *top = phase->C->top();
bool new_phi = (outcnt() == 0); // transforming new Phi
// No change for igvn if new phi is not hooked
if (new_phi && can_reshape)
return NULL;
// The are 2 situations when only one valid phi's input is left
// (in addition to Region input).
// One: region is not loop - replace phi with this input.
// Two: region is loop - replace phi with top since this data path is dead
// and we need to break the dead data loop.
Node* progress = NULL; // Record if any progress made
for( uint j = 1; j < req(); ++j ){ // For all paths in
// Check unreachable control paths
Node* rc = r->in(j);
Node* n = in(j); // Get the input
if (rc == NULL || phase->type(rc) == Type::TOP) {
if (n != top) { // Not already top?
PhaseIterGVN *igvn = phase->is_IterGVN();
if (can_reshape && igvn != NULL) {
igvn->_worklist.push(r);
}
set_req(j, top); // Nuke it down
progress = this; // Record progress
}
}
}
if (can_reshape && outcnt() == 0) {
// set_req() above may kill outputs if Phi is referenced
// only by itself on the dead (top) control path.
return top;
}
Node* uin = unique_input(phase);
if (uin == top) { // Simplest case: no alive inputs.
if (can_reshape) // IGVN transformation
return top;
else
return NULL; // Identity will return TOP
} else if (uin != NULL) {
// Only one not-NULL unique input path is left.
// Determine if this input is backedge of a loop.
// (Skip new phis which have no uses and dead regions).
if (outcnt() > 0 && r->in(0) != NULL) {
// First, take the short cut when we know it is a loop and
// the EntryControl data path is dead.
// Loop node may have only one input because entry path
// is removed in PhaseIdealLoop::Dominators().
assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
bool is_loop = (r->is_Loop() && r->req() == 3);
// Then, check if there is a data loop when phi references itself directly
// or through other data nodes.
if (is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl)) ||
!is_loop && is_unsafe_data_reference(uin)) {
// Break this data loop to avoid creation of a dead loop.
if (can_reshape) {
return top;
} else {
// We can't return top if we are in Parse phase - cut inputs only
// let Identity to handle the case.
replace_edge(uin, top);
return NULL;
}
}
}
// One unique input.
debug_only(Node* ident = Identity(phase));
// The unique input must eventually be detected by the Identity call.
#ifdef ASSERT
if (ident != uin && !ident->is_top()) {
// print this output before failing assert
r->dump(3);
this->dump(3);
ident->dump();
uin->dump();
}
#endif
assert(ident == uin || ident->is_top(), "Identity must clean this up");
return NULL;
}
Node* opt = NULL;
int true_path = is_diamond_phi();
if( true_path != 0 ) {
// Check for CMove'ing identity. If it would be unsafe,
// handle it here. In the safe case, let Identity handle it.
Node* unsafe_id = is_cmove_id(phase, true_path);
if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
opt = unsafe_id;
// Check for simple convert-to-boolean pattern
if( opt == NULL )
opt = is_x2logic(phase, this, true_path);
// Check for absolute value
if( opt == NULL )
opt = is_absolute(phase, this, true_path);
// Check for conditional add
if( opt == NULL && can_reshape )
opt = is_cond_add(phase, this, true_path);
// These 4 optimizations could subsume the phi:
// have to check for a dead data loop creation.
if( opt != NULL ) {
if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
// Found dead loop.
if( can_reshape )
return top;
// We can't return top if we are in Parse phase - cut inputs only
// to stop further optimizations for this phi. Identity will return TOP.
assert(req() == 3, "only diamond merge phi here");
set_req(1, top);
set_req(2, top);
return NULL;
} else {
return opt;
}
}
}
// Check for merging identical values and split flow paths
if (can_reshape) {
opt = split_flow_path(phase, this);
// This optimization only modifies phi - don't need to check for dead loop.
assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
if (opt != NULL) return opt;
}
if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
// Try to undo Phi of AddP:
// (Phi (AddP base base y) (AddP base2 base2 y))
// becomes:
// newbase := (Phi base base2)
// (AddP newbase newbase y)
//
// This occurs as a result of unsuccessful split_thru_phi and
// interferes with taking advantage of addressing modes. See the
// clone_shift_expressions code in matcher.cpp
Node* addp = in(1);
const Type* type = addp->in(AddPNode::Base)->bottom_type();
Node* y = addp->in(AddPNode::Offset);
if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
// make sure that all the inputs are similar to the first one,
// i.e. AddP with base == address and same offset as first AddP
bool doit = true;
for (uint i = 2; i < req(); i++) {
if (in(i) == NULL ||
in(i)->Opcode() != Op_AddP ||
in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
in(i)->in(AddPNode::Offset) != y) {
doit = false;
break;
}
// Accumulate type for resulting Phi
type = type->meet(in(i)->in(AddPNode::Base)->bottom_type());
}
Node* base = NULL;
if (doit) {
// Check for neighboring AddP nodes in a tree.
// If they have a base, use that it.
for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
Node* u = this->fast_out(k);
if (u->is_AddP()) {
Node* base2 = u->in(AddPNode::Base);
if (base2 != NULL && !base2->is_top()) {
if (base == NULL)
base = base2;
else if (base != base2)
{ doit = false; break; }
}
}
}
}
if (doit) {
if (base == NULL) {
base = new (phase->C) PhiNode(in(0), type, NULL);
for (uint i = 1; i < req(); i++) {
base->init_req(i, in(i)->in(AddPNode::Base));
}
phase->is_IterGVN()->register_new_node_with_optimizer(base);
}
return new (phase->C) AddPNode(base, base, y);
}
}
}
// Split phis through memory merges, so that the memory merges will go away.
// Piggy-back this transformation on the search for a unique input....
// It will be as if the merged memory is the unique value of the phi.
// (Do not attempt this optimization unless parsing is complete.
// It would make the parser's memory-merge logic sick.)
// (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
if (progress == NULL && can_reshape && type() == Type::MEMORY) {
// see if this phi should be sliced
uint merge_width = 0;
bool saw_self = false;
for( uint i=1; i<req(); ++i ) {// For all paths in
Node *ii = in(i);
if (ii->is_MergeMem()) {
MergeMemNode* n = ii->as_MergeMem();
merge_width = MAX2(merge_width, n->req());
saw_self = saw_self || phase->eqv(n->base_memory(), this);
}
}
// This restriction is temporarily necessary to ensure termination:
if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
if (merge_width > Compile::AliasIdxRaw) {
// found at least one non-empty MergeMem
const TypePtr* at = adr_type();
if (at != TypePtr::BOTTOM) {
// Patch the existing phi to select an input from the merge:
// Phi:AT1(...MergeMem(m0, m1, m2)...) into
// Phi:AT1(...m1...)
int alias_idx = phase->C->get_alias_index(at);
for (uint i=1; i<req(); ++i) {
Node *ii = in(i);
if (ii->is_MergeMem()) {
MergeMemNode* n = ii->as_MergeMem();
// compress paths and change unreachable cycles to TOP
// If not, we can update the input infinitely along a MergeMem cycle
// Equivalent code is in MemNode::Ideal_common
Node *m = phase->transform(n);
if (outcnt() == 0) { // Above transform() may kill us!
return top;
}
// If transformed to a MergeMem, get the desired slice
// Otherwise the returned node represents memory for every slice
Node *new_mem = (m->is_MergeMem()) ?
m->as_MergeMem()->memory_at(alias_idx) : m;
// Update input if it is progress over what we have now
if (new_mem != ii) {
set_req(i, new_mem);
progress = this;
}
}
}
} else {
// We know that at least one MergeMem->base_memory() == this
// (saw_self == true). If all other inputs also references this phi
// (directly or through data nodes) - it is dead loop.
bool saw_safe_input = false;
for (uint j = 1; j < req(); ++j) {
Node *n = in(j);
if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
continue; // skip known cases
if (!is_unsafe_data_reference(n)) {
saw_safe_input = true; // found safe input
break;
}
}
if (!saw_safe_input)
return top; // all inputs reference back to this phi - dead loop
// Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
// MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
PhaseIterGVN *igvn = phase->is_IterGVN();
Node* hook = new (phase->C) Node(1);
PhiNode* new_base = (PhiNode*) clone();
// Must eagerly register phis, since they participate in loops.
if (igvn) {
igvn->register_new_node_with_optimizer(new_base);
hook->add_req(new_base);
}
MergeMemNode* result = MergeMemNode::make(phase->C, new_base);
for (uint i = 1; i < req(); ++i) {
Node *ii = in(i);
if (ii->is_MergeMem()) {
MergeMemNode* n = ii->as_MergeMem();
for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
// If we have not seen this slice yet, make a phi for it.
bool made_new_phi = false;
if (mms.is_empty()) {
Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
made_new_phi = true;
if (igvn) {
igvn->register_new_node_with_optimizer(new_phi);
hook->add_req(new_phi);
}
mms.set_memory(new_phi);
}
Node* phi = mms.memory();
assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
phi->set_req(i, mms.memory2());
}
}
}
// Distribute all self-loops.
{ // (Extra braces to hide mms.)
for (MergeMemStream mms(result); mms.next_non_empty(); ) {
Node* phi = mms.memory();
for (uint i = 1; i < req(); ++i) {
if (phi->in(i) == this) phi->set_req(i, phi);
}
}
}
// now transform the new nodes, and return the mergemem
for (MergeMemStream mms(result); mms.next_non_empty(); ) {
Node* phi = mms.memory();
mms.set_memory(phase->transform(phi));
}
if (igvn) { // Unhook.
igvn->hash_delete(hook);
for (uint i = 1; i < hook->req(); i++) {
hook->set_req(i, NULL);
}
}
// Replace self with the result.
return result;
}
}
//
// Other optimizations on the memory chain
//
const TypePtr* at = adr_type();
for( uint i=1; i<req(); ++i ) {// For all paths in
Node *ii = in(i);
Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
if (ii != new_in ) {
set_req(i, new_in);
progress = this;
}
}
}
#ifdef _LP64
// Push DecodeN/DecodeNKlass down through phi.
// The rest of phi graph will transform by split EncodeP node though phis up.
if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
bool may_push = true;
bool has_decodeN = false;
bool is_decodeN = false;
for (uint i=1; i<req(); ++i) {// For all paths in
Node *ii = in(i);
if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
// Do optimization if a non dead path exist.
if (ii->in(1)->bottom_type() != Type::TOP) {
has_decodeN = true;
is_decodeN = ii->is_DecodeN();
}
} else if (!ii->is_Phi()) {
may_push = false;
}
}
if (has_decodeN && may_push) {
PhaseIterGVN *igvn = phase->is_IterGVN();
// Make narrow type for new phi.
const Type* narrow_t;
if (is_decodeN) {
narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
} else {
narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
}
PhiNode* new_phi = new (phase->C) PhiNode(r, narrow_t);
uint orig_cnt = req();
for (uint i=1; i<req(); ++i) {// For all paths in
Node *ii = in(i);
Node* new_ii = NULL;
if (ii->is_DecodeNarrowPtr()) {
assert(ii->bottom_type() == bottom_type(), "sanity");
new_ii = ii->in(1);
} else {
assert(ii->is_Phi(), "sanity");
if (ii->as_Phi() == this) {
new_ii = new_phi;
} else {
if (is_decodeN) {
new_ii = new (phase->C) EncodePNode(ii, narrow_t);
} else {
new_ii = new (phase->C) EncodePKlassNode(ii, narrow_t);
}
igvn->register_new_node_with_optimizer(new_ii);
}
}
new_phi->set_req(i, new_ii);
}
igvn->register_new_node_with_optimizer(new_phi, this);
if (is_decodeN) {
progress = new (phase->C) DecodeNNode(new_phi, bottom_type());
} else {
progress = new (phase->C) DecodeNKlassNode(new_phi, bottom_type());
}
}
}
#endif
return progress; // Return any progress
}
//------------------------------is_tripcount-----------------------------------
bool PhiNode::is_tripcount() const {
return (in(0) != NULL && in(0)->is_CountedLoop() &&
in(0)->as_CountedLoop()->phi() == this);
}
//------------------------------out_RegMask------------------------------------
const RegMask &PhiNode::in_RegMask(uint i) const {
return i ? out_RegMask() : RegMask::Empty;
}
const RegMask &PhiNode::out_RegMask() const {
uint ideal_reg = _type->ideal_reg();
assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
if( ideal_reg == 0 ) return RegMask::Empty;
return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
}
#ifndef PRODUCT
void PhiNode::dump_spec(outputStream *st) const {
TypeNode::dump_spec(st);
if (is_tripcount()) {
st->print(" #tripcount");
}
}
#endif
//=============================================================================
const Type *GotoNode::Value( PhaseTransform *phase ) const {
// If the input is reachable, then we are executed.
// If the input is not reachable, then we are not executed.
return phase->type(in(0));
}
Node *GotoNode::Identity( PhaseTransform *phase ) {
return in(0); // Simple copy of incoming control
}
const RegMask &GotoNode::out_RegMask() const {
return RegMask::Empty;
}
//=============================================================================
const RegMask &JumpNode::out_RegMask() const {
return RegMask::Empty;
}
//=============================================================================
const RegMask &JProjNode::out_RegMask() const {
return RegMask::Empty;
}
//=============================================================================
const RegMask &CProjNode::out_RegMask() const {
return RegMask::Empty;
}
//=============================================================================
uint PCTableNode::hash() const { return Node::hash() + _size; }
uint PCTableNode::cmp( const Node &n ) const
{ return _size == ((PCTableNode&)n)._size; }
const Type *PCTableNode::bottom_type() const {
const Type** f = TypeTuple::fields(_size);
for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
return TypeTuple::make(_size, f);
}
//------------------------------Value------------------------------------------
// Compute the type of the PCTableNode. If reachable it is a tuple of
// Control, otherwise the table targets are not reachable
const Type *PCTableNode::Value( PhaseTransform *phase ) const {
if( phase->type(in(0)) == Type::CONTROL )
return bottom_type();
return Type::TOP; // All paths dead? Then so are we
}
//------------------------------Ideal------------------------------------------
// Return a node which is more "ideal" than the current node. Strip out
// control copies
Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
return remove_dead_region(phase, can_reshape) ? this : NULL;
}
//=============================================================================
uint JumpProjNode::hash() const {
return Node::hash() + _dest_bci;
}
uint JumpProjNode::cmp( const Node &n ) const {
return ProjNode::cmp(n) &&
_dest_bci == ((JumpProjNode&)n)._dest_bci;
}
#ifndef PRODUCT
void JumpProjNode::dump_spec(outputStream *st) const {
ProjNode::dump_spec(st);
st->print("@bci %d ",_dest_bci);
}
#endif
//=============================================================================
//------------------------------Value------------------------------------------
// Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
// have the default "fall_through_index" path.
const Type *CatchNode::Value( PhaseTransform *phase ) const {
// Unreachable? Then so are all paths from here.
if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
// First assume all paths are reachable
const Type** f = TypeTuple::fields(_size);
for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
// Identify cases that will always throw an exception
// () rethrow call
// () virtual or interface call with NULL receiver
// () call is a check cast with incompatible arguments
if( in(1)->is_Proj() ) {
Node *i10 = in(1)->in(0);
if( i10->is_Call() ) {
CallNode *call = i10->as_Call();
// Rethrows always throw exceptions, never return
if (call->entry_point() == OptoRuntime::rethrow_stub()) {
f[CatchProjNode::fall_through_index] = Type::TOP;
} else if( call->req() > TypeFunc::Parms ) {
const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
// Check for null receiver to virtual or interface calls
if( call->is_CallDynamicJava() &&
arg0->higher_equal(TypePtr::NULL_PTR) ) {
f[CatchProjNode::fall_through_index] = Type::TOP;
}
} // End of if not a runtime stub
} // End of if have call above me
} // End of slot 1 is not a projection
return TypeTuple::make(_size, f);
}
//=============================================================================
uint CatchProjNode::hash() const {
return Node::hash() + _handler_bci;
}
uint CatchProjNode::cmp( const Node &n ) const {
return ProjNode::cmp(n) &&
_handler_bci == ((CatchProjNode&)n)._handler_bci;
}
//------------------------------Identity---------------------------------------
// If only 1 target is possible, choose it if it is the main control
Node *CatchProjNode::Identity( PhaseTransform *phase ) {
// If my value is control and no other value is, then treat as ID
const TypeTuple *t = phase->type(in(0))->is_tuple();
if (t->field_at(_con) != Type::CONTROL) return this;
// If we remove the last CatchProj and elide the Catch/CatchProj, then we
// also remove any exception table entry. Thus we must know the call
// feeding the Catch will not really throw an exception. This is ok for
// the main fall-thru control (happens when we know a call can never throw
// an exception) or for "rethrow", because a further optimization will
// yank the rethrow (happens when we inline a function that can throw an
// exception and the caller has no handler). Not legal, e.g., for passing
// a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
// These cases MUST throw an exception via the runtime system, so the VM
// will be looking for a table entry.
Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
CallNode *call;
if (_con != TypeFunc::Control && // Bail out if not the main control.
!(proj->is_Proj() && // AND NOT a rethrow
proj->in(0)->is_Call() &&
(call = proj->in(0)->as_Call()) &&
call->entry_point() == OptoRuntime::rethrow_stub()))
return this;
// Search for any other path being control
for (uint i = 0; i < t->cnt(); i++) {
if (i != _con && t->field_at(i) == Type::CONTROL)
return this;
}
// Only my path is possible; I am identity on control to the jump
return in(0)->in(0);
}
#ifndef PRODUCT
void CatchProjNode::dump_spec(outputStream *st) const {
ProjNode::dump_spec(st);
st->print("@bci %d ",_handler_bci);
}
#endif
//=============================================================================
//------------------------------Identity---------------------------------------
// Check for CreateEx being Identity.
Node *CreateExNode::Identity( PhaseTransform *phase ) {
if( phase->type(in(1)) == Type::TOP ) return in(1);
if( phase->type(in(0)) == Type::TOP ) return in(0);
// We only come from CatchProj, unless the CatchProj goes away.
// If the CatchProj is optimized away, then we just carry the
// exception oop through.
CallNode *call = in(1)->in(0)->as_Call();
return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
? this
: call->in(TypeFunc::Parms);
}
//=============================================================================
//------------------------------Value------------------------------------------
// Check for being unreachable.
const Type *NeverBranchNode::Value( PhaseTransform *phase ) const {
if (!in(0) || in(0)->is_top()) return Type::TOP;
return bottom_type();
}
//------------------------------Ideal------------------------------------------
// Check for no longer being part of a loop
Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if (can_reshape && !in(0)->is_Loop()) {
// Dead code elimination can sometimes delete this projection so
// if it's not there, there's nothing to do.
Node* fallthru = proj_out(0);
if (fallthru != NULL) {
phase->is_IterGVN()->replace_node(fallthru, in(0));
}
return phase->C->top();
}
return NULL;
}
#ifndef PRODUCT
void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
st->print("%s", Name());
}
#endif
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