Java example source code file (loopnode.hpp)
The loopnode.hpp Java example source code
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#ifndef SHARE_VM_OPTO_LOOPNODE_HPP
#define SHARE_VM_OPTO_LOOPNODE_HPP
#include "opto/cfgnode.hpp"
#include "opto/multnode.hpp"
#include "opto/phaseX.hpp"
#include "opto/subnode.hpp"
#include "opto/type.hpp"
class CmpNode;
class CountedLoopEndNode;
class CountedLoopNode;
class IdealLoopTree;
class LoopNode;
class Node;
class PhaseIdealLoop;
class VectorSet;
class Invariance;
struct small_cache;
//
// I D E A L I Z E D L O O P S
//
// Idealized loops are the set of loops I perform more interesting
// transformations on, beyond simple hoisting.
//------------------------------LoopNode---------------------------------------
// Simple loop header. Fall in path on left, loop-back path on right.
class LoopNode : public RegionNode {
// Size is bigger to hold the flags. However, the flags do not change
// the semantics so it does not appear in the hash & cmp functions.
virtual uint size_of() const { return sizeof(*this); }
protected:
short _loop_flags;
// Names for flag bitfields
enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
MainHasNoPreLoop=4,
HasExactTripCount=8,
InnerLoop=16,
PartialPeelLoop=32,
PartialPeelFailed=64 };
char _unswitch_count;
enum { _unswitch_max=3 };
public:
// Names for edge indices
enum { Self=0, EntryControl, LoopBackControl };
int is_inner_loop() const { return _loop_flags & InnerLoop; }
void set_inner_loop() { _loop_flags |= InnerLoop; }
int is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
int partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
int unswitch_max() { return _unswitch_max; }
int unswitch_count() { return _unswitch_count; }
void set_unswitch_count(int val) {
assert (val <= unswitch_max(), "too many unswitches");
_unswitch_count = val;
}
LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) {
init_class_id(Class_Loop);
init_req(EntryControl, entry);
init_req(LoopBackControl, backedge);
}
virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
virtual int Opcode() const;
bool can_be_counted_loop(PhaseTransform* phase) const {
return req() == 3 && in(0) != NULL &&
in(1) != NULL && phase->type(in(1)) != Type::TOP &&
in(2) != NULL && phase->type(in(2)) != Type::TOP;
}
bool is_valid_counted_loop() const;
#ifndef PRODUCT
virtual void dump_spec(outputStream *st) const;
#endif
};
//------------------------------Counted Loops----------------------------------
// Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
// path (and maybe some other exit paths). The trip-counter exit is always
// last in the loop. The trip-counter have to stride by a constant;
// the exit value is also loop invariant.
// CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
// CountedLoopNode has the incoming loop control and the loop-back-control
// which is always the IfTrue before the matching CountedLoopEndNode. The
// CountedLoopEndNode has an incoming control (possibly not the
// CountedLoopNode if there is control flow in the loop), the post-increment
// trip-counter value, and the limit. The trip-counter value is always of
// the form (Op old-trip-counter stride). The old-trip-counter is produced
// by a Phi connected to the CountedLoopNode. The stride is constant.
// The Op is any commutable opcode, including Add, Mul, Xor. The
// CountedLoopEndNode also takes in the loop-invariant limit value.
// From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
// loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
// via the old-trip-counter from the Op node.
//------------------------------CountedLoopNode--------------------------------
// CountedLoopNodes head simple counted loops. CountedLoopNodes have as
// inputs the incoming loop-start control and the loop-back control, so they
// act like RegionNodes. They also take in the initial trip counter, the
// loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
// produce a loop-body control and the trip counter value. Since
// CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
class CountedLoopNode : public LoopNode {
// Size is bigger to hold _main_idx. However, _main_idx does not change
// the semantics so it does not appear in the hash & cmp functions.
virtual uint size_of() const { return sizeof(*this); }
// For Pre- and Post-loops during debugging ONLY, this holds the index of
// the Main CountedLoop. Used to assert that we understand the graph shape.
node_idx_t _main_idx;
// Known trip count calculated by compute_exact_trip_count()
uint _trip_count;
// Expected trip count from profile data
float _profile_trip_cnt;
// Log2 of original loop bodies in unrolled loop
int _unrolled_count_log2;
// Node count prior to last unrolling - used to decide if
// unroll,optimize,unroll,optimize,... is making progress
int _node_count_before_unroll;
public:
CountedLoopNode( Node *entry, Node *backedge )
: LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
_profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0),
_node_count_before_unroll(0) {
init_class_id(Class_CountedLoop);
// Initialize _trip_count to the largest possible value.
// Will be reset (lower) if the loop's trip count is known.
}
virtual int Opcode() const;
virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
Node *init_control() const { return in(EntryControl); }
Node *back_control() const { return in(LoopBackControl); }
CountedLoopEndNode *loopexit() const;
Node *init_trip() const;
Node *stride() const;
int stride_con() const;
bool stride_is_con() const;
Node *limit() const;
Node *incr() const;
Node *phi() const;
// Match increment with optional truncation
static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type);
// A 'main' loop has a pre-loop and a post-loop. The 'main' loop
// can run short a few iterations and may start a few iterations in.
// It will be RCE'd and unrolled and aligned.
// A following 'post' loop will run any remaining iterations. Used
// during Range Check Elimination, the 'post' loop will do any final
// iterations with full checks. Also used by Loop Unrolling, where
// the 'post' loop will do any epilog iterations needed. Basically,
// a 'post' loop can not profitably be further unrolled or RCE'd.
// A preceding 'pre' loop will run at least 1 iteration (to do peeling),
// it may do under-flow checks for RCE and may do alignment iterations
// so the following main loop 'knows' that it is striding down cache
// lines.
// A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
// Aligned, may be missing it's pre-loop.
int is_normal_loop() const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
int is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
int is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
int is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
int is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
int main_idx() const { return _main_idx; }
void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
void set_trip_count(uint tc) { _trip_count = tc; }
uint trip_count() { return _trip_count; }
bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
void set_exact_trip_count(uint tc) {
_trip_count = tc;
_loop_flags |= HasExactTripCount;
}
void set_nonexact_trip_count() {
_loop_flags &= ~HasExactTripCount;
}
void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
float profile_trip_cnt() { return _profile_trip_cnt; }
void double_unrolled_count() { _unrolled_count_log2++; }
int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
int node_count_before_unroll() { return _node_count_before_unroll; }
#ifndef PRODUCT
virtual void dump_spec(outputStream *st) const;
#endif
};
//------------------------------CountedLoopEndNode-----------------------------
// CountedLoopEndNodes end simple trip counted loops. They act much like
// IfNodes.
class CountedLoopEndNode : public IfNode {
public:
enum { TestControl, TestValue };
CountedLoopEndNode( Node *control, Node *test, float prob, float cnt )
: IfNode( control, test, prob, cnt) {
init_class_id(Class_CountedLoopEnd);
}
virtual int Opcode() const;
Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; }
Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
Node *phi() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
int stride_con() const;
bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); }
BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
CountedLoopNode *loopnode() const {
// The CountedLoopNode that goes with this CountedLoopEndNode may
// have been optimized out by the IGVN so be cautious with the
// pattern matching on the graph
if (phi() == NULL) {
return NULL;
}
Node *ln = phi()->in(0);
if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit() == this) {
return (CountedLoopNode*)ln;
}
return NULL;
}
#ifndef PRODUCT
virtual void dump_spec(outputStream *st) const;
#endif
};
inline CountedLoopEndNode *CountedLoopNode::loopexit() const {
Node *bc = back_control();
if( bc == NULL ) return NULL;
Node *le = bc->in(0);
if( le->Opcode() != Op_CountedLoopEnd )
return NULL;
return (CountedLoopEndNode*)le;
}
inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; }
inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; }
inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; }
inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); }
inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; }
inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; }
inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; }
//------------------------------LoopLimitNode-----------------------------
// Counted Loop limit node which represents exact final iterator value:
// trip_count = (limit - init_trip + stride - 1)/stride
// final_value= trip_count * stride + init_trip.
// Use HW instructions to calculate it when it can overflow in integer.
// Note, final_value should fit into integer since counted loop has
// limit check: limit <= max_int-stride.
class LoopLimitNode : public Node {
enum { Init=1, Limit=2, Stride=3 };
public:
LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
// Put it on the Macro nodes list to optimize during macro nodes expansion.
init_flags(Flag_is_macro);
C->add_macro_node(this);
}
virtual int Opcode() const;
virtual const Type *bottom_type() const { return TypeInt::INT; }
virtual uint ideal_reg() const { return Op_RegI; }
virtual const Type *Value( PhaseTransform *phase ) const;
virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
virtual Node *Identity( PhaseTransform *phase );
};
// -----------------------------IdealLoopTree----------------------------------
class IdealLoopTree : public ResourceObj {
public:
IdealLoopTree *_parent; // Parent in loop tree
IdealLoopTree *_next; // Next sibling in loop tree
IdealLoopTree *_child; // First child in loop tree
// The head-tail backedge defines the loop.
// If tail is NULL then this loop has multiple backedges as part of the
// same loop. During cleanup I'll peel off the multiple backedges; merge
// them at the loop bottom and flow 1 real backedge into the loop.
Node *_head; // Head of loop
Node *_tail; // Tail of loop
inline Node *tail(); // Handle lazy update of _tail field
PhaseIdealLoop* _phase;
Node_List _body; // Loop body for inner loops
uint8 _nest; // Nesting depth
uint8 _irreducible:1, // True if irreducible
_has_call:1, // True if has call safepoint
_has_sfpt:1, // True if has non-call safepoint
_rce_candidate:1; // True if candidate for range check elimination
Node_List* _safepts; // List of safepoints in this loop
Node_List* _required_safept; // A inner loop cannot delete these safepts;
bool _allow_optimizations; // Allow loop optimizations
IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
: _parent(0), _next(0), _child(0),
_head(head), _tail(tail),
_phase(phase),
_safepts(NULL),
_required_safept(NULL),
_allow_optimizations(true),
_nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0)
{ }
// Is 'l' a member of 'this'?
int is_member( const IdealLoopTree *l ) const; // Test for nested membership
// Set loop nesting depth. Accumulate has_call bits.
int set_nest( uint depth );
// Split out multiple fall-in edges from the loop header. Move them to a
// private RegionNode before the loop. This becomes the loop landing pad.
void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
// Split out the outermost loop from this shared header.
void split_outer_loop( PhaseIdealLoop *phase );
// Merge all the backedges from the shared header into a private Region.
// Feed that region as the one backedge to this loop.
void merge_many_backedges( PhaseIdealLoop *phase );
// Split shared headers and insert loop landing pads.
// Insert a LoopNode to replace the RegionNode.
// Returns TRUE if loop tree is structurally changed.
bool beautify_loops( PhaseIdealLoop *phase );
// Perform optimization to use the loop predicates for null checks and range checks.
// Applies to any loop level (not just the innermost one)
bool loop_predication( PhaseIdealLoop *phase);
// Perform iteration-splitting on inner loops. Split iterations to
// avoid range checks or one-shot null checks. Returns false if the
// current round of loop opts should stop.
bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
// Driver for various flavors of iteration splitting. Returns false
// if the current round of loop opts should stop.
bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
// Given dominators, try to find loops with calls that must always be
// executed (call dominates loop tail). These loops do not need non-call
// safepoints (ncsfpt).
void check_safepts(VectorSet &visited, Node_List &stack);
// Allpaths backwards scan from loop tail, terminating each path at first safepoint
// encountered.
void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
// Convert to counted loops where possible
void counted_loop( PhaseIdealLoop *phase );
// Check for Node being a loop-breaking test
Node *is_loop_exit(Node *iff) const;
// Returns true if ctrl is executed on every complete iteration
bool dominates_backedge(Node* ctrl);
// Remove simplistic dead code from loop body
void DCE_loop_body();
// Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
// Replace with a 1-in-10 exit guess.
void adjust_loop_exit_prob( PhaseIdealLoop *phase );
// Return TRUE or FALSE if the loop should never be RCE'd or aligned.
// Useful for unrolling loops with NO array accesses.
bool policy_peel_only( PhaseIdealLoop *phase ) const;
// Return TRUE or FALSE if the loop should be unswitched -- clone
// loop with an invariant test
bool policy_unswitching( PhaseIdealLoop *phase ) const;
// Micro-benchmark spamming. Remove empty loops.
bool policy_do_remove_empty_loop( PhaseIdealLoop *phase );
// Convert one iteration loop into normal code.
bool policy_do_one_iteration_loop( PhaseIdealLoop *phase );
// Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
// make some loop-invariant test (usually a null-check) happen before the
// loop.
bool policy_peeling( PhaseIdealLoop *phase ) const;
// Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
// known trip count in the counted loop node.
bool policy_maximally_unroll( PhaseIdealLoop *phase ) const;
// Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
// the loop is a CountedLoop and the body is small enough.
bool policy_unroll( PhaseIdealLoop *phase ) const;
// Return TRUE or FALSE if the loop should be range-check-eliminated.
// Gather a list of IF tests that are dominated by iteration splitting;
// also gather the end of the first split and the start of the 2nd split.
bool policy_range_check( PhaseIdealLoop *phase ) const;
// Return TRUE or FALSE if the loop should be cache-line aligned.
// Gather the expression that does the alignment. Note that only
// one array base can be aligned in a loop (unless the VM guarantees
// mutual alignment). Note that if we vectorize short memory ops
// into longer memory ops, we may want to increase alignment.
bool policy_align( PhaseIdealLoop *phase ) const;
// Return TRUE if "iff" is a range check.
bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const;
// Compute loop exact trip count if possible
void compute_exact_trip_count( PhaseIdealLoop *phase );
// Compute loop trip count from profile data
void compute_profile_trip_cnt( PhaseIdealLoop *phase );
// Reassociate invariant expressions.
void reassociate_invariants(PhaseIdealLoop *phase);
// Reassociate invariant add and subtract expressions.
Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase);
// Return nonzero index of invariant operand if invariant and variant
// are combined with an Add or Sub. Helper for reassociate_invariants.
int is_invariant_addition(Node* n, PhaseIdealLoop *phase);
// Return true if n is invariant
bool is_invariant(Node* n) const;
// Put loop body on igvn work list
void record_for_igvn();
bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); }
bool is_inner() { return is_loop() && _child == NULL; }
bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); }
#ifndef PRODUCT
void dump_head( ) const; // Dump loop head only
void dump() const; // Dump this loop recursively
void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const;
#endif
};
// -----------------------------PhaseIdealLoop---------------------------------
// Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a
// loop tree. Drives the loop-based transformations on the ideal graph.
class PhaseIdealLoop : public PhaseTransform {
friend class IdealLoopTree;
friend class SuperWord;
// Pre-computed def-use info
PhaseIterGVN &_igvn;
// Head of loop tree
IdealLoopTree *_ltree_root;
// Array of pre-order numbers, plus post-visited bit.
// ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
// ODD for post-visited. Other bits are the pre-order number.
uint *_preorders;
uint _max_preorder;
const PhaseIdealLoop* _verify_me;
bool _verify_only;
// Allocate _preorders[] array
void allocate_preorders() {
_max_preorder = C->unique()+8;
_preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
memset(_preorders, 0, sizeof(uint) * _max_preorder);
}
// Allocate _preorders[] array
void reallocate_preorders() {
if ( _max_preorder < C->unique() ) {
_preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
_max_preorder = C->unique();
}
memset(_preorders, 0, sizeof(uint) * _max_preorder);
}
// Check to grow _preorders[] array for the case when build_loop_tree_impl()
// adds new nodes.
void check_grow_preorders( ) {
if ( _max_preorder < C->unique() ) {
uint newsize = _max_preorder<<1; // double size of array
_preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
_max_preorder = newsize;
}
}
// Check for pre-visited. Zero for NOT visited; non-zero for visited.
int is_visited( Node *n ) const { return _preorders[n->_idx]; }
// Pre-order numbers are written to the Nodes array as low-bit-set values.
void set_preorder_visited( Node *n, int pre_order ) {
assert( !is_visited( n ), "already set" );
_preorders[n->_idx] = (pre_order<<1);
};
// Return pre-order number.
int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
// Check for being post-visited.
// Should be previsited already (checked with assert(is_visited(n))).
int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
// Mark as post visited
void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
// Set/get control node out. Set lower bit to distinguish from IdealLoopTree
// Returns true if "n" is a data node, false if it's a control node.
bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; }
// clear out dead code after build_loop_late
Node_List _deadlist;
// Support for faster execution of get_late_ctrl()/dom_lca()
// when a node has many uses and dominator depth is deep.
Node_Array _dom_lca_tags;
void init_dom_lca_tags();
void clear_dom_lca_tags();
// Helper for debugging bad dominance relationships
bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
// Inline wrapper for frequent cases:
// 1) only one use
// 2) a use is the same as the current LCA passed as 'n1'
Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
assert( n->is_CFG(), "" );
// Fast-path NULL lca
if( lca != NULL && lca != n ) {
assert( lca->is_CFG(), "" );
// find LCA of all uses
n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
}
return find_non_split_ctrl(n);
}
Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
// Helper function for directing control inputs away from CFG split
// points.
Node *find_non_split_ctrl( Node *ctrl ) const {
if (ctrl != NULL) {
if (ctrl->is_MultiBranch()) {
ctrl = ctrl->in(0);
}
assert(ctrl->is_CFG(), "CFG");
}
return ctrl;
}
public:
bool has_node( Node* n ) const {
guarantee(n != NULL, "No Node.");
return _nodes[n->_idx] != NULL;
}
// check if transform created new nodes that need _ctrl recorded
Node *get_late_ctrl( Node *n, Node *early );
Node *get_early_ctrl( Node *n );
Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
void set_early_ctrl( Node *n );
void set_subtree_ctrl( Node *root );
void set_ctrl( Node *n, Node *ctrl ) {
assert( !has_node(n) || has_ctrl(n), "" );
assert( ctrl->in(0), "cannot set dead control node" );
assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
_nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) );
}
// Set control and update loop membership
void set_ctrl_and_loop(Node* n, Node* ctrl) {
IdealLoopTree* old_loop = get_loop(get_ctrl(n));
IdealLoopTree* new_loop = get_loop(ctrl);
if (old_loop != new_loop) {
if (old_loop->_child == NULL) old_loop->_body.yank(n);
if (new_loop->_child == NULL) new_loop->_body.push(n);
}
set_ctrl(n, ctrl);
}
// Control nodes can be replaced or subsumed. During this pass they
// get their replacement Node in slot 1. Instead of updating the block
// location of all Nodes in the subsumed block, we lazily do it. As we
// pull such a subsumed block out of the array, we write back the final
// correct block.
Node *get_ctrl( Node *i ) {
assert(has_node(i), "");
Node *n = get_ctrl_no_update(i);
_nodes.map( i->_idx, (Node*)((intptr_t)n + 1) );
assert(has_node(i) && has_ctrl(i), "");
assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
return n;
}
// true if CFG node d dominates CFG node n
bool is_dominator(Node *d, Node *n);
// return get_ctrl for a data node and self(n) for a CFG node
Node* ctrl_or_self(Node* n) {
if (has_ctrl(n))
return get_ctrl(n);
else {
assert (n->is_CFG(), "must be a CFG node");
return n;
}
}
private:
Node *get_ctrl_no_update( Node *i ) const {
assert( has_ctrl(i), "" );
Node *n = (Node*)(((intptr_t)_nodes[i->_idx]) & ~1);
if (!n->in(0)) {
// Skip dead CFG nodes
do {
n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);
} while (!n->in(0));
n = find_non_split_ctrl(n);
}
return n;
}
// Check for loop being set
// "n" must be a control node. Returns true if "n" is known to be in a loop.
bool has_loop( Node *n ) const {
assert(!has_node(n) || !has_ctrl(n), "");
return has_node(n);
}
// Set loop
void set_loop( Node *n, IdealLoopTree *loop ) {
_nodes.map(n->_idx, (Node*)loop);
}
// Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
// the 'old_node' with 'new_node'. Kill old-node. Add a reference
// from old_node to new_node to support the lazy update. Reference
// replaces loop reference, since that is not needed for dead node.
public:
void lazy_update( Node *old_node, Node *new_node ) {
assert( old_node != new_node, "no cycles please" );
//old_node->set_req( 1, new_node /*NO DU INFO*/ );
// Nodes always have DU info now, so re-use the side array slot
// for this node to provide the forwarding pointer.
_nodes.map( old_node->_idx, (Node*)((intptr_t)new_node + 1) );
}
void lazy_replace( Node *old_node, Node *new_node ) {
_igvn.replace_node( old_node, new_node );
lazy_update( old_node, new_node );
}
void lazy_replace_proj( Node *old_node, Node *new_node ) {
assert( old_node->req() == 1, "use this for Projs" );
_igvn.hash_delete(old_node); // Must hash-delete before hacking edges
old_node->add_req( NULL );
lazy_replace( old_node, new_node );
}
private:
// Place 'n' in some loop nest, where 'n' is a CFG node
void build_loop_tree();
int build_loop_tree_impl( Node *n, int pre_order );
// Insert loop into the existing loop tree. 'innermost' is a leaf of the
// loop tree, not the root.
IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
// Place Data nodes in some loop nest
void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
void build_loop_late_post ( Node* n );
// Array of immediate dominance info for each CFG node indexed by node idx
private:
uint _idom_size;
Node **_idom; // Array of immediate dominators
uint *_dom_depth; // Used for fast LCA test
GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
Node* idom_no_update(Node* d) const {
assert(d->_idx < _idom_size, "oob");
Node* n = _idom[d->_idx];
assert(n != NULL,"Bad immediate dominator info.");
while (n->in(0) == NULL) { // Skip dead CFG nodes
//n = n->in(1);
n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);
assert(n != NULL,"Bad immediate dominator info.");
}
return n;
}
Node *idom(Node* d) const {
uint didx = d->_idx;
Node *n = idom_no_update(d);
_idom[didx] = n; // Lazily remove dead CFG nodes from table.
return n;
}
uint dom_depth(Node* d) const {
guarantee(d != NULL, "Null dominator info.");
guarantee(d->_idx < _idom_size, "");
return _dom_depth[d->_idx];
}
void set_idom(Node* d, Node* n, uint dom_depth);
// Locally compute IDOM using dom_lca call
Node *compute_idom( Node *region ) const;
// Recompute dom_depth
void recompute_dom_depth();
// Is safept not required by an outer loop?
bool is_deleteable_safept(Node* sfpt);
// Replace parallel induction variable (parallel to trip counter)
void replace_parallel_iv(IdealLoopTree *loop);
// Perform verification that the graph is valid.
PhaseIdealLoop( PhaseIterGVN &igvn) :
PhaseTransform(Ideal_Loop),
_igvn(igvn),
_dom_lca_tags(arena()), // Thread::resource_area
_verify_me(NULL),
_verify_only(true) {
build_and_optimize(false, false);
}
// build the loop tree and perform any requested optimizations
void build_and_optimize(bool do_split_if, bool skip_loop_opts);
public:
// Dominators for the sea of nodes
void Dominators();
Node *dom_lca( Node *n1, Node *n2 ) const {
return find_non_split_ctrl(dom_lca_internal(n1, n2));
}
Node *dom_lca_internal( Node *n1, Node *n2 ) const;
// Compute the Ideal Node to Loop mapping
PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false) :
PhaseTransform(Ideal_Loop),
_igvn(igvn),
_dom_lca_tags(arena()), // Thread::resource_area
_verify_me(NULL),
_verify_only(false) {
build_and_optimize(do_split_ifs, skip_loop_opts);
}
// Verify that verify_me made the same decisions as a fresh run.
PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) :
PhaseTransform(Ideal_Loop),
_igvn(igvn),
_dom_lca_tags(arena()), // Thread::resource_area
_verify_me(verify_me),
_verify_only(false) {
build_and_optimize(false, false);
}
// Build and verify the loop tree without modifying the graph. This
// is useful to verify that all inputs properly dominate their uses.
static void verify(PhaseIterGVN& igvn) {
#ifdef ASSERT
PhaseIdealLoop v(igvn);
#endif
}
// True if the method has at least 1 irreducible loop
bool _has_irreducible_loops;
// Per-Node transform
virtual Node *transform( Node *a_node ) { return 0; }
bool is_counted_loop( Node *x, IdealLoopTree *loop );
Node* exact_limit( IdealLoopTree *loop );
// Return a post-walked LoopNode
IdealLoopTree *get_loop( Node *n ) const {
// Dead nodes have no loop, so return the top level loop instead
if (!has_node(n)) return _ltree_root;
assert(!has_ctrl(n), "");
return (IdealLoopTree*)_nodes[n->_idx];
}
// Is 'n' a (nested) member of 'loop'?
int is_member( const IdealLoopTree *loop, Node *n ) const {
return loop->is_member(get_loop(n)); }
// This is the basic building block of the loop optimizations. It clones an
// entire loop body. It makes an old_new loop body mapping; with this
// mapping you can find the new-loop equivalent to an old-loop node. All
// new-loop nodes are exactly equal to their old-loop counterparts, all
// edges are the same. All exits from the old-loop now have a RegionNode
// that merges the equivalent new-loop path. This is true even for the
// normal "loop-exit" condition. All uses of loop-invariant old-loop values
// now come from (one or more) Phis that merge their new-loop equivalents.
// Parameter side_by_side_idom:
// When side_by_size_idom is NULL, the dominator tree is constructed for
// the clone loop to dominate the original. Used in construction of
// pre-main-post loop sequence.
// When nonnull, the clone and original are side-by-side, both are
// dominated by the passed in side_by_side_idom node. Used in
// construction of unswitched loops.
void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
Node* side_by_side_idom = NULL);
// If we got the effect of peeling, either by actually peeling or by
// making a pre-loop which must execute at least once, we can remove
// all loop-invariant dominated tests in the main body.
void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
// Generate code to do a loop peel for the given loop (and body).
// old_new is a temp array.
void do_peeling( IdealLoopTree *loop, Node_List &old_new );
// Add pre and post loops around the given loop. These loops are used
// during RCE, unrolling and aligning loops.
void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
// If Node n lives in the back_ctrl block, we clone a private version of n
// in preheader_ctrl block and return that, otherwise return n.
Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
// Take steps to maximally unroll the loop. Peel any odd iterations, then
// unroll to do double iterations. The next round of major loop transforms
// will repeat till the doubled loop body does all remaining iterations in 1
// pass.
void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
// Unroll the loop body one step - make each trip do 2 iterations.
void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
// Return true if exp is a constant times an induction var
bool is_scaled_iv(Node* exp, Node* iv, int* p_scale);
// Return true if exp is a scaled induction var plus (or minus) constant
bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0);
// Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
Deoptimization::DeoptReason reason);
void register_control(Node* n, IdealLoopTree *loop, Node* pred);
// Clone loop predicates to cloned loops (peeled, unswitched)
static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry,
Deoptimization::DeoptReason reason,
PhaseIdealLoop* loop_phase,
PhaseIterGVN* igvn);
static Node* clone_loop_predicates(Node* old_entry, Node* new_entry,
bool clone_limit_check,
PhaseIdealLoop* loop_phase,
PhaseIterGVN* igvn);
Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
static Node* skip_loop_predicates(Node* entry);
// Find a good location to insert a predicate
static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason);
// Find a predicate
static Node* find_predicate(Node* entry);
// Construct a range check for a predicate if
BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl,
int scale, Node* offset,
Node* init, Node* limit, Node* stride,
Node* range, bool upper);
// Implementation of the loop predication to promote checks outside the loop
bool loop_predication_impl(IdealLoopTree *loop);
// Helper function to collect predicate for eliminating the useless ones
void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1);
void eliminate_useless_predicates();
// Change the control input of expensive nodes to allow commoning by
// IGVN when it is guaranteed to not result in a more frequent
// execution of the expensive node. Return true if progress.
bool process_expensive_nodes();
// Check whether node has become unreachable
bool is_node_unreachable(Node *n) const {
return !has_node(n) || n->is_unreachable(_igvn);
}
// Eliminate range-checks and other trip-counter vs loop-invariant tests.
void do_range_check( IdealLoopTree *loop, Node_List &old_new );
// Create a slow version of the loop by cloning the loop
// and inserting an if to select fast-slow versions.
ProjNode* create_slow_version_of_loop(IdealLoopTree *loop,
Node_List &old_new);
// Clone loop with an invariant test (that does not exit) and
// insert a clone of the test that selects which version to
// execute.
void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
// Find candidate "if" for unswitching
IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const;
// Range Check Elimination uses this function!
// Constrain the main loop iterations so the affine function:
// low_limit <= scale_con * I + offset < upper_limit
// always holds true. That is, either increase the number of iterations in
// the pre-loop or the post-loop until the condition holds true in the main
// loop. Scale_con, offset and limit are all loop invariant.
void add_constraint( int stride_con, int scale_con, Node *offset, Node *low_limit, Node *upper_limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit );
// Helper function for add_constraint().
Node* adjust_limit( int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl );
// Partially peel loop up through last_peel node.
bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
// Create a scheduled list of nodes control dependent on ctrl set.
void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
// Has a use in the vector set
bool has_use_in_set( Node* n, VectorSet& vset );
// Has use internal to the vector set (ie. not in a phi at the loop head)
bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
// clone "n" for uses that are outside of loop
int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
// clone "n" for special uses that are in the not_peeled region
void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
// Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
#ifdef ASSERT
// Validate the loop partition sets: peel and not_peel
bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
// Ensure that uses outside of loop are of the right form
bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
uint orig_exit_idx, uint clone_exit_idx);
bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
#endif
// Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
int stride_of_possible_iv( Node* iff );
bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
// Return the (unique) control output node that's in the loop (if it exists.)
Node* stay_in_loop( Node* n, IdealLoopTree *loop);
// Insert a signed compare loop exit cloned from an unsigned compare.
IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
// Utility to register node "n" with PhaseIdealLoop
void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth);
// Utility to create an if-projection
ProjNode* proj_clone(ProjNode* p, IfNode* iff);
// Force the iff control output to be the live_proj
Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
// Insert a region before an if projection
RegionNode* insert_region_before_proj(ProjNode* proj);
// Insert a new if before an if projection
ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
// Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
// "Nearly" because all Nodes have been cloned from the original in the loop,
// but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
// through the Phi recursively, and return a Bool.
BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop );
CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop );
// Rework addressing expressions to get the most loop-invariant stuff
// moved out. We'd like to do all associative operators, but it's especially
// important (common) to do address expressions.
Node *remix_address_expressions( Node *n );
// Attempt to use a conditional move instead of a phi/branch
Node *conditional_move( Node *n );
// Reorganize offset computations to lower register pressure.
// Mostly prevent loop-fallout uses of the pre-incremented trip counter
// (which are then alive with the post-incremented trip counter
// forcing an extra register move)
void reorg_offsets( IdealLoopTree *loop );
// Check for aggressive application of 'split-if' optimization,
// using basic block level info.
void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack );
Node *split_if_with_blocks_pre ( Node *n );
void split_if_with_blocks_post( Node *n );
Node *has_local_phi_input( Node *n );
// Mark an IfNode as being dominated by a prior test,
// without actually altering the CFG (and hence IDOM info).
void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false );
// Split Node 'n' through merge point
Node *split_thru_region( Node *n, Node *region );
// Split Node 'n' through merge point if there is enough win.
Node *split_thru_phi( Node *n, Node *region, int policy );
// Found an If getting its condition-code input from a Phi in the
// same block. Split thru the Region.
void do_split_if( Node *iff );
// Conversion of fill/copy patterns into intrisic versions
bool do_intrinsify_fill();
bool intrinsify_fill(IdealLoopTree* lpt);
bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
Node*& shift, Node*& offset);
private:
// Return a type based on condition control flow
const TypeInt* filtered_type( Node *n, Node* n_ctrl);
const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); }
// Helpers for filtered type
const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
// Helper functions
Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
void handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true );
bool split_up( Node *n, Node *blk1, Node *blk2 );
void sink_use( Node *use, Node *post_loop );
Node *place_near_use( Node *useblock ) const;
bool _created_loop_node;
public:
void set_created_loop_node() { _created_loop_node = true; }
bool created_loop_node() { return _created_loop_node; }
void register_new_node( Node *n, Node *blk );
#ifdef ASSERT
void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
#endif
#ifndef PRODUCT
void dump( ) const;
void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const;
void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const;
void verify() const; // Major slow :-)
void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const;
IdealLoopTree *get_loop_idx(Node* n) const {
// Dead nodes have no loop, so return the top level loop instead
return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root;
}
// Print some stats
static void print_statistics();
static int _loop_invokes; // Count of PhaseIdealLoop invokes
static int _loop_work; // Sum of PhaseIdealLoop x _unique
#endif
};
inline Node* IdealLoopTree::tail() {
// Handle lazy update of _tail field
Node *n = _tail;
//while( !n->in(0) ) // Skip dead CFG nodes
//n = n->in(1);
if (n->in(0) == NULL)
n = _phase->get_ctrl(n);
_tail = n;
return n;
}
// Iterate over the loop tree using a preorder, left-to-right traversal.
//
// Example that visits all counted loops from within PhaseIdealLoop
//
// for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
// IdealLoopTree* lpt = iter.current();
// if (!lpt->is_counted()) continue;
// ...
class LoopTreeIterator : public StackObj {
private:
IdealLoopTree* _root;
IdealLoopTree* _curnt;
public:
LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
bool done() { return _curnt == NULL; } // Finished iterating?
void next(); // Advance to next loop tree
IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
};
#endif // SHARE_VM_OPTO_LOOPNODE_HPP
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