GVN.cpp File Reference (original) (raw)

Go to the source code of this file.

Classes
struct	llvm::GVNPass::Expression
struct	llvm::DenseMapInfo< GVNPass::Expression >
struct	llvm::gvn::AvailableValue
	Represents a particular available value that we know how to materialize. More...
struct	llvm::gvn::AvailableValueInBlock
	Represents an AvailableValue which can be rematerialized at the end of the associated BasicBlock. More...
class	llvm::gvn::GVNLegacyPass

Macros
#define	DEBUG_TYPE "gvn"

Enumerations
enum class	AvailabilityState : char { Unavailable = 0 , Available = 1 , SpeculativelyAvailable = 2 }

Functions
	STATISTIC (NumGVNInstr, "Number of instructions deleted")
	STATISTIC (NumGVNLoad, "Number of loads deleted")
	STATISTIC (NumGVNPRE, "Number of instructions PRE'd")
	STATISTIC (NumGVNBlocks, "Number of blocks merged")
	STATISTIC (NumGVNSimpl, "Number of instructions simplified")
	STATISTIC (NumGVNEqProp, "Number of equalities propagated")
	STATISTIC (NumPRELoad, "Number of loads PRE'd")
	STATISTIC (NumPRELoopLoad, "Number of loop loads PRE'd")
	STATISTIC (NumPRELoadMoved2CEPred, "Number of loads moved to predecessor of a critical edge in PRE")
	STATISTIC (IsValueFullyAvailableInBlockNumSpeculationsMax, "Number of blocks speculated as available in " "IsValueFullyAvailableInBlock(), max")
	STATISTIC (MaxBBSpeculationCutoffReachedTimes, "Number of times we we reached gvn-max-block-speculations cut-off " "preventing further exploration")
static bool	IsValueFullyAvailableInBlock (BasicBlock BB, DenseMap< BasicBlock , AvailabilityState > &FullyAvailableBlocks)
	Return true if we can prove that the value we're analyzing is fully available in the specified block.
static void	replaceValuesPerBlockEntry (SmallVectorImpl< AvailableValueInBlock > &ValuesPerBlock, Value OldValue, Value NewValue)
	If the specified OldValue exists in ValuesPerBlock, replace its value with NewValue.
static Value *	ConstructSSAForLoadSet (LoadInst *Load, SmallVectorImpl< AvailableValueInBlock > &ValuesPerBlock, GVNPass &GVN)
	Given a set of loads specified by ValuesPerBlock, construct SSA form, allowing us to eliminate Load.
static bool	isLifetimeStart (const Instruction *Inst)
static bool	liesBetween (const Instruction From, Instruction Between, const Instruction To, const DominatorTree DT)
	Assuming To can be reached from both From and Between, does Between lie on every path from From to To?
static const Instruction *	findMayClobberedPtrAccess (LoadInst Load, const DominatorTree DT)
static void	reportMayClobberedLoad (LoadInst Load, MemDepResult DepInfo, const DominatorTree DT, OptimizationRemarkEmitter *ORE)
	Try to locate the three instruction involved in a missed load-elimination case that is due to an intervening store.
static Value *	findDominatingValue (const MemoryLocation &Loc, Type LoadTy, Instruction From, AAResults *AA)
static void	reportLoadElim (LoadInst Load, Value AvailableValue, OptimizationRemarkEmitter *ORE)
static void	patchAndReplaceAllUsesWith (Instruction I, Value Repl)
static bool	isOnlyReachableViaThisEdge (const BasicBlockEdge &E, DominatorTree *DT)
	There is an edge from 'Src' to 'Dst'.

Variables
static cl::opt< bool >	GVNEnablePRE ("enable-pre", cl::init(true), cl::Hidden)
static cl::opt< bool >	GVNEnableLoadPRE ("enable-load-pre", cl::init(true))
static cl::opt< bool >	GVNEnableLoadInLoopPRE ("enable-load-in-loop-pre", cl::init(true))
static cl::opt< bool >	GVNEnableSplitBackedgeInLoadPRE ("enable-split-backedge-in-load-pre", cl::init(false))
static cl::opt< bool >	GVNEnableMemDep ("enable-gvn-memdep", cl::init(true))
static cl::opt< bool >	GVNEnableMemorySSA ("enable-gvn-memoryssa", cl::init(false))
static cl::opt< uint32_t >	MaxNumDeps ("gvn-max-num-deps", cl::Hidden, cl::init(100), cl::desc("Max number of dependences to attempt Load PRE (default = 100)"))
static cl::opt< uint32_t >	MaxBBSpeculations ("gvn-max-block-speculations", cl::Hidden, cl::init(600), cl::desc("Max number of blocks we're willing to speculate on (and recurse " "into) when deducing if a value is fully available or not in GVN " "(default = 600)"))
static cl::opt< uint32_t >	MaxNumVisitedInsts ("gvn-max-num-visited-insts", cl::Hidden, cl::init(100), cl::desc("Max number of visited instructions when trying to find " "dominating value of select dependency (default = 100)"))
static cl::opt< uint32_t >	MaxNumInsnsPerBlock ("gvn-max-num-insns", cl::Hidden, cl::init(100), cl::desc("Max number of instructions to scan in each basic block in GVN " "(default = 100)"))

◆ DEBUG_TYPE

◆ AvailabilityState

Enumerator
Unavailable	We know the block is not fully available. This is a fixpoint.
Available	We know the block is fully available. This is a fixpoint.
SpeculativelyAvailable	We do not know whether the block is fully available or not, but we are currently speculating that it will be. If it would have turned out that the block was, in fact, not fully available, this would have been cleaned up into an Unavailable.

Definition at line 947 of file GVN.cpp.

◆ ConstructSSAForLoadSet()

Given a set of loads specified by ValuesPerBlock, construct SSA form, allowing us to eliminate Load.

This returns the value that should be used at Load's definition site.

Definition at line 1102 of file GVN.cpp.

References llvm::SSAUpdater::AddAvailableValue(), assert(), llvm::GVNPass::getDominatorTree(), llvm::SSAUpdater::GetValueInMiddleOfBlock(), llvm::SSAUpdater::HasValueForBlock(), llvm::SSAUpdater::Initialize(), llvm::DominatorTreeBase< NodeT, IsPostDom >::properlyDominates(), and llvm::SmallVectorTemplateCommon< T, typename >::size().

◆ findDominatingValue()

Definition at line 1303 of file GVN.cpp.

References llvm::dyn_cast(), llvm::BatchAAResults::getModRefInfo(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::ilist_node_with_parent< NodeTy, ParentTy, Options >::getPrevNode(), llvm::BasicBlock::getSinglePredecessor(), llvm::BasicBlock::getTerminator(), llvm::isModSet(), and MaxNumVisitedInsts.

◆ findMayClobberedPtrAccess()

◆ isLifetimeStart()

◆ isOnlyReachableViaThisEdge()

There is an edge from 'Src' to 'Dst'.

Return true if every path from the entry block to 'Dst' passes via this edge. In particular 'Dst' must not be reachable via another edge from 'Src'.

Definition at line 2421 of file GVN.cpp.

References assert(), and E().

◆ IsValueFullyAvailableInBlock()

Return true if we can prove that the value we're analyzing is fully available in the specified block.

As we go, keep track of which blocks we know are fully alive in FullyAvailableBlocks. This map is actually a tri-state map with the following values: 0) we know the block is not fully available. 1) we know the block is fully available. 2) we do not know whether the block is fully available or not, but we are currently speculating that it will be.

Definition at line 967 of file GVN.cpp.

References llvm::SmallVectorImpl< T >::append(), assert(), Available, llvm::SmallVectorImpl< T >::clear(), llvm::SmallVectorImpl< T >::emplace_back(), llvm::SmallPtrSetImplBase::empty(), llvm::SmallVectorTemplateCommon< T, typename >::empty(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::end(), llvm::SmallPtrSetImpl< PtrType >::erase(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::find(), llvm::SmallPtrSetImpl< PtrType >::insert(), IV, MaxBBSpeculations, llvm::SmallVectorImpl< T >::pop_back_val(), llvm::pred_begin(), llvm::pred_empty(), llvm::pred_end(), SpeculativelyAvailable, llvm::succ_begin(), llvm::succ_end(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::try_emplace(), and Unavailable.

◆ liesBetween()

◆ patchAndReplaceAllUsesWith()

◆ replaceValuesPerBlockEntry()

If the specified OldValue exists in ValuesPerBlock, replace its value with NewValue.

Definition at line 1083 of file GVN.cpp.

◆ reportLoadElim()

◆ reportMayClobberedLoad()

◆ STATISTIC() [1/11]

STATISTIC	(	IsValueFullyAvailableInBlockNumSpeculationsMax	,
"Number of blocks speculated as available in " "	IsValueFullyAvailableInBlock(),
max"	)

◆ STATISTIC() [2/11]

STATISTIC	(	MaxBBSpeculationCutoffReachedTimes	,
"Number of times we we reached gvn-max-block-speculations cut-off " "preventing further exploration"	)

◆ STATISTIC() [3/11]

STATISTIC	(	NumGVNBlocks	,
"Number of blocks merged"	)

◆ STATISTIC() [4/11]

STATISTIC	(	NumGVNEqProp	,
"Number of equalities propagated"	)

◆ STATISTIC() [5/11]

STATISTIC	(	NumGVNInstr	,
"Number of instructions deleted"	)

◆ STATISTIC() [6/11]

STATISTIC	(	NumGVNLoad	,
"Number of loads deleted"	)

◆ STATISTIC() [7/11]

◆ STATISTIC() [8/11]

STATISTIC	(	NumGVNSimpl	,
"Number of instructions simplified"	)

◆ STATISTIC() [9/11]

STATISTIC	(	NumPRELoad	,
"Number of loads PRE'd"	)

◆ STATISTIC() [10/11]

STATISTIC	(	NumPRELoadMoved2CEPred	,
"Number of loads moved to predecessor of a critical edge in PRE"	)

◆ STATISTIC() [11/11]

STATISTIC	(	NumPRELoopLoad	,
"Number of loop loads PRE'd"	)

◆ GVNEnableLoadInLoopPRE

cl::opt< bool > GVNEnableLoadInLoopPRE("enable-load-in-loop-pre", cl::init(true)) ( "enable-load-in-loop-pre" , cl::init(true) )	static

◆ GVNEnableLoadPRE

cl::opt< bool > GVNEnableLoadPRE("enable-load-pre", cl::init(true)) ( "enable-load-pre" , cl::init(true) )	static

◆ GVNEnableMemDep

cl::opt< bool > GVNEnableMemDep("enable-gvn-memdep", cl::init(true)) ( "enable-gvn-memdep" , cl::init(true) )	static

◆ GVNEnableMemorySSA

cl::opt< bool > GVNEnableMemorySSA("enable-gvn-memoryssa", cl::init(false)) ( "enable-gvn-memoryssa" , cl::init(false) )	static

◆ GVNEnablePRE

cl::opt< bool > GVNEnablePRE("enable-pre", cl::init(true), cl::Hidden) ( "enable-pre" , cl::init(true) , cl::Hidden )	static

◆ GVNEnableSplitBackedgeInLoadPRE

cl::opt< bool > GVNEnableSplitBackedgeInLoadPRE("enable-split-backedge-in-load-pre", cl::init(false)) ( "enable-split-backedge-in-load-pre" , cl::init(false) )	static

◆ MaxBBSpeculations

cl::opt< uint32_t > MaxBBSpeculations("gvn-max-block-speculations", cl::Hidden, cl::init(600), cl::desc("Max number of blocks we're willing to speculate on (and recurse " "into) when deducing if a value is fully available or not in GVN " "(default = 600)")) ( "gvn-max-block-speculations" , cl::Hidden , cl::init(600) , cl::desc("Max number of blocks we're willing to speculate on (and recurse " "into) when deducing if a value is fully available or not in GVN " "(default = 600)") )

static

◆ MaxNumDeps

cl::opt< uint32_t > MaxNumDeps("gvn-max-num-deps", cl::Hidden, cl::init(100), cl::desc("Max number of dependences to attempt Load PRE (default = 100)")) ( "gvn-max-num-deps" , cl::Hidden , cl::init(100) , cl::desc("Max number of dependences to attempt Load PRE (default = 100)") )	static

◆ MaxNumInsnsPerBlock

◆ MaxNumVisitedInsts

cl::opt< uint32_t > MaxNumVisitedInsts("gvn-max-num-visited-insts", cl::Hidden, cl::init(100), cl::desc("Max number of visited instructions when trying to find " "dominating value of select dependency (default = 100)")) ( "gvn-max-num-visited-insts" , cl::Hidden , cl::init(100) , cl::desc("Max number of visited instructions when trying to find " "dominating value of select dependency (default = 100)") )

static