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android / platform / libcore / e76de189561 / . / src / hotspot / share / opto / loopnode.hpp
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/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
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#ifndef SHARE_OPTO_LOOPNODE_HPP
#define SHARE_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 OuterStripMinedLoopEndNode;
class PathFrequency;
class PhaseIdealLoop;
class CountedLoopReserveKit;
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:
uint _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,
HasReductions=128,
WasSlpAnalyzed=256,
PassedSlpAnalysis=512,
DoUnrollOnly=1024,
VectorizedLoop=2048,
HasAtomicPostLoop=4096,
HasRangeChecks=8192,
IsMultiversioned=16384,
StripMined=32768,
SubwordLoop=65536,
ProfileTripFailed=131072,
TransformedLongLoop=262144};
char _unswitch_count;
enum { _unswitch_max=3 };
char _postloop_flags;
enum { LoopNotRCEChecked = 0, LoopRCEChecked = 1, RCEPostLoop = 2 };
// Expected trip count from profile data
float _profile_trip_cnt;
public:
// Names for edge indices
enum { Self=0, EntryControl, LoopBackControl };
bool is_inner_loop() const { return _loop_flags & InnerLoop; }
void set_inner_loop() { _loop_flags |= InnerLoop; }
bool range_checks_present() const { return _loop_flags & HasRangeChecks; }
bool is_multiversioned() const { return _loop_flags & IsMultiversioned; }
bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
bool is_strip_mined() const { return _loop_flags & StripMined; }
bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
bool is_transformed_long_loop() const { return _loop_flags & TransformedLongLoop; }
void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
void mark_has_reductions() { _loop_flags |= HasReductions; }
void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
void mark_has_range_checks() { _loop_flags |= HasRangeChecks; }
void mark_is_multiversioned() { _loop_flags |= IsMultiversioned; }
void mark_strip_mined() { _loop_flags |= StripMined; }
void clear_strip_mined() { _loop_flags &= ~StripMined; }
void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
void mark_subword_loop() { _loop_flags |= SubwordLoop; }
void mark_transformed_long_loop() { _loop_flags |= TransformedLongLoop; }
int unswitch_max() { return _unswitch_max; }
int unswitch_count() { return _unswitch_count; }
int has_been_range_checked() const { return _postloop_flags & LoopRCEChecked; }
void set_has_been_range_checked() { _postloop_flags |= LoopRCEChecked; }
int is_rce_post_loop() const { return _postloop_flags & RCEPostLoop; }
void set_is_rce_post_loop() { _postloop_flags |= RCEPostLoop; }
void set_unswitch_count(int val) {
assert (val <= unswitch_max(), "too many unswitches");
_unswitch_count = val;
}
void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
float profile_trip_cnt() { return _profile_trip_cnt; }
LoopNode(Node *entry, Node *backedge)
: RegionNode(3), _loop_flags(0), _unswitch_count(0),
_postloop_flags(0), _profile_trip_cnt(COUNT_UNKNOWN) {
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
void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return NULL; }
virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return NULL; }
virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return NULL; }
virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return NULL; }
};
//------------------------------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;
// 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;
// If slp analysis is performed we record the maximum
// vector mapped unroll factor here
int _slp_maximum_unroll_factor;
public:
CountedLoopNode( Node *entry, Node *backedge )
: LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
_unrolled_count_log2(0), _node_count_before_unroll(0),
_slp_maximum_unroll_factor(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_or_null() const;
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.
bool is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
bool is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
bool is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
bool is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
bool is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; }
bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
bool has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
bool is_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
bool has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
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_notpassed_slp() {
_loop_flags &= ~PassedSlpAnalysis;
}
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; }
void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
OuterStripMinedLoopNode* outer_loop() const;
virtual IfTrueNode* outer_loop_tail() const;
virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
virtual IfFalseNode* outer_loop_exit() const;
virtual SafePointNode* outer_safepoint() const;
// If this is a main loop in a pre/main/post loop nest, walk over
// the predicates that were inserted by
// duplicate_predicates()/add_range_check_predicate()
static Node* skip_predicates_from_entry(Node* ctrl);
Node* skip_predicates();
#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 *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; }
PhiNode *phi() const {
Node *tmp = incr();
if (tmp && tmp->req() == 3) {
Node* phi = tmp->in(1);
if (phi->is_Phi()) {
return phi->as_Phi();
}
}
return NULL;
}
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
PhiNode* iv_phi = phi();
if (iv_phi == NULL) {
return NULL;
}
Node *ln = iv_phi->in(0);
if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit_or_null() == this) {
return (CountedLoopNode*)ln;
}
return NULL;
}
#ifndef PRODUCT
virtual void dump_spec(outputStream *st) const;
#endif
};
inline CountedLoopEndNode* CountedLoopNode::loopexit_or_null() const {
Node* bctrl = back_control();
if (bctrl == NULL) return NULL;
Node* lexit = bctrl->in(0);
return (CountedLoopEndNode*)
(lexit->Opcode() == Op_CountedLoopEnd ? lexit : NULL);
}
inline CountedLoopEndNode* CountedLoopNode::loopexit() const {
CountedLoopEndNode* cle = loopexit_or_null();
assert(cle != NULL, "loopexit is NULL");
return cle;
}
inline Node* CountedLoopNode::init_trip() const {
CountedLoopEndNode* cle = loopexit_or_null();
return cle != NULL ? cle->init_trip() : NULL;
}
inline Node* CountedLoopNode::stride() const {
CountedLoopEndNode* cle = loopexit_or_null();
return cle != NULL ? cle->stride() : NULL;
}
inline int CountedLoopNode::stride_con() const {
CountedLoopEndNode* cle = loopexit_or_null();
return cle != NULL ? cle->stride_con() : 0;
}
inline bool CountedLoopNode::stride_is_con() const {
CountedLoopEndNode* cle = loopexit_or_null();
return cle != NULL && cle->stride_is_con();
}
inline Node* CountedLoopNode::limit() const {
CountedLoopEndNode* cle = loopexit_or_null();
return cle != NULL ? cle->limit() : NULL;
}
inline Node* CountedLoopNode::incr() const {
CountedLoopEndNode* cle = loopexit_or_null();
return cle != NULL ? cle->incr() : NULL;
}
inline Node* CountedLoopNode::phi() const {
CountedLoopEndNode* cle = loopexit_or_null();
return cle != NULL ? cle->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(PhaseGVN* phase) const;
virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
virtual Node* Identity(PhaseGVN* phase);
};
// Support for strip mining
class OuterStripMinedLoopNode : public LoopNode {
private:
CountedLoopNode* inner_loop() const;
public:
OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
: LoopNode(entry, backedge) {
init_class_id(Class_OuterStripMinedLoop);
init_flags(Flag_is_macro);
C->add_macro_node(this);
}
virtual int Opcode() const;
virtual IfTrueNode* outer_loop_tail() const;
virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
virtual IfFalseNode* outer_loop_exit() const;
virtual SafePointNode* outer_safepoint() const;
void adjust_strip_mined_loop(PhaseIterGVN* igvn);
};
class OuterStripMinedLoopEndNode : public IfNode {
public:
OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
: IfNode(control, test, prob, cnt) {
init_class_id(Class_OuterStripMinedLoopEnd);
}
virtual int Opcode() const;
virtual const Type* Value(PhaseGVN* phase) const;
virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
bool is_expanded(PhaseGVN *phase) const;
};
// -----------------------------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 a loop has multiple backedges, this is addressed during cleanup where
// we peel off the multiple backedges, merging all edges at the bottom and
// ensuring that one proper backedge flow into the loop.
Node *_head; // Head of loop
Node *_tail; // Tail of loop
inline Node *tail(); // Handle lazy update of _tail field
inline Node *head(); // Handle lazy update of _head field
PhaseIdealLoop* _phase;
int _local_loop_unroll_limit;
int _local_loop_unroll_factor;
Node_List _body; // Loop body for inner loops
uint8_t _nest; // Nesting depth
uint8_t _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),
_local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
_nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
_safepts(NULL),
_required_safept(NULL),
_allow_optimizations(true)
{
precond(_head != NULL);
precond(_tail != NULL);
}
// Is 'l' a member of 'this'?
bool 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);
// Remove safepoints from loop. Optionally keeping one.
void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
// 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;
// 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 do_remove_empty_loop( PhaseIdealLoop *phase );
// Convert one iteration loop into normal code.
bool do_one_iteration_loop( PhaseIdealLoop *phase );
// Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
// move some loop-invariant test (usually a null-check) before the loop.
bool policy_peeling(PhaseIdealLoop *phase);
uint estimate_peeling(PhaseIdealLoop *phase);
// 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. Apply unroll
// if the loop is a counted loop and the loop body is small enough.
bool policy_unroll(PhaseIdealLoop *phase);
// Loop analyses to map to a maximal superword unrolling for vectorization.
void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
// 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;
// Estimate the number of nodes required when cloning a loop (body).
uint est_loop_clone_sz(uint factor) const;
// Estimate the number of nodes required when unrolling a loop (body).
uint est_loop_unroll_sz(uint factor) const;
// Compute loop trip count if possible
void compute_trip_count(PhaseIdealLoop* phase);
// Compute loop trip count from profile data
float compute_profile_trip_cnt_helper(Node* n);
void compute_profile_trip_cnt( PhaseIdealLoop *phase );
// Reassociate invariant expressions.
void reassociate_invariants(PhaseIdealLoop *phase);
// Reassociate invariant binary expressions.
Node* reassociate(Node* n1, PhaseIdealLoop *phase);
// Reassociate invariant add and subtract expressions.
Node* reassociate_add_sub(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop *phase);
// Return nonzero index of invariant operand if invariant and variant
// are combined with an associative binary. Helper for reassociate_invariants.
int find_invariant(Node* n, PhaseIdealLoop *phase);
// Return TRUE if "n" is associative.
bool is_associative(Node* n, Node* base=NULL);
// 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_root() { return _parent == NULL; }
// A proper/reducible loop w/o any (occasional) dead back-edge.
bool is_loop() { return !_irreducible && !tail()->is_top(); }
bool is_counted() { return is_loop() && _head->is_CountedLoop(); }
bool is_innermost() { return is_loop() && _child == NULL; }
void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
#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
private:
enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
// Estimate the number of nodes resulting from control and data flow merge.
uint est_loop_flow_merge_sz() const;
};
// -----------------------------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;
friend class CountedLoopReserveKit;
friend class ShenandoahBarrierC2Support;
friend class AutoNodeBudget;
// 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; }
public:
// 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; }
private:
// 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;
}
Node* cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
#ifdef ASSERT
void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
#endif
void copy_skeleton_predicates_to_main_loop_helper(Node* predicate, Node* init, Node* stride, IdealLoopTree* outer_loop, LoopNode* outer_main_head,
uint dd_main_head, const uint idx_before_pre_post, const uint idx_after_post_before_pre,
Node* zero_trip_guard_proj_main, Node* zero_trip_guard_proj_post, const Node_List &old_new);
void copy_skeleton_predicates_to_main_loop(CountedLoopNode* pre_head, Node* init, Node* stride, IdealLoopTree* outer_loop, LoopNode* outer_main_head,
uint dd_main_head, const uint idx_before_pre_post, const uint idx_after_post_before_pre,
Node* zero_trip_guard_proj_main, Node* zero_trip_guard_proj_post, const Node_List &old_new);
Node* clone_skeleton_predicate(Node* iff, Node* new_init, Node* new_stride, Node* predicate, Node* uncommon_proj,
Node* current_proj, IdealLoopTree* outer_loop, Node* prev_proj);
bool skeleton_predicate_has_opaque(IfNode* iff);
void update_main_loop_skeleton_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con);
void insert_loop_limit_check(ProjNode* limit_check_proj, Node* cmp_limit, Node* bol);
#ifdef ASSERT
bool only_has_infinite_loops();
#endif
public:
PhaseIterGVN &igvn() const { return _igvn; }
static bool is_canonical_loop_entry(CountedLoopNode* cl);
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;
}
}
Node *get_ctrl_no_update_helper(Node *i) const {
assert(has_ctrl(i), "should be control, not loop");
return (Node*)(((intptr_t)_nodes[i->_idx]) & ~1);
}
Node *get_ctrl_no_update(Node *i) const {
assert( has_ctrl(i), "" );
Node *n = get_ctrl_no_update_helper(i);
if (!n->in(0)) {
// Skip dead CFG nodes
do {
n = get_ctrl_no_update_helper(n);
} 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.
void lazy_update(Node *old_node, Node *new_node) {
assert(old_node != new_node, "no cycles please");
// 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);
}
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_work(Node* n, bool pinned);
void build_loop_late_post(Node* n);
void verify_strip_mined_scheduling(Node *n, Node* least);
// 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
// Perform verification that the graph is valid.
PhaseIdealLoop( PhaseIterGVN &igvn) :
PhaseTransform(Ideal_Loop),
_igvn(igvn),
_verify_me(NULL),
_verify_only(true),
_dom_lca_tags(arena()), // Thread::resource_area
_nodes_required(UINT_MAX) {
build_and_optimize(LoopOptsVerify);
}
// build the loop tree and perform any requested optimizations
void build_and_optimize(LoopOptsMode mode);
// Dominators for the sea of nodes
void Dominators();
// Compute the Ideal Node to Loop mapping
PhaseIdealLoop(PhaseIterGVN &igvn, LoopOptsMode mode) :
PhaseTransform(Ideal_Loop),
_igvn(igvn),
_verify_me(NULL),
_verify_only(false),
_dom_lca_tags(arena()), // Thread::resource_area
_nodes_required(UINT_MAX) {
build_and_optimize(mode);
}
// Verify that verify_me made the same decisions as a fresh run.
PhaseIdealLoop(PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) :
PhaseTransform(Ideal_Loop),
_igvn(igvn),
_verify_me(verify_me),
_verify_only(false),
_dom_lca_tags(arena()), // Thread::resource_area
_nodes_required(UINT_MAX) {
build_and_optimize(LoopOptsVerify);
}
public:
Node* idom_no_update(Node* d) const {
return idom_no_update(d->_idx);
}
Node* idom_no_update(uint didx) const {
assert(didx < _idom_size, "oob");
Node* n = _idom[didx];
assert(n != NULL,"Bad immediate dominator info.");
while (n->in(0) == NULL) { // Skip dead CFG nodes
n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);
assert(n != NULL,"Bad immediate dominator info.");
}
return n;
}
Node *idom(Node* d) const {
return idom(d->_idx);
}
Node *idom(uint didx) const {
Node *n = idom_no_update(didx);
_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);
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;
// 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
ResourceMark rm;
PhaseIdealLoop v(igvn);
#endif
}
// Recommended way to use PhaseIdealLoop.
// Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
ResourceMark rm;
PhaseIdealLoop v(igvn, mode);
}
// True if the method has at least 1 irreducible loop
bool _has_irreducible_loops;
// Per-Node transform
virtual Node* transform(Node* n) { return NULL; }
Node* loop_exit_control(Node* x, IdealLoopTree* loop);
Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
Node* loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi);
PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop);
bool is_counted_loop(Node* n, IdealLoopTree* &loop);
void long_loop_replace_long_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head);
bool is_long_counted_loop(Node* x, IdealLoopTree* loop, Node_List &old_new);
#ifdef ASSERT
bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
#endif
void add_empty_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
IdealLoopTree* loop, float cl_prob, float le_fcnt,
Node*& entry_control, Node*& iffalse);
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];
}
IdealLoopTree* ltree_root() const { return _ltree_root; }
// 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.
enum CloneLoopMode {
IgnoreStripMined = 0, // Only clone inner strip mined loop
CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
ControlAroundStripMined = 2 // Only clone inner strip mined loop,
// result control flow branches
// either to inner clone or outer
// strip mined loop.
};
void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
CloneLoopMode mode, Node* side_by_side_idom = NULL);
void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
IdealLoopTree* loop, IdealLoopTree* companion_loop,
Node_List*& split_if_set, Node_List*& split_bool_set,
Node_List*& split_cex_set, Node_List& worklist,
uint new_counter, CloneLoopMode mode);
void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
IdealLoopTree* outer_loop, int dd, Node_List &old_new,
Node_List& extra_data_nodes);
// 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 );
// Add post loop after the given loop.
Node *insert_post_loop(IdealLoopTree *loop, Node_List &old_new,
CountedLoopNode *main_head, CountedLoopEndNode *main_end,
Node *incr, Node *limit, CountedLoopNode *&post_head);
// Add an RCE'd post loop which we will multi-version adapt for run time test path usage
void insert_scalar_rced_post_loop( IdealLoopTree *loop, Node_List &old_new );
// Add a vector post loop between a vector main loop and the current post loop
void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
// 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 );
// Mark vector reduction candidates before loop unrolling
void mark_reductions( IdealLoopTree *loop );
// 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,
int opcode, bool if_cont_is_true_proj = true);
void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
static Node* skip_all_loop_predicates(Node* entry);
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, jint stride,
Node* range, bool upper, bool &overflow);
// Implementation of the loop predication to promote checks outside the loop
bool loop_predication_impl(IdealLoopTree *loop);
bool loop_predication_impl_helper(IdealLoopTree *loop, ProjNode* proj, ProjNode *predicate_proj,
CountedLoopNode *cl, ConNode* zero, Invariance& invar,
Deoptimization::DeoptReason reason);
bool loop_predication_should_follow_branches(IdealLoopTree *loop, ProjNode *predicate_proj, float& loop_trip_cnt);
void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
Node_List& if_proj_list);
ProjNode* insert_initial_skeleton_predicate(IfNode* iff, IdealLoopTree *loop,
ProjNode* proj, ProjNode *predicate_proj,
ProjNode* upper_bound_proj,
int scale, Node* offset,
Node* init, Node* limit, jint stride,
Node* rng, bool& overflow,
Deoptimization::DeoptReason reason);
Node* add_range_check_predicate(IdealLoopTree* loop, CountedLoopNode* cl,
Node* predicate_proj, int scale_con, Node* offset,
Node* limit, jint stride_con, Node* value);
// 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.
int do_range_check( IdealLoopTree *loop, Node_List &old_new );
// Check to see if do_range_check(...) cleaned the main loop of range-checks
void has_range_checks(IdealLoopTree *loop);
// Process post loops which have range checks and try to build a multi-version
// guard to safely determine if we can execute the post loop which was RCE'd.
bool multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop);
// Cause the rce'd post loop to optimized away, this happens if we cannot complete multiverioning
void poison_rce_post_loop(IdealLoopTree *rce_loop);
// 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,
int opcode,
CloneLoopMode mode);
// Clone a loop and return the clone head (clone_loop_head).
// Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse,
// This routine was created for usage in CountedLoopReserveKit.
//
// int(1) -> If -> IfTrue -> original_loop_head
// |
// V
// IfFalse -> clone_loop_head (returned by function pointer)
//
LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk);
// 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, bool round_up);
// 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.
Node *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 );
// Convert add to muladd to generate MuladdS2I under certain criteria
Node * convert_add_to_muladd(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 intrinsic 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;
Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
void try_move_store_after_loop(Node* n);
bool identical_backtoback_ifs(Node *n);
bool can_split_if(Node *n_ctrl);
// Determine if a method is too big for a/another round of split-if, based on
// a magic (approximate) ratio derived from the equally magic constant 35000,
// previously used for this purpose (but without relating to the node limit).
bool must_throttle_split_if() {
uint threshold = C->max_node_limit() * 2 / 5;
return C->live_nodes() > threshold;
}
// A simplistic node request tracking mechanism, where
// = UINT_MAX Request not valid or made final.
// < UINT_MAX Nodes currently requested (estimate).
uint _nodes_required;
enum { REQUIRE_MIN = 70 };
uint nodes_required() const { return _nodes_required; }
// Given the _currently_ available number of nodes, check whether there is
// "room" for an additional request or not, considering the already required
// number of nodes. Return TRUE if the new request is exceeding the node
// budget limit, otherwise return FALSE. Note that this interpretation will
// act pessimistic on additional requests when new nodes have already been
// generated since the 'begin'. This behaviour fits with the intention that
// node estimates/requests should be made upfront.
bool exceeding_node_budget(uint required = 0) {
assert(C->live_nodes() < C->max_node_limit(), "sanity");
uint available = C->max_node_limit() - C->live_nodes();
return available < required + _nodes_required + REQUIRE_MIN;
}
uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
precond(require > 0);
_nodes_required += MAX2(require, minreq);
return _nodes_required;
}
bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
}
uint require_nodes_begin() {
assert(_nodes_required == UINT_MAX, "Bad state (begin).");
_nodes_required = 0;
return C->live_nodes();
}
// When a node request is final, optionally check that the requested number
// of nodes was reasonably correct with respect to the number of new nodes
// introduced since the last 'begin'. Always check that we have not exceeded
// the maximum node limit.
void require_nodes_final(uint live_at_begin, bool check_estimate) {
assert(_nodes_required < UINT_MAX, "Bad state (final).");
#ifdef ASSERT
if (check_estimate) {
// Check that the node budget request was not off by too much (x2).
// Should this be the case we _surely_ need to improve the estimates
// used in our budget calculations.
if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
C->live_nodes() - live_at_begin, _nodes_required);
}
}
#endif
// Assert that we have stayed within the node budget limit.
assert(C->live_nodes() < C->max_node_limit(),
"Exceeding node budget limit: %d + %d > %d (request = %d)",
C->live_nodes() - live_at_begin, live_at_begin,
C->max_node_limit(), _nodes_required);
_nodes_required = UINT_MAX;
}
// Clone loop predicates to slow and fast loop when unswitching a loop
void clone_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new, ProjNode*& iffast, ProjNode*& ifslow);
ProjNode* clone_predicate_to_unswitched_loop(ProjNode* predicate_proj, Node* new_entry, Deoptimization::DeoptReason reason);
void clone_skeleton_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new, Deoptimization::DeoptReason reason,
ProjNode* old_predicate_proj, ProjNode* iffast, ProjNode* ifslow);
void check_created_predicate_for_unswitching(const Node* new_entry) const PRODUCT_RETURN;
bool _created_loop_node;
#ifdef ASSERT
void dump_real_LCA(Node* early, Node* wrong_lca);
bool check_idom_chains_intersection(const Node* n, uint& idom_idx_new, uint& idom_idx_other, const Node_List* nodes_seen) const;
#endif
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_idom(Node* n) const;
void dump(IdealLoopTree* loop, uint rpo_idx, 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
static volatile int _long_loop_candidates;
static volatile int _long_loop_nests;
static volatile int _long_loop_counted_loops;
#endif
void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
};
class AutoNodeBudget : public StackObj
{
public:
enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
: _phase(phase),
_check_at_final(chk == BUDGET_CHECK),
_nodes_at_begin(0)
{
precond(_phase != NULL);
_nodes_at_begin = _phase->require_nodes_begin();
}
~AutoNodeBudget() {
#ifndef PRODUCT
if (TraceLoopOpts) {
uint request = _phase->nodes_required();
uint delta = _phase->C->live_nodes() - _nodes_at_begin;
if (request < delta) {
tty->print_cr("Exceeding node budget: %d < %d", request, delta);
} else {
uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
// Identify the worst estimates as "poor" ones.
if (request > REQUIRE_MIN && delta > 0) {
if ((delta > REQUIRE_MIN && request > 3 * delta) ||
(delta <= REQUIRE_MIN && request > 10 * delta)) {
tty->print_cr("Poor node estimate: %d >> %d", request, delta);
}
}
}
}
#endif // PRODUCT
_phase->require_nodes_final(_nodes_at_begin, _check_at_final);
}
private:
PhaseIdealLoop* _phase;
bool _check_at_final;
uint _nodes_at_begin;
};
// This kit may be used for making of a reserved copy of a loop before this loop
// goes under non-reversible changes.
//
// Function create_reserve() creates a reserved copy (clone) of the loop.
// The reserved copy is created by calling
// PhaseIdealLoop::create_reserve_version_of_loop - see there how
// the original and reserved loops are connected in the outer graph.
// If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'.
//
// By default the reserved copy (clone) of the loop is created as dead code - it is
// dominated in the outer loop by this node chain:
// intcon(1)->If->IfFalse->reserved_copy.
// The original loop is dominated by the the same node chain but IfTrue projection:
// intcon(0)->If->IfTrue->original_loop.
//
// In this implementation of CountedLoopReserveKit the ctor includes create_reserve()
// and the dtor, checks _use_new value.
// If _use_new == false, it "switches" control to reserved copy of the loop
// by simple replacing of node intcon(1) with node intcon(0).
//
// Here is a proposed example of usage (see also SuperWord::output in superword.cpp).
//
// void CountedLoopReserveKit_example()
// {
// CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object
// if (DoReserveCopy && !lrk.has_reserved()) {
// return; //failed to create reserved loop copy
// }
// ...
// //something is wrong, switch to original loop
/// if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch
// ...
// //everything worked ok, return with the newly modified loop
// lrk.use_new();
// return; // ~CountedLoopReserveKit does nothing once use_new() was called
// }
//
// Keep in mind, that by default if create_reserve() is not followed by use_new()
// the dtor will "switch to the original" loop.
// NOTE. You you modify outside of the original loop this class is no help.
//
class CountedLoopReserveKit {
private:
PhaseIdealLoop* _phase;
IdealLoopTree* _lpt;
LoopNode* _lp;
IfNode* _iff;
LoopNode* _lp_reserved;
bool _has_reserved;
bool _use_new;
const bool _active; //may be set to false in ctor, then the object is dummy
public:
CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active);
~CountedLoopReserveKit();
void use_new() {_use_new = true;}
void set_iff(IfNode* x) {_iff = x;}
bool has_reserved() const { return _active && _has_reserved;}
private:
bool create_reserve();
};// class CountedLoopReserveKit
inline Node* IdealLoopTree::tail() {
// Handle lazy update of _tail field.
if (_tail->in(0) == NULL) {
_tail = _phase->get_ctrl(_tail);
}
return _tail;
}
inline Node* IdealLoopTree::head() {
// Handle lazy update of _head field.
if (_head->in(0) == NULL) {
_head = _phase->get_ctrl(_head);
}
return _head;
}
// 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_OPTO_LOOPNODE_HPP