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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef jit_ValueNumbering_h
#define jit_ValueNumbering_h
#include "jit/JitAllocPolicy.h"
#include "js/HashTable.h"
#include "js/Vector.h"
namespace js {
namespace jit {
class MDefinition;
class MBasicBlock;
class MIRGraph;
class MPhi;
class MIRGenerator;
class MResumePoint;
class ValueNumberer {
// Value numbering data.
class VisibleValues {
// Hash policy for ValueSet.
struct ValueHasher {
using Lookup = const MDefinition*;
using Key = MDefinition*;
static HashNumber hash(Lookup ins);
static bool match(Key k, Lookup l);
static void rekey(Key& k, Key newKey);
};
typedef HashSet<MDefinition*, ValueHasher, JitAllocPolicy> ValueSet;
ValueSet set_; // Set of visible values
public:
explicit VisibleValues(TempAllocator& alloc);
using Ptr = ValueSet::Ptr;
using AddPtr = ValueSet::AddPtr;
Ptr findLeader(const MDefinition* def) const;
AddPtr findLeaderForAdd(MDefinition* def);
[[nodiscard]] bool add(AddPtr p, MDefinition* def);
void overwrite(AddPtr p, MDefinition* def);
void forget(const MDefinition* def);
void clear();
#ifdef DEBUG
bool has(const MDefinition* def) const;
#endif
};
typedef Vector<MBasicBlock*, 4, JitAllocPolicy> BlockWorklist;
typedef Vector<MDefinition*, 4, JitAllocPolicy> DefWorklist;
MIRGenerator* const mir_;
MIRGraph& graph_;
VisibleValues values_; // Numbered values
DefWorklist deadDefs_; // Worklist for deleting values
BlockWorklist remainingBlocks_; // Blocks remaining with fewer preds
MDefinition* nextDef_; // The next definition; don't discard
size_t totalNumVisited_; // The number of blocks visited
bool rerun_; // Should we run another GVN iteration?
bool blocksRemoved_; // Have any blocks been removed?
bool updateAliasAnalysis_; // Do we care about AliasAnalysis?
bool dependenciesBroken_; // Have we broken AliasAnalysis?
bool hasOSRFixups_; // Have we created any OSR fixup blocks?
enum ImplicitUseOption { DontSetImplicitUse, SetImplicitUse };
enum class AllowEffectful : bool { No, Yes };
[[nodiscard]] bool handleUseReleased(MDefinition* def,
ImplicitUseOption implicitUseOption);
[[nodiscard]] bool discardDefsRecursively(
MDefinition* def, AllowEffectful allowEffectful = AllowEffectful::No);
[[nodiscard]] bool releaseResumePointOperands(MResumePoint* resume);
[[nodiscard]] bool releaseAndRemovePhiOperands(MPhi* phi);
[[nodiscard]] bool releaseOperands(MDefinition* def);
[[nodiscard]] bool discardDef(
MDefinition* def, AllowEffectful allowEffectful = AllowEffectful::No);
[[nodiscard]] bool processDeadDefs();
[[nodiscard]] bool fixupOSROnlyLoop(MBasicBlock* block);
[[nodiscard]] bool removePredecessorAndDoDCE(MBasicBlock* block,
MBasicBlock* pred,
size_t predIndex);
[[nodiscard]] bool removePredecessorAndCleanUp(MBasicBlock* block,
MBasicBlock* pred);
MDefinition* simplified(MDefinition* def) const;
MDefinition* leader(MDefinition* def);
bool hasLeader(const MPhi* phi, const MBasicBlock* phiBlock) const;
bool loopHasOptimizablePhi(MBasicBlock* header) const;
[[nodiscard]] bool visitDefinition(MDefinition* def);
[[nodiscard]] bool visitControlInstruction(MBasicBlock* block);
[[nodiscard]] bool visitUnreachableBlock(MBasicBlock* block);
[[nodiscard]] bool visitBlock(MBasicBlock* block);
[[nodiscard]] bool visitDominatorTree(MBasicBlock* root);
[[nodiscard]] bool visitGraph();
[[nodiscard]] bool insertOSRFixups();
[[nodiscard]] bool cleanupOSRFixups();
public:
ValueNumberer(MIRGenerator* mir, MIRGraph& graph);
enum UpdateAliasAnalysisFlag { DontUpdateAliasAnalysis, UpdateAliasAnalysis };
// Optimize the graph, performing expression simplification and
// canonicalization, eliminating statically fully-redundant expressions,
// deleting dead instructions, and removing unreachable blocks.
[[nodiscard]] bool run(UpdateAliasAnalysisFlag updateAliasAnalysis);
};
} // namespace jit
} // namespace js
#endif /* jit_ValueNumbering_h */
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