#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Sequence.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/GuardUtils.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/MemorySSA.h"
#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/MemoryModelRelaxationAnnotations.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/NoFolder.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Use.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/BranchProbability.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <algorithm>
#include <cassert>
#include <climits>
#include <cstddef>
#include <cstdint>
#include <iterator>
#include <map>
#include <optional>
#include <set>
#include <tuple>
#include <utility>
#include <vector>

Macros
#define	DEBUG_TYPE "simplifycfg"

Enumerations
enum	SkipFlags { SkipReadMem = 1 , SkipSideEffect = 2 , SkipImplicitControlFlow = 4 }

Functions
	STATISTIC (NumBitMaps, "Number of switch instructions turned into bitmaps")

	STATISTIC (NumLinearMaps, "Number of switch instructions turned into linear mapping")

	STATISTIC (NumLookupTables, "Number of switch instructions turned into lookup tables")

	STATISTIC (NumLookupTablesHoles, "Number of switch instructions turned into lookup tables (holes checked)")

	STATISTIC (NumTableCmpReuses, "Number of reused switch table lookup compares")

	STATISTIC (NumFoldValueComparisonIntoPredecessors, "Number of value comparisons folded into predecessor basic blocks")

	STATISTIC (NumFoldBranchToCommonDest, "Number of branches folded into predecessor basic block")

	STATISTIC (NumHoistCommonCode, "Number of common instruction 'blocks' hoisted up to the begin block")

	STATISTIC (NumHoistCommonInstrs, "Number of common instructions hoisted up to the begin block")

	STATISTIC (NumSinkCommonCode, "Number of common instruction 'blocks' sunk down to the end block")

	STATISTIC (NumSinkCommonInstrs, "Number of common instructions sunk down to the end block")

	STATISTIC (NumSpeculations, "Number of speculative executed instructions")

	STATISTIC (NumInvokes, "Number of invokes with empty resume blocks simplified into calls")

	STATISTIC (NumInvokesMerged, "Number of invokes that were merged together")

	STATISTIC (NumInvokeSetsFormed, "Number of invoke sets that were formed")

static bool	incomingValuesAreCompatible (BasicBlock BB, ArrayRef< BasicBlock > IncomingBlocks, SmallPtrSetImpl< Value * > *EquivalenceSet=nullptr)
	Return true if all the PHI nodes in the basic block `BB` receive compatible (identical) incoming values when coming from all of the predecessor blocks that are specified in `IncomingBlocks`.

static bool	safeToMergeTerminators (Instruction SI1, Instruction SI2, SmallSetVector< BasicBlock , 4 > FailBlocks=nullptr)
	Return true if it is safe to merge these two terminator instructions together.

static void	addPredecessorToBlock (BasicBlock Succ, BasicBlock NewPred, BasicBlock ExistPred, MemorySSAUpdater MSSAU=nullptr)
	Update PHI nodes in Succ to indicate that there will now be entries in it from the 'NewPred' block.

static InstructionCost	computeSpeculationCost (const User *I, const TargetTransformInfo &TTI)
	Compute an abstract "cost" of speculating the given instruction, which is assumed to be safe to speculate.

static bool	dominatesMergePoint (Value V, BasicBlock BB, SmallPtrSetImpl< Instruction * > &AggressiveInsts, InstructionCost &Cost, InstructionCost Budget, const TargetTransformInfo &TTI, unsigned Depth=0)
	If we have a merge point of an "if condition" as accepted above, return true if the specified value dominates the block.

static ConstantInt *	getConstantInt (Value *V, const DataLayout &DL)
	Extract ConstantInt from value, looking through IntToPtr and PointerNullValue.

static void	eraseTerminatorAndDCECond (Instruction TI, MemorySSAUpdater MSSAU=nullptr)

static void	eliminateBlockCases (BasicBlock *BB, std::vector< ValueEqualityComparisonCase > &Cases)
	Given a vector of bb/value pairs, remove any entries in the list that match the specified block.

static bool	valuesOverlap (std::vector< ValueEqualityComparisonCase > &C1, std::vector< ValueEqualityComparisonCase > &C2)
	Return true if there are any keys in C1 that exist in C2 as well.

static void	setBranchWeights (SwitchInst *SI, ArrayRef< uint32_t > Weights, bool IsExpected)

static void	setBranchWeights (Instruction *I, uint32_t TrueWeight, uint32_t FalseWeight, bool IsExpected)

static int	constantIntSortPredicate (ConstantInt const P1, ConstantInt const P2)

static void	getBranchWeights (Instruction *TI, SmallVectorImpl< uint64_t > &Weights)
	Get Weights of a given terminator, the default weight is at the front of the vector.

static void	fitWeights (MutableArrayRef< uint64_t > Weights)
	Keep halving the weights until all can fit in uint32_t.

static void	cloneInstructionsIntoPredecessorBlockAndUpdateSSAUses (BasicBlock BB, BasicBlock PredBlock, ValueToValueMapTy &VMap)

static bool	isSafeToHoistInvoke (BasicBlock BB1, BasicBlock BB2, Instruction I1, Instruction I2)

static unsigned	skippedInstrFlags (Instruction *I)

static bool	isSafeToHoistInstr (Instruction *I, unsigned Flags)

static bool	passingValueIsAlwaysUndefined (Value V, Instruction I, bool PtrValueMayBeModified)
	Check if passing a value to an instruction will cause undefined behavior.

static bool	shouldHoistCommonInstructions (Instruction I1, Instruction I2, const TargetTransformInfo &TTI)
	Helper function for hoistCommonCodeFromSuccessors.

static void	hoistLockstepIdenticalDbgVariableRecords (Instruction TI, Instruction I1, SmallVectorImpl< Instruction * > &OtherInsts)
	Hoists DbgVariableRecords from `I1` and `OtherInstrs` that are identical in lock-step to `TI`.

static bool	areIdenticalUpToCommutativity (const Instruction I1, const Instruction I2)

static bool	isLifeTimeMarker (const Instruction *I)

static bool	replacingOperandWithVariableIsCheap (const Instruction *I, int OpIdx)

static bool	canSinkInstructions (ArrayRef< Instruction * > Insts, DenseMap< const Use , SmallVector< Value , 4 > > &PHIOperands)

static void	sinkLastInstruction (ArrayRef< BasicBlock * > Blocks)

static bool	sinkCommonCodeFromPredecessors (BasicBlock BB, DomTreeUpdater DTU)
	Check whether BB's predecessors end with unconditional branches.

static void	mergeCompatibleInvokesImpl (ArrayRef< InvokeInst * > Invokes, DomTreeUpdater *DTU)

static bool	mergeCompatibleInvokes (BasicBlock BB, DomTreeUpdater DTU)
	If this block is a `landingpad` exception handling block, categorize all the predecessor `invoke`s into sets, with all `invoke`s in each set being "mergeable" together, and then merge invokes in each set together.

static Value *	isSafeToSpeculateStore (Instruction I, BasicBlock BrBB, BasicBlock StoreBB, BasicBlock EndBB)
	Determine if we can hoist sink a sole store instruction out of a conditional block.

static bool	validateAndCostRequiredSelects (BasicBlock BB, BasicBlock ThenBB, BasicBlock *EndBB, unsigned &SpeculatedInstructions, InstructionCost &Cost, const TargetTransformInfo &TTI)
	Estimate the cost of the insertion(s) and check that the PHI nodes can be converted to selects.

static bool	isProfitableToSpeculate (const BranchInst *BI, bool Invert, const TargetTransformInfo &TTI)

static bool	blockIsSimpleEnoughToThreadThrough (BasicBlock *BB)
	Return true if we can thread a branch across this block.

static ConstantInt *	getKnownValueOnEdge (Value V, BasicBlock From, BasicBlock *To)

static std::optional< bool >	foldCondBranchOnValueKnownInPredecessorImpl (BranchInst BI, DomTreeUpdater DTU, const DataLayout &DL, AssumptionCache *AC)
	If we have a conditional branch on something for which we know the constant value in predecessors (e.g.

static bool	foldCondBranchOnValueKnownInPredecessor (BranchInst BI, DomTreeUpdater DTU, const DataLayout &DL, AssumptionCache *AC)

static bool	foldTwoEntryPHINode (PHINode PN, const TargetTransformInfo &TTI, DomTreeUpdater DTU, const DataLayout &DL, bool SpeculateUnpredictables)
	Given a BB that starts with the specified two-entry PHI node, see if we can eliminate it.

static Value *	createLogicalOp (IRBuilderBase &Builder, Instruction::BinaryOps Opc, Value LHS, Value RHS, const Twine &Name="")

static bool	extractPredSuccWeights (BranchInst PBI, BranchInst BI, uint64_t &PredTrueWeight, uint64_t &PredFalseWeight, uint64_t &SuccTrueWeight, uint64_t &SuccFalseWeight)
	Return true if either PBI or BI has branch weight available, and store the weights in {Pred\|Succ}{True\|False}Weight.

static std::optional< std::tuple< BasicBlock *, Instruction::BinaryOps, bool > >	shouldFoldCondBranchesToCommonDestination (BranchInst BI, BranchInst PBI, const TargetTransformInfo *TTI)
	Determine if the two branches share a common destination and deduce a glue that joins the branches' conditions to arrive at the common destination if that would be profitable.

static bool	performBranchToCommonDestFolding (BranchInst BI, BranchInst PBI, DomTreeUpdater DTU, MemorySSAUpdater MSSAU, const TargetTransformInfo *TTI)

static bool	isVectorOp (Instruction &I)
	Return if an instruction's type or any of its operands' types are a vector type.

static StoreInst *	findUniqueStoreInBlocks (BasicBlock BB1, BasicBlock BB2)

static Value *	ensureValueAvailableInSuccessor (Value V, BasicBlock BB, Value *AlternativeV=nullptr)

static bool	mergeConditionalStoreToAddress (BasicBlock PTB, BasicBlock PFB, BasicBlock QTB, BasicBlock QFB, BasicBlock PostBB, Value Address, bool InvertPCond, bool InvertQCond, DomTreeUpdater *DTU, const DataLayout &DL, const TargetTransformInfo &TTI)

static bool	mergeConditionalStores (BranchInst PBI, BranchInst QBI, DomTreeUpdater *DTU, const DataLayout &DL, const TargetTransformInfo &TTI)

static bool	tryWidenCondBranchToCondBranch (BranchInst PBI, BranchInst BI, DomTreeUpdater *DTU)
	If the previous block ended with a widenable branch, determine if reusing the target block is profitable and legal.

static bool	SimplifyCondBranchToCondBranch (BranchInst PBI, BranchInst BI, DomTreeUpdater *DTU, const DataLayout &DL, const TargetTransformInfo &TTI)
	If we have a conditional branch as a predecessor of another block, this function tries to simplify it.

static bool	isCleanupBlockEmpty (iterator_range< BasicBlock::iterator > R)

static bool	removeEmptyCleanup (CleanupReturnInst RI, DomTreeUpdater DTU)

static bool	mergeCleanupPad (CleanupReturnInst *RI)

static bool	casesAreContiguous (SmallVectorImpl< ConstantInt * > &Cases)

static void	createUnreachableSwitchDefault (SwitchInst Switch, DomTreeUpdater DTU, bool RemoveOrigDefaultBlock=true)

static bool	eliminateDeadSwitchCases (SwitchInst SI, DomTreeUpdater DTU, AssumptionCache *AC, const DataLayout &DL)
	Compute masked bits for the condition of a switch and use it to remove dead cases.

static PHINode *	findPHIForConditionForwarding (ConstantInt CaseValue, BasicBlock BB, int *PhiIndex)
	If BB would be eligible for simplification by TryToSimplifyUncondBranchFromEmptyBlock (i.e.

static bool	forwardSwitchConditionToPHI (SwitchInst *SI)
	Try to forward the condition of a switch instruction to a phi node dominated by the switch, if that would mean that some of the destination blocks of the switch can be folded away.

static bool	validLookupTableConstant (Constant *C, const TargetTransformInfo &TTI)
	Return true if the backend will be able to handle initializing an array of constants like C.

static Constant *	lookupConstant (Value V, const SmallDenseMap< Value , Constant * > &ConstantPool)
	If V is a Constant, return it.

static Constant *	constantFold (Instruction I, const DataLayout &DL, const SmallDenseMap< Value , Constant * > &ConstantPool)
	Try to fold instruction I into a constant.

static bool	getCaseResults (SwitchInst SI, ConstantInt CaseVal, BasicBlock CaseDest, BasicBlock CommonDest, SmallVectorImpl< std::pair< PHINode , Constant * > > &Res, const DataLayout &DL, const TargetTransformInfo &TTI)
	Try to determine the resulting constant values in phi nodes at the common destination basic block, *CommonDest, for one of the case destionations CaseDest corresponding to value CaseVal (0 for the default case), of a switch instruction SI.

static size_t	mapCaseToResult (ConstantInt CaseVal, SwitchCaseResultVectorTy &UniqueResults, Constant Result)

static bool	initializeUniqueCases (SwitchInst SI, PHINode &PHI, BasicBlock &CommonDest, SwitchCaseResultVectorTy &UniqueResults, Constant &DefaultResult, const DataLayout &DL, const TargetTransformInfo &TTI, uintptr_t MaxUniqueResults)

static Value *	foldSwitchToSelect (const SwitchCaseResultVectorTy &ResultVector, Constant DefaultResult, Value Condition, IRBuilder<> &Builder)

static void	removeSwitchAfterSelectFold (SwitchInst SI, PHINode PHI, Value SelectValue, IRBuilder<> &Builder, DomTreeUpdater DTU)

static bool	trySwitchToSelect (SwitchInst SI, IRBuilder<> &Builder, DomTreeUpdater DTU, const DataLayout &DL, const TargetTransformInfo &TTI)
	If a switch is only used to initialize one or more phi nodes in a common successor block with only two different constant values, try to replace the switch with a select.

static bool	isTypeLegalForLookupTable (Type *Ty, const TargetTransformInfo &TTI, const DataLayout &DL)

static bool	isSwitchDense (uint64_t NumCases, uint64_t CaseRange)

static bool	isSwitchDense (ArrayRef< int64_t > Values)

static bool	shouldBuildLookupTable (SwitchInst SI, uint64_t TableSize, const TargetTransformInfo &TTI, const DataLayout &DL, const SmallDenseMap< PHINode , Type * > &ResultTypes)
	Determine whether a lookup table should be built for this switch, based on the number of cases, size of the table, and the types of the results.

static bool	shouldUseSwitchConditionAsTableIndex (ConstantInt &MinCaseVal, const ConstantInt &MaxCaseVal, bool HasDefaultResults, const SmallDenseMap< PHINode , Type > &ResultTypes, const DataLayout &DL, const TargetTransformInfo &TTI)

static void	reuseTableCompare (User PhiUser, BasicBlock PhiBlock, BranchInst RangeCheckBranch, Constant DefaultValue, const SmallVectorImpl< std::pair< ConstantInt , Constant > > &Values)
	Try to reuse the switch table index compare.

static bool	switchToLookupTable (SwitchInst SI, IRBuilder<> &Builder, DomTreeUpdater DTU, const DataLayout &DL, const TargetTransformInfo &TTI)
	If the switch is only used to initialize one or more phi nodes in a common successor block with different constant values, replace the switch with lookup tables.

static bool	reduceSwitchRange (SwitchInst *SI, IRBuilder<> &Builder, const DataLayout &DL, const TargetTransformInfo &TTI)
	Try to transform a switch that has "holes" in it to a contiguous sequence of cases.

static bool	simplifySwitchOfPowersOfTwo (SwitchInst *SI, IRBuilder<> &Builder, const DataLayout &DL, const TargetTransformInfo &TTI)
	Tries to transform switch of powers of two to reduce switch range.

static bool	simplifySwitchOfCmpIntrinsic (SwitchInst SI, IRBuilderBase &Builder, DomTreeUpdater DTU)
	Fold switch over ucmp/scmp intrinsic to br if two of the switch arms have the same destination.

static bool	tryToMergeLandingPad (LandingPadInst LPad, BranchInst BI, BasicBlock BB, DomTreeUpdater DTU)
	Given an block with only a single landing pad and a unconditional branch try to find another basic block which this one can be merged with.

static BasicBlock *	allPredecessorsComeFromSameSource (BasicBlock *BB)

static bool	mergeNestedCondBranch (BranchInst BI, DomTreeUpdater DTU)
	Fold the following pattern: bb0: br i1 cond1, label bb1, label bb2 bb1: br i1 cond2, label bb3, label bb4 bb2: br i1 cond2, label bb4, label bb3 bb3: ... bb4: ... into bb0: cond = xor i1 cond1, cond2 br i1 cond, label bb4, label bb3 bb3: ... bb4: ... NOTE: cond2 always dominates the terminator of bb0.

static bool	removeUndefIntroducingPredecessor (BasicBlock BB, DomTreeUpdater DTU, AssumptionCache *AC)
	If BB has an incoming value that will always trigger undefined behavior (eg.

Variables
static cl::opt< unsigned >	PHINodeFoldingThreshold ("phi-node-folding-threshold", cl::Hidden, cl::init(2), cl::desc("Control the amount of phi node folding to perform (default = 2)"))

static cl::opt< unsigned >	TwoEntryPHINodeFoldingThreshold ("two-entry-phi-node-folding-threshold", cl::Hidden, cl::init(4), cl::desc("Control the maximal total instruction cost that we are willing " "to speculatively execute to fold a 2-entry PHI node into a " "select (default = 4)"))

static cl::opt< bool >	HoistCommon ("simplifycfg-hoist-common", cl::Hidden, cl::init(true), cl::desc("Hoist common instructions up to the parent block"))

static cl::opt< unsigned >	HoistCommonSkipLimit ("simplifycfg-hoist-common-skip-limit", cl::Hidden, cl::init(20), cl::desc("Allow reordering across at most this many " "instructions when hoisting"))

static cl::opt< bool >	SinkCommon ("simplifycfg-sink-common", cl::Hidden, cl::init(true), cl::desc("Sink common instructions down to the end block"))

static cl::opt< bool >	HoistCondStores ("simplifycfg-hoist-cond-stores", cl::Hidden, cl::init(true), cl::desc("Hoist conditional stores if an unconditional store precedes"))

static cl::opt< bool >	MergeCondStores ("simplifycfg-merge-cond-stores", cl::Hidden, cl::init(true), cl::desc("Hoist conditional stores even if an unconditional store does not " "precede - hoist multiple conditional stores into a single " "predicated store"))

static cl::opt< bool >	MergeCondStoresAggressively ("simplifycfg-merge-cond-stores-aggressively", cl::Hidden, cl::init(false), cl::desc("When merging conditional stores, do so even if the resultant " "basic blocks are unlikely to be if-converted as a result"))

static cl::opt< bool >	SpeculateOneExpensiveInst ("speculate-one-expensive-inst", cl::Hidden, cl::init(true), cl::desc("Allow exactly one expensive instruction to be speculatively " "executed"))

static cl::opt< unsigned >	MaxSpeculationDepth ("max-speculation-depth", cl::Hidden, cl::init(10), cl::desc("Limit maximum recursion depth when calculating costs of " "speculatively executed instructions"))

static cl::opt< int >	MaxSmallBlockSize ("simplifycfg-max-small-block-size", cl::Hidden, cl::init(10), cl::desc("Max size of a block which is still considered " "small enough to thread through"))

static cl::opt< unsigned >	BranchFoldThreshold ("simplifycfg-branch-fold-threshold", cl::Hidden, cl::init(2), cl::desc("Maximum cost of combining conditions when " "folding branches"))

static cl::opt< unsigned >	BranchFoldToCommonDestVectorMultiplier ("simplifycfg-branch-fold-common-dest-vector-multiplier", cl::Hidden, cl::init(2), cl::desc("Multiplier to apply to threshold when determining whether or not " "to fold branch to common destination when vector operations are " "present"))

static cl::opt< bool >	EnableMergeCompatibleInvokes ("simplifycfg-merge-compatible-invokes", cl::Hidden, cl::init(true), cl::desc("Allow SimplifyCFG to merge invokes together when appropriate"))

static cl::opt< unsigned >	MaxSwitchCasesPerResult ("max-switch-cases-per-result", cl::Hidden, cl::init(16), cl::desc("Limit cases to analyze when converting a switch to select"))

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE "simplifycfg"

Definition at line 93 of file SimplifyCFG.cpp.

Enumeration Type Documentation

◆ SkipFlags

enum SkipFlags

Enumerator
SkipReadMem
SkipSideEffect
SkipImplicitControlFlow

Definition at line 1441 of file SimplifyCFG.cpp.

Function Documentation

◆ addPredecessorToBlock()

static void addPredecessorToBlock	(	BasicBlock *	Succ,
		BasicBlock *	NewPred,
		BasicBlock *	ExistPred,
		MemorySSAUpdater *	MSSAU = `nullptr`
	)

static

Update PHI nodes in Succ to indicate that there will now be entries in it from the 'NewPred' block.

The values that will be flowing into the PHI nodes will be the same as those coming in from ExistPred, an existing predecessor of Succ.

Definition at line 373 of file SimplifyCFG.cpp.

References llvm::BasicBlock::phis().

Referenced by foldCondBranchOnValueKnownInPredecessorImpl(), performBranchToCommonDestFolding(), SimplifyCondBranchToCondBranch(), and switchToLookupTable().

◆ allPredecessorsComeFromSameSource()

static BasicBlock * allPredecessorsComeFromSameSource ( BasicBlock * BB )

static

Definition at line 7498 of file SimplifyCFG.cpp.

References P, and llvm::predecessors().

◆ areIdenticalUpToCommutativity()

static bool areIdenticalUpToCommutativity	(	const Instruction *	I1,
		const Instruction *	I2
	)

static

Definition at line 1586 of file SimplifyCFG.cpp.

References llvm::drop_begin(), llvm::equal(), llvm::User::getOperand(), and llvm::User::operands().

◆ blockIsSimpleEnoughToThreadThrough()

static bool blockIsSimpleEnoughToThreadThrough ( BasicBlock * BB )

static

Return true if we can thread a branch across this block.

Definition at line 3274 of file SimplifyCFG.cpp.

References llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), I, llvm::BasicBlock::instructionsWithoutDebug(), MaxSmallBlockSize, llvm::reverse(), and Size.

Referenced by foldCondBranchOnValueKnownInPredecessorImpl().

◆ canSinkInstructions()

static bool canSinkInstructions	(	ArrayRef< Instruction * >	Insts,
		DenseMap< const Use , SmallVector< Value , 4 > > &	PHIOperands
	)

static

Definition at line 1953 of file SimplifyCFG.cpp.

References llvm::all_of(), llvm::any_of(), assert(), llvm::CallingConv::C, llvm::canReplaceOperandWithVariable(), llvm::equal(), llvm::ArrayRef< T >::front(), llvm::User::getNumOperands(), llvm::User::getOperand(), llvm::User::getOperandUse(), I, isLifeTimeMarker(), replacingOperandWithVariableIsCheap(), and llvm::Value::uses().

Referenced by sinkCommonCodeFromPredecessors().

◆ casesAreContiguous()

static bool casesAreContiguous ( SmallVectorImpl< ConstantInt * > & Cases )

static

Definition at line 5507 of file SimplifyCFG.cpp.

References llvm::array_pod_sort(), assert(), llvm::SmallVectorTemplateCommon< T, typename >::begin(), constantIntSortPredicate(), llvm::SmallVectorTemplateCommon< T, typename >::end(), I, and llvm::SmallVectorBase< Size_T >::size().

◆ cloneInstructionsIntoPredecessorBlockAndUpdateSSAUses()

static void cloneInstructionsIntoPredecessorBlockAndUpdateSSAUses	(	BasicBlock *	BB,
		BasicBlock *	PredBlock,
		ValueToValueMapTy &	VMap
	)

static

◆ computeSpeculationCost()

static InstructionCost computeSpeculationCost	(	const User *	I,
		const TargetTransformInfo &	TTI
	)

static

Compute an abstract "cost" of speculating the given instruction, which is assumed to be safe to speculate.

TCC_Free means cheap, TCC_Basic means less cheap, and TCC_Expensive means prohibitively expensive.

Definition at line 387 of file SimplifyCFG.cpp.

References assert(), llvm::TargetTransformInfo::getInstructionCost(), I, llvm::isSafeToSpeculativelyExecute(), and llvm::TargetTransformInfo::TCK_SizeAndLatency.

Referenced by dominatesMergePoint(), and validateAndCostRequiredSelects().

◆ constantFold()

static Constant * constantFold	(	Instruction *	I,
		const DataLayout &	DL,
		const SmallDenseMap< Value , Constant > &	ConstantPool
	)

static

Try to fold instruction I into a constant.

This works for simple instructions such as binary operations where both operands are constant or can be replaced by constants from the ConstantPool. Returns the resulting constant on success, 0 otherwise.

Definition at line 5904 of file SimplifyCFG.cpp.

References A, llvm::ConstantFoldInstOperands(), DL, I, lookupConstant(), N, llvm::SmallVectorTemplateBase< T, bool >::push_back(), and Select.

Referenced by getCaseResults().

◆ constantIntSortPredicate()

static int constantIntSortPredicate	(	ConstantInt const	P1,
		ConstantInt const	P2
	)

static

Definition at line 1056 of file SimplifyCFG.cpp.

References LHS, and RHS.

Referenced by casesAreContiguous().

◆ createLogicalOp()

static Value * createLogicalOp	(	IRBuilderBase &	Builder,
		Instruction::BinaryOps	Opc,
		Value *	LHS,
		Value *	RHS,
		const Twine &	Name = `""`
	)

static

Definition at line 3701 of file SimplifyCFG.cpp.

References llvm::IRBuilderBase::CreateBinOp(), llvm::IRBuilderBase::CreateLogicalAnd(), llvm::IRBuilderBase::CreateLogicalOr(), llvm::impliesPoison(), LHS, llvm_unreachable, Name, and RHS.

Referenced by performBranchToCommonDestFolding(), and SimplifyCondBranchToCondBranch().

◆ createUnreachableSwitchDefault()

static void createUnreachableSwitchDefault	(	SwitchInst *	Switch,
		DomTreeUpdater *	DTU,
		bool	RemoveOrigDefaultBlock = `true`
	)

static

Definition at line 5518 of file SimplifyCFG.cpp.

References llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), llvm::BasicBlock::Create(), llvm::dbgs(), llvm::BasicBlock::getContext(), llvm::Value::getName(), llvm::BasicBlock::getParent(), llvm::is_contained(), LLVM_DEBUG, llvm::SmallVectorTemplateBase< T, bool >::push_back(), and llvm::successors().

Referenced by eliminateDeadSwitchCases().

◆ dominatesMergePoint()

static bool dominatesMergePoint	(	Value *	V,
		BasicBlock *	BB,
		SmallPtrSetImpl< Instruction * > &	AggressiveInsts,
		InstructionCost &	Cost,
		InstructionCost	Budget,
		const TargetTransformInfo &	TTI,
		unsigned	Depth = `0`
	)

static

If we have a merge point of an "if condition" as accepted above, return true if the specified value dominates the block.

We don't handle the true generality of domination here, just a special case which works well enough for us.

If AggressiveInsts is non-null, and if V does not dominate BB, we check to see if V (which must be an instruction) and its recursive operands that do not dominate BB have a combined cost lower than Budget and are non-trapping. If both are true, the instruction is inserted into the set and true is returned.

The cost for most non-trapping instructions is defined as 1 except for Select whose cost is 2.

After this function returns, Cost is increased by the cost of V plus its non-dominating operands. If that cost is greater than Budget, false is returned and Cost is undefined.

Definition at line 412 of file SimplifyCFG.cpp.

References computeSpeculationCost(), llvm::SmallPtrSetImpl< PtrType >::count(), llvm::Depth, dominatesMergePoint(), llvm::SmallPtrSetImplBase::empty(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), I, llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::BranchInst::isConditional(), llvm::isSafeToSpeculativelyExecute(), llvm::InstructionCost::isValid(), MaxSpeculationDepth, and SpeculateOneExpensiveInst.

Referenced by dominatesMergePoint(), and foldTwoEntryPHINode().

◆ eliminateBlockCases()

static void eliminateBlockCases	(	BasicBlock *	BB,
		std::vector< ValueEqualityComparisonCase > &	Cases
	)

static

Given a vector of bb/value pairs, remove any entries in the list that match the specified block.

Definition at line 823 of file SimplifyCFG.cpp.

References llvm::erase().

◆ eliminateDeadSwitchCases()

static bool eliminateDeadSwitchCases	(	SwitchInst *	SI,
		DomTreeUpdater *	DTU,
		AssumptionCache *	AC,
		const DataLayout &	DL
	)

static

Compute masked bits for the condition of a switch and use it to remove dead cases.

Definition at line 5673 of file SimplifyCFG.cpp.

References llvm::SwitchInstProfUpdateWrapper::addCase(), llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), assert(), llvm::computeKnownBits(), llvm::ComputeMaxSignificantBits(), Cond, llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::count(), createUnreachableSwitchDefault(), llvm::dbgs(), DL, llvm::SmallVectorBase< Size_T >::empty(), llvm::KnownBits::getBitWidth(), llvm::Type::getIntegerBitWidth(), llvm::APInt::getSignificantBits(), llvm::SwitchInstProfUpdateWrapper::getSuccessorWeight(), llvm::APInt::intersects(), llvm::APInt::isSubsetOf(), LLVM_DEBUG, llvm::KnownBits::One, llvm::popcount(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::SwitchInstProfUpdateWrapper::removeCase(), llvm::SwitchInstProfUpdateWrapper::setSuccessorWeight(), llvm::Successor, and llvm::KnownBits::Zero.

◆ ensureValueAvailableInSuccessor()

static Value * ensureValueAvailableInSuccessor	(	Value *	V,
		BasicBlock *	BB,
		Value *	AlternativeV = `nullptr`
	)

static

Definition at line 4047 of file SimplifyCFG.cpp.

References assert(), llvm::BasicBlock::begin(), llvm::PHINode::Create(), llvm::PoisonValue::get(), getParent(), llvm::BasicBlock::getSingleSuccessor(), llvm::BasicBlock::hasNPredecessors(), I, PHI, llvm::pred_begin(), and llvm::predecessors().

Referenced by mergeConditionalStoreToAddress().

◆ eraseTerminatorAndDCECond()

static void eraseTerminatorAndDCECond	(	Instruction *	TI,
		MemorySSAUpdater *	MSSAU = `nullptr`
	)

static

Definition at line 756 of file SimplifyCFG.cpp.

References Cond, llvm::Instruction::eraseFromParent(), and llvm::RecursivelyDeleteTriviallyDeadInstructions().

◆ extractPredSuccWeights()

static bool extractPredSuccWeights	(	BranchInst *	PBI,
		BranchInst *	BI,
		uint64_t &	PredTrueWeight,
		uint64_t &	PredFalseWeight,
		uint64_t &	SuccTrueWeight,
		uint64_t &	SuccFalseWeight
	)

static

Return true if either PBI or BI has branch weight available, and store the weights in {Pred|Succ}{True|False}Weight.

If one of PBI and BI does not have branch weight, use 1:1 as its weight.

Definition at line 3717 of file SimplifyCFG.cpp.

References llvm::extractBranchWeights().

Referenced by performBranchToCommonDestFolding(), and SimplifyCondBranchToCondBranch().

◆ findPHIForConditionForwarding()

static PHINode * findPHIForConditionForwarding	(	ConstantInt *	CaseValue,
		BasicBlock *	BB,
		int *	PhiIndex
	)

static

If BB would be eligible for simplification by TryToSimplifyUncondBranchFromEmptyBlock (i.e.

it is empty and terminated by an unconditional branch), look at the phi node for BB in the successor block and see if the incoming value is equal to CaseValue. If so, return the phi node, and set PhiIndex to BB's index in the phi node.

Definition at line 5775 of file SimplifyCFG.cpp.

References assert(), llvm::BasicBlock::getFirstNonPHIOrDbg(), llvm::BasicBlock::getSinglePredecessor(), llvm::BasicBlock::getTerminator(), Idx, PHI, and llvm::BasicBlock::phis().

Referenced by forwardSwitchConditionToPHI().

◆ findUniqueStoreInBlocks()

static StoreInst * findUniqueStoreInBlocks	(	BasicBlock *	BB1,
		BasicBlock *	BB2
	)

static

Definition at line 4030 of file SimplifyCFG.cpp.

References I.

Referenced by mergeConditionalStoreToAddress().

◆ fitWeights()

static void fitWeights ( MutableArrayRef< uint64_t > Weights )

static

Keep halving the weights until all can fit in uint32_t.

Definition at line 1086 of file SimplifyCFG.cpp.

References llvm::countl_zero(), I, llvm::max_element(), and llvm::Offset.

Referenced by mergeNestedCondBranch(), performBranchToCommonDestFolding(), and SimplifyCondBranchToCondBranch().

◆ foldCondBranchOnValueKnownInPredecessor()

static bool foldCondBranchOnValueKnownInPredecessor	(	BranchInst *	BI,
		DomTreeUpdater *	DTU,
		const DataLayout &	DL,
		AssumptionCache *	AC
	)

static

Definition at line 3487 of file SimplifyCFG.cpp.

References DL, and foldCondBranchOnValueKnownInPredecessorImpl().

◆ foldCondBranchOnValueKnownInPredecessorImpl()

static std::optional< bool > foldCondBranchOnValueKnownInPredecessorImpl	(	BranchInst *	BI,
		DomTreeUpdater *	DTU,
		const DataLayout &	DL,
		AssumptionCache *	AC
	)

static

If we have a conditional branch on something for which we know the constant value in predecessors (e.g.

a phi node in the current block), thread edges from the predecessor to their ultimate destination.

Definition at line 3330 of file SimplifyCFG.cpp.

References addPredecessorToBlock(), llvm::any_of(), llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), llvm::BasicBlock::begin(), blockIsSimpleEnoughToThreadThrough(), Cond, llvm::dbgs(), DL, llvm::MapVector< KeyT, ValueT, MapType, VectorType >::empty(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::end(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::find(), llvm::FoldSingleEntryPHINodes(), llvm::BranchInst::getCondition(), llvm::Instruction::getDebugLoc(), llvm::PHINode::getIncomingBlock(), llvm::PHINode::getIncomingValueForBlock(), getKnownValueOnEdge(), llvm::Value::getName(), llvm::PHINode::getNumIncomingValues(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::ConstantInt::getZExtValue(), llvm::PHINode::incoming_values(), llvm::MapVector< KeyT, ValueT, MapType, VectorType >::insert(), LLVM_DEBUG, llvm::MergeBlockIntoPredecessor(), N, llvm::predecessors(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::AssumptionCache::registerAssumption(), llvm::BasicBlock::removePredecessor(), llvm::Instruction::setDebugLoc(), llvm::BranchInst::setSuccessor(), llvm::simplifyInstruction(), and llvm::SplitBlockPredecessors().

Referenced by foldCondBranchOnValueKnownInPredecessor().

◆ foldSwitchToSelect()

static Value * foldSwitchToSelect	(	const SwitchCaseResultVectorTy &	ResultVector,
		Constant *	DefaultResult,
		Value *	Condition,
		IRBuilder<> &	Builder
	)

static

Definition at line 6079 of file SimplifyCFG.cpp.

References llvm::And, llvm::IRBuilderBase::CreateAnd(), llvm::IRBuilderBase::CreateICmpEQ(), llvm::IRBuilderBase::CreateOr(), llvm::IRBuilderBase::CreateSelect(), llvm::IRBuilderBase::CreateSub(), llvm::ConstantInt::getBitWidth(), llvm::Constant::getNullValue(), llvm::ConstantInt::getValue(), llvm::APInt::getZero(), llvm::Constant::isNullValue(), llvm::isPowerOf2_32(), llvm::Log2_32(), llvm::APInt::popcount(), and llvm::ArrayRef< T >::size().

Referenced by trySwitchToSelect().

◆ foldTwoEntryPHINode()

static bool foldTwoEntryPHINode	(	PHINode *	PN,
		const TargetTransformInfo &	TTI,
		DomTreeUpdater *	DTU,
		const DataLayout &	DL,
		bool	SpeculateUnpredictables
	)

static

Given a BB that starts with the specified two-entry PHI node, see if we can eliminate it.

Definition at line 3503 of file SimplifyCFG.cpp.

References llvm::any_of(), llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), assert(), llvm::BasicBlock::begin(), llvm::PHINode::blocks(), llvm::copy_if(), llvm::SmallPtrSetImpl< PtrType >::count(), llvm::IRBuilderBase::CreateBr(), llvm::IRBuilderBase::CreateSelect(), llvm::dbgs(), DL, dominatesMergePoint(), llvm::Instruction::eraseFromParent(), llvm::extractBranchWeights(), llvm::TargetTransformInfo::getBranchMispredictPenalty(), llvm::BranchProbability::getBranchProbability(), llvm::BranchProbability::getCompl(), llvm::BranchInst::getCondition(), llvm::Instruction::getFastMathFlags(), llvm::GetIfCondition(), llvm::PHINode::getIncomingValue(), llvm::PHINode::getIncomingValueForBlock(), llvm::Instruction::getMetadata(), llvm::Value::getName(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::TargetTransformInfo::getPredictableBranchThreshold(), llvm::BranchInst::getSuccessor(), llvm::Value::getType(), llvm::BasicBlock::hasAddressTaken(), llvm::hoistAllInstructionsInto(), I, II, llvm::Type::isIntegerTy(), LLVM_DEBUG, llvm::PatternMatch::m_AnyIntegralConstant(), llvm::PatternMatch::m_BinOp(), llvm::PatternMatch::m_CombineOr(), llvm::PatternMatch::m_ImmConstant(), llvm::PatternMatch::m_Not(), llvm::PatternMatch::m_Select(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::Value::replaceAllUsesWith(), llvm::IRBuilderBase::setFastMathFlags(), llvm::simplifyInstruction(), llvm::SmallVectorBase< Size_T >::size(), llvm::Successor, llvm::successors(), std::swap(), llvm::Value::takeName(), llvm::TargetTransformInfo::TCC_Basic, and TwoEntryPHINodeFoldingThreshold.

◆ forwardSwitchConditionToPHI()

static bool forwardSwitchConditionToPHI ( SwitchInst * SI )

static

Try to forward the condition of a switch instruction to a phi node dominated by the switch, if that would mean that some of the destination blocks of the switch can be folded away.

Return true if a change is made.

Definition at line 5806 of file SimplifyCFG.cpp.

References llvm::count(), findPHIForConditionForwarding(), llvm::is_contained(), llvm::BasicBlock::phis(), and llvm::SmallVectorBase< Size_T >::size().

◆ getBranchWeights()

static void getBranchWeights	(	Instruction *	TI,
		SmallVectorImpl< uint64_t > &	Weights
	)

static

Get Weights of a given terminator, the default weight is at the front of the vector.

If TI is a conditional eq, we need to swap the branch-weight metadata.

Definition at line 1068 of file SimplifyCFG.cpp.

References assert(), llvm::SmallVectorTemplateCommon< T, typename >::back(), llvm::extractFromBranchWeightMD64(), llvm::SmallVectorTemplateCommon< T, typename >::front(), llvm::BranchInst::getCondition(), llvm::Instruction::getMetadata(), llvm::CmpInst::getPredicate(), llvm::SmallVectorBase< Size_T >::size(), and std::swap().

◆ getCaseResults()

static bool getCaseResults	(	SwitchInst *	SI,
		ConstantInt *	CaseVal,
		BasicBlock *	CaseDest,
		BasicBlock **	CommonDest,
		SmallVectorImpl< std::pair< PHINode , Constant > > &	Res,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI
	)

static

Try to determine the resulting constant values in phi nodes at the common destination basic block, *CommonDest, for one of the case destionations CaseDest corresponding to value CaseVal (0 for the default case), of a switch instruction SI.

Definition at line 5933 of file SimplifyCFG.cpp.

References llvm::CallingConv::C, constantFold(), DL, llvm::Use::getUser(), I, Idx, llvm::BasicBlock::instructionsWithoutDebug(), lookupConstant(), PHI, and validLookupTableConstant().

Referenced by initializeUniqueCases(), and switchToLookupTable().

◆ getConstantInt()

static ConstantInt * getConstantInt	(	Value *	V,
		const DataLayout &	DL
	)

static

Extract ConstantInt from value, looking through IntToPtr and PointerNullValue.

Return NULL if value is not a constant int.

Definition at line 481 of file SimplifyCFG.cpp.

References llvm::ConstantFoldIntegerCast(), DL, and llvm::Value::getType().

◆ getKnownValueOnEdge()

static ConstantInt * getKnownValueOnEdge	(	Value *	V,
		BasicBlock *	From,
		BasicBlock *	To
	)

static

Definition at line 3308 of file SimplifyCFG.cpp.

References From, llvm::BranchInst::getCondition(), llvm::Value::getContext(), llvm::ConstantInt::getFalse(), llvm::BranchInst::getSuccessor(), llvm::ConstantInt::getTrue(), I, and llvm::BranchInst::isConditional().

Referenced by foldCondBranchOnValueKnownInPredecessorImpl().

◆ hoistLockstepIdenticalDbgVariableRecords()

static void hoistLockstepIdenticalDbgVariableRecords	(	Instruction *	TI,
		Instruction *	I1,
		SmallVectorImpl< Instruction * > &	OtherInsts
	)

static

Hoists DbgVariableRecords from I1 and OtherInstrs that are identical in lock-step to TI.

This matches how dbg.* intrinsics are hoisting in hoistCommonCodeFromSuccessors. e.g. The input: I1 DVRs: { x, z }, OtherInsts: { I2 DVRs: { x, y, z } } would result in hoisting only DbgVariableRecord x.

Definition at line 1535 of file SimplifyCFG.cpp.

References llvm::all_of(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), I, llvm::make_first_range(), llvm::none_of(), Other, llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::DbgRecord::removeFromParent(), llvm::SmallVectorImpl< T >::reserve(), and llvm::SmallVectorBase< Size_T >::size().

◆ incomingValuesAreCompatible()

static bool incomingValuesAreCompatible	(	BasicBlock *	BB,
		ArrayRef< BasicBlock * >	IncomingBlocks,
		SmallPtrSetImpl< Value * > *	EquivalenceSet = `nullptr`
	)

static

Return true if all the PHI nodes in the basic block BB receive compatible (identical) incoming values when coming from all of the predecessor blocks that are specified in IncomingBlocks.

Note that if the values aren't exactly identical, but EquivalenceSet is provided, and both of the values are present in the set, then they are considered equal.

Definition at line 317 of file SimplifyCFG.cpp.

References llvm::all_of(), assert(), llvm::BasicBlock::phis(), and llvm::ArrayRef< T >::size().

Referenced by safeToMergeTerminators().

◆ initializeUniqueCases()

static bool initializeUniqueCases	(	SwitchInst *	SI,
		PHINode *&	PHI,
		BasicBlock *&	CommonDest,
		SwitchCaseResultVectorTy &	UniqueResults,
		Constant *&	DefaultResult,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI,
		uintptr_t	MaxUniqueResults
	)

static

Definition at line 6022 of file SimplifyCFG.cpp.

References llvm::SmallVectorTemplateCommon< T, typename >::begin(), llvm::Function::begin(), DL, getCaseResults(), llvm::BasicBlock::getFirstNonPHIOrDbg(), I, mapCaseToResult(), MaxSwitchCasesPerResult, PHI, Results, llvm::SmallVectorBase< Size_T >::size(), and llvm::Function::size().

Referenced by trySwitchToSelect().

◆ isCleanupBlockEmpty()

static bool isCleanupBlockEmpty ( iterator_range< BasicBlock::iterator > R )

static

Definition at line 5044 of file SimplifyCFG.cpp.

References I, and II.

Referenced by removeEmptyCleanup().

◆ isLifeTimeMarker()

static bool isLifeTimeMarker ( const Instruction * I )

static

Definition at line 1928 of file SimplifyCFG.cpp.

References I, and II.

Referenced by canSinkInstructions().

◆ isProfitableToSpeculate()

static bool isProfitableToSpeculate	(	const BranchInst *	BI,
		bool	Invert,
		const TargetTransformInfo &	TTI
	)

static

Definition at line 2982 of file SimplifyCFG.cpp.

References llvm::extractBranchWeights(), llvm::BranchProbability::getBranchProbability(), llvm::Instruction::getMetadata(), and llvm::TargetTransformInfo::getPredictableBranchThreshold().

◆ isSafeToHoistInstr()

static bool isSafeToHoistInstr	(	Instruction *	I,
		unsigned	Flags
	)

static

Definition at line 1462 of file SimplifyCFG.cpp.

References I, llvm::isSafeToSpeculativelyExecute(), SkipImplicitControlFlow, SkipReadMem, and SkipSideEffect.

◆ isSafeToHoistInvoke()

static bool isSafeToHoistInvoke	(	BasicBlock *	BB1,
		BasicBlock *	BB2,
		Instruction *	I1,
		Instruction *	I2
	)

static

Definition at line 1424 of file SimplifyCFG.cpp.

References llvm::BasicBlock::phis(), and llvm::successors().

◆ isSafeToSpeculateStore()

static Value * isSafeToSpeculateStore	(	Instruction *	I,
		BasicBlock *	BrBB,
		BasicBlock *	StoreBB,
		BasicBlock *	EndBB
	)

static

Determine if we can hoist sink a sole store instruction out of a conditional block.

We are looking for code like the following: BrBB: store i32 add, i32* arrayidx2 ... // No other stores or function calls (we could be calling a memory ... // function). cmp = icmp ult x, y br i1 cmp, label EndBB, label ThenBB ThenBB: store i32 add5, i32* arrayidx2 br label EndBB EndBB: ... We are going to transform this into: BrBB: store i32 add, i32* arrayidx2 ... // cmp = icmp ult x, y add.add5 = select i1 cmp, i32 add, add5 store i32 add.add5, i32* arrayidx2 ...

Returns: The pointer to the value of the previous store if the store can be hoisted into the predecessor block. 0 otherwise.

Definition at line 2868 of file SimplifyCFG.cpp.

References llvm::StoreInst::getAlign(), llvm::StoreInst::getPointerOperand(), llvm::Value::getType(), llvm::getUnderlyingObject(), llvm::StoreInst::getValueOperand(), I, llvm::BasicBlock::instructionsWithoutDebug(), llvm::StoreInst::isSimple(), llvm::PointerMayBeCaptured(), and llvm::reverse().

◆ isSwitchDense() [1/2]

static bool isSwitchDense ( ArrayRef< int64_t > Values )

static

Definition at line 6514 of file SimplifyCFG.cpp.

References llvm::ArrayRef< T >::back(), llvm::ArrayRef< T >::front(), isSwitchDense(), Range, and llvm::ArrayRef< T >::size().

◆ isSwitchDense() [2/2]

static bool isSwitchDense	(	uint64_t	NumCases,
		uint64_t	CaseRange
	)

static

Definition at line 6502 of file SimplifyCFG.cpp.

References UINT64_MAX.

Referenced by isSwitchDense(), reduceSwitchRange(), shouldBuildLookupTable(), and simplifySwitchOfPowersOfTwo().

◆ isTypeLegalForLookupTable()

static bool isTypeLegalForLookupTable	(	Type *	Ty,
		const TargetTransformInfo &	TTI,
		const DataLayout &	DL
	)

static

Definition at line 6481 of file SimplifyCFG.cpp.

References llvm::BitWidth, DL, llvm::isPowerOf2_32(), llvm::TargetTransformInfo::isTypeLegal(), and IT.

Referenced by shouldBuildLookupTable().

◆ isVectorOp()

static bool isVectorOp ( Instruction & I )

static

Return if an instruction's type or any of its operands' types are a vector type.

Definition at line 3894 of file SimplifyCFG.cpp.

References llvm::any_of(), and I.

Referenced by llvm::foldBranchToCommonDest().

◆ lookupConstant()

static Constant * lookupConstant	(	Value *	V,
		const SmallDenseMap< Value , Constant > &	ConstantPool
	)

static

If V is a Constant, return it.

Otherwise, try to look up its constant value in ConstantPool, returning 0 if it's not there.

Definition at line 5892 of file SimplifyCFG.cpp.

References llvm::CallingConv::C.

Referenced by constantFold(), and getCaseResults().

◆ mapCaseToResult()

static size_t mapCaseToResult	(	ConstantInt *	CaseVal,
		SwitchCaseResultVectorTy &	UniqueResults,
		Constant *	Result
	)

static

Definition at line 6004 of file SimplifyCFG.cpp.

References I.

Referenced by initializeUniqueCases().

◆ mergeCleanupPad()

static bool mergeCleanupPad ( CleanupReturnInst * RI )

static

Definition at line 5275 of file SimplifyCFG.cpp.

References llvm::BranchInst::Create(), llvm::Instruction::eraseFromParent(), llvm::BasicBlock::front(), llvm::CleanupReturnInst::getCleanupPad(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BasicBlock::getSinglePredecessor(), llvm::CleanupReturnInst::getUnwindDest(), and llvm::Value::replaceAllUsesWith().

◆ mergeCompatibleInvokes()

static bool mergeCompatibleInvokes	(	BasicBlock *	BB,
		DomTreeUpdater *	DTU
	)

static

If this block is a landingpad exception handling block, categorize all the predecessor invokes into sets, with all invokes in each set being "mergeable" together, and then merge invokes in each set together.

This is a weird mix of hoisting and sinking. Visually, it goes from: [...] [...] | | [invoke0] [invoke1] / \ / \ [cont0] [landingpad] [cont1] to: [...] [...] \ / [invoke] / \ [cont] [landingpad]

But of course we can only do that if the invokes share the landingpad, edges invoke0->cont0 and invoke1->cont1 are "compatible", and the invoked functions are "compatible".

Definition at line 2785 of file SimplifyCFG.cpp.

References EnableMergeCompatibleInvokes, llvm::BasicBlock::isLandingPad(), mergeCompatibleInvokesImpl(), llvm::predecessors(), and llvm::ArrayRef< T >::size().

◆ mergeCompatibleInvokesImpl()

static void mergeCompatibleInvokesImpl	(	ArrayRef< InvokeInst * >	Invokes,
		DomTreeUpdater *	DTU
	)

static

Definition at line 2640 of file SimplifyCFG.cpp.

References assert(), llvm::Instruction::clone(), llvm::BasicBlock::Create(), llvm::BasicBlock::end(), llvm::ArrayRef< T >::front(), llvm::Value::getContext(), llvm::Value::getName(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BasicBlock::getParent(), II, llvm::Instruction::insertInto(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::SmallVectorImpl< T >::reserve(), llvm::InvokeInst::setNormalDest(), llvm::ArrayRef< T >::size(), and llvm::successors().

Referenced by mergeCompatibleInvokes().

◆ mergeConditionalStores()

static bool mergeConditionalStores	(	BranchInst *	PBI,
		BranchInst *	QBI,
		DomTreeUpdater *	DTU,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI
	)

static

Definition at line 4245 of file SimplifyCFG.cpp.

References DL, llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BasicBlock::getSinglePredecessor(), llvm::BasicBlock::getSingleSuccessor(), llvm::BranchInst::getSuccessor(), I, llvm::SmallPtrSetImpl< PtrType >::insert(), mergeConditionalStoreToAddress(), P, llvm::set_intersect(), and std::swap().

Referenced by SimplifyCondBranchToCondBranch().

◆ mergeConditionalStoreToAddress()

static bool mergeConditionalStoreToAddress	(	BasicBlock *	PTB,
		BasicBlock *	PFB,
		BasicBlock *	QTB,
		BasicBlock *	QFB,
		BasicBlock *	PostBB,
		Value *	Address,
		bool	InvertPCond,
		bool	InvertQCond,
		DomTreeUpdater *	DTU,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI
	)

static

Definition at line 4097 of file SimplifyCFG.cpp.

References assert(), llvm::IRBuilderBase::CreateNot(), llvm::IRBuilderBase::CreateOr(), llvm::IRBuilderBase::CreateStore(), ensureValueAvailableInSuccessor(), llvm::Instruction::eraseFromParent(), llvm::find(), findUniqueStoreInBlocks(), llvm::Instruction::getAAMetadata(), llvm::StoreInst::getAlign(), llvm::BasicBlock::getFirstInsertionPt(), llvm::IRBuilderBase::GetInsertPoint(), llvm::TargetTransformInfo::getInstructionCost(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BasicBlock::getSinglePredecessor(), llvm::BasicBlock::getTerminator(), llvm::Value::getType(), llvm::StoreInst::getValueOperand(), I, llvm::BasicBlock::instructionsWithoutDebug(), llvm::StoreInst::isUnordered(), llvm::AAMDNodes::merge(), MergeCondStoresAggressively, PHINodeFoldingThreshold, llvm::pred_begin(), llvm::pred_end(), llvm::IRBuilderBase::SetCurrentDebugLocation(), llvm::IRBuilderBase::SetInsertPoint(), llvm::SplitBlockAndInsertIfThen(), llvm::SplitBlockPredecessors(), llvm::TargetTransformInfo::TCC_Basic, and llvm::TargetTransformInfo::TCK_SizeAndLatency.

Referenced by mergeConditionalStores().

◆ mergeNestedCondBranch()

static bool mergeNestedCondBranch	(	BranchInst *	BI,
		DomTreeUpdater *	DTU
	)

static

Fold the following pattern: bb0: br i1 cond1, label bb1, label bb2 bb1: br i1 cond2, label bb3, label bb4 bb2: br i1 cond2, label bb4, label bb3 bb3: ... bb4: ... into bb0: cond = xor i1 cond1, cond2 br i1 cond, label bb4, label bb3 bb3: ... bb4: ... NOTE: cond2 always dominates the terminator of bb0.

Definition at line 7529 of file SimplifyCFG.cpp.

References llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), llvm::IRBuilderBase::CreateXor(), llvm::extractBranchWeights(), fitWeights(), llvm::BasicBlock::front(), llvm::BranchInst::getCondition(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::BasicBlock::removePredecessor(), setBranchWeights(), llvm::BranchInst::setCondition(), and llvm::BranchInst::setSuccessor().

◆ passingValueIsAlwaysUndefined()

static bool passingValueIsAlwaysUndefined	(	Value *	V,
		Instruction *	I,
		bool	PtrValueMayBeModified = `false`
	)

static

Check if passing a value to an instruction will cause undefined behavior.

Definition at line 7713 of file SimplifyCFG.cpp.

References llvm::any_of(), llvm::CallingConv::C, llvm::find_if(), GEP, I, llvm::isGuaranteedToTransferExecutionToSuccessor(), llvm::make_range(), llvm::NullPointerIsDefined(), and passingValueIsAlwaysUndefined().

Referenced by passingValueIsAlwaysUndefined(), removeUndefIntroducingPredecessor(), and validateAndCostRequiredSelects().

◆ performBranchToCommonDestFolding()

static bool performBranchToCommonDestFolding	(	BranchInst *	BI,
		BranchInst *	PBI,
		DomTreeUpdater *	DTU,
		MemorySSAUpdater *	MSSAU,
		const TargetTransformInfo *	TTI
	)

static

Definition at line 3780 of file SimplifyCFG.cpp.

References addPredecessorToBlock(), llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), llvm::SmallVectorTemplateCommon< T, typename >::begin(), llvm::Instruction::cloneDebugInfoFrom(), cloneInstructionsIntoPredecessorBlockAndUpdateSSAUses(), llvm::IRBuilderBase::CollectMetadataToCopy(), createLogicalOp(), llvm::dbgs(), llvm::SmallVectorTemplateCommon< T, typename >::end(), extractPredSuccWeights(), llvm::filterDbgVars(), fitWeights(), llvm::BranchInst::getCondition(), llvm::Instruction::getDbgRecordRange(), llvm::Instruction::getMetadata(), llvm::BasicBlock::getModule(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::InvertBranch(), llvm::BasicBlock::IsNewDbgInfoFormat, LLVM_DEBUG, llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::RemapDbgRecord(), llvm::RF_IgnoreMissingLocals, llvm::RF_NoModuleLevelChanges, setBranchWeights(), llvm::BranchInst::setCondition(), llvm::Instruction::setMetadata(), llvm::BranchInst::setSuccessor(), and shouldFoldCondBranchesToCommonDestination().

Referenced by llvm::foldBranchToCommonDest().

◆ reduceSwitchRange()

static bool reduceSwitchRange	(	SwitchInst *	SI,
		IRBuilder<> &	Builder,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI
	)

static

Try to transform a switch that has "holes" in it to a contiguous sequence of cases.

A switch such as: switch(i) {case 5: case 9: case 13: case 17:} can be range-reduced to: switch ((i-5) / 4) {case 0: case 1: case 2: case 3:}.

This converts a sparse switch into a dense switch which allows better lowering and could also allow transforming into a lookup table.

Definition at line 6981 of file SimplifyCFG.cpp.

References assert(), llvm::sampleprof::Base, llvm::CallingConv::C, llvm::countr_zero(), llvm::IRBuilderBase::CreateIntrinsic(), llvm::IRBuilderBase::CreateSub(), DL, isSwitchDense(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::IRBuilderBase::SetInsertPoint(), and llvm::sort().

◆ removeEmptyCleanup()

static bool removeEmptyCleanup	(	CleanupReturnInst *	RI,
		DomTreeUpdater *	DTU
	)

static

Definition at line 5157 of file SimplifyCFG.cpp.

References llvm::PHINode::addIncoming(), llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), assert(), llvm::DeleteDeadBlock(), llvm::PoisonValue::get(), llvm::CleanupReturnInst::getCleanupPad(), llvm::BasicBlock::getFirstNonPHI(), llvm::PHINode::getIncomingValueForBlock(), llvm::ilist_node_with_parent< NodeTy, ParentTy, Options >::getNextNode(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::Value::getType(), llvm::CleanupReturnInst::getUnwindDest(), llvm::Value::hasOneUse(), Idx, isCleanupBlockEmpty(), llvm::Instruction::isUsedOutsideOfBlock(), llvm::make_early_inc_range(), llvm::Instruction::moveBefore(), llvm::BasicBlock::phis(), pred, llvm::predecessors(), llvm::BasicBlock::removePredecessor(), llvm::removeUnwindEdge(), llvm::User::replaceUsesOfWith(), and llvm::Value::use_empty().

◆ removeSwitchAfterSelectFold()

static void removeSwitchAfterSelectFold	(	SwitchInst *	SI,
		PHINode *	PHI,
		Value *	SelectValue,
		IRBuilder<> &	Builder,
		DomTreeUpdater *	DTU
	)

static

Definition at line 6155 of file SimplifyCFG.cpp.

References llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), llvm::IRBuilderBase::CreateBr(), Idx, llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::is_contained(), PHI, llvm::predecessors(), and llvm::BasicBlock::removePredecessor().

Referenced by trySwitchToSelect().

◆ removeUndefIntroducingPredecessor()

static bool removeUndefIntroducingPredecessor	(	BasicBlock *	BB,
		DomTreeUpdater *	DTU,
		AssumptionCache *	AC
	)

static

If BB has an incoming value that will always trigger undefined behavior (eg.

null pointer dereference), remove the branch leading here.

Definition at line 7845 of file SimplifyCFG.cpp.

References llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), Cond, llvm::BasicBlock::Create(), llvm::IRBuilderBase::CreateAssumption(), llvm::IRBuilderBase::CreateBr(), llvm::IRBuilderBase::CreateNot(), llvm::IRBuilderBase::CreateUnreachable(), llvm::Instruction::eraseFromParent(), llvm::BranchInst::getCondition(), llvm::BasicBlock::getContext(), llvm::BasicBlock::getParent(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::BranchInst::isUnconditional(), passingValueIsAlwaysUndefined(), PHI, llvm::BasicBlock::phis(), llvm::AssumptionCache::registerAssumption(), llvm::BasicBlock::removePredecessor(), and llvm::IRBuilderBase::SetInsertPoint().

◆ replacingOperandWithVariableIsCheap()

static bool replacingOperandWithVariableIsCheap	(	const Instruction *	I,
		int	OpIdx
	)

static

Definition at line 1943 of file SimplifyCFG.cpp.

References I.

Referenced by canSinkInstructions().

◆ reuseTableCompare()

static void reuseTableCompare	(	User *	PhiUser,
		BasicBlock *	PhiBlock,
		BranchInst *	RangeCheckBranch,
		Constant *	DefaultValue,
		const SmallVectorImpl< std::pair< ConstantInt , Constant > > &	Values
	)

static

Try to reuse the switch table index compare.

Following pattern:

if (idx < tablesize)
   r = table[idx]; // table does not contain default_value
else
   r = default_value;
if (r != default_value)
   ...

Is optimized to:

cond = idx < tablesize;
if (cond)
   r = table[idx];
else
   r = default_value;
if (cond)
   ...

Jump threading will then eliminate the second if(cond).

Definition at line 6603 of file SimplifyCFG.cpp.

References llvm::ConstantFoldCompareInstOperands(), DL, llvm::BranchInst::getCondition(), llvm::BasicBlock::getDataLayout(), llvm::ConstantInt::getFalse(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::User::getOperand(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::CmpInst::getPredicate(), llvm::ConstantInt::getTrue(), llvm::Value::getType(), llvm::BasicBlock::getUniquePredecessor(), llvm::predecessors(), and llvm::Value::replaceAllUsesWith().

Referenced by switchToLookupTable().

◆ safeToMergeTerminators()

static bool safeToMergeTerminators	(	Instruction *	SI1,
		Instruction *	SI2,
		SmallSetVector< BasicBlock , 4 >	FailBlocks = `nullptr`
	)

static

Return true if it is safe to merge these two terminator instructions together.

Definition at line 341 of file SimplifyCFG.cpp.

References llvm::SmallPtrSetImpl< PtrType >::count(), Fail, llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), incomingValuesAreCompatible(), llvm::succ_begin(), llvm::succ_end(), and llvm::successors().

Referenced by llvm::foldBranchToCommonDest().

◆ setBranchWeights() [1/2]

static void setBranchWeights	(	Instruction *	I,
		uint32_t	TrueWeight,
		uint32_t	FalseWeight,
		bool	IsExpected
	)

static

Definition at line 877 of file SimplifyCFG.cpp.

References assert(), llvm::MDBuilder::createBranchWeights(), I, and N.

◆ setBranchWeights() [2/2]

static void setBranchWeights	(	SwitchInst *	SI,
		ArrayRef< uint32_t >	Weights,
		bool	IsExpected
	)

static

Definition at line 864 of file SimplifyCFG.cpp.

References llvm::any_of(), llvm::MDBuilder::createBranchWeights(), and N.

Referenced by mergeNestedCondBranch(), performBranchToCommonDestFolding(), and SimplifyCondBranchToCondBranch().

◆ shouldBuildLookupTable()

static bool shouldBuildLookupTable	(	SwitchInst *	SI,
		uint64_t	TableSize,
		const TargetTransformInfo &	TTI,
		const DataLayout &	DL,
		const SmallDenseMap< PHINode , Type > &	ResultTypes
	)

static

Determine whether a lookup table should be built for this switch, based on the number of cases, size of the table, and the types of the results.

Definition at line 6529 of file SimplifyCFG.cpp.

References DL, I, isSwitchDense(), and isTypeLegalForLookupTable().

Referenced by switchToLookupTable().

◆ shouldFoldCondBranchesToCommonDestination()

static std::optional< std::tuple< BasicBlock *, Instruction::BinaryOps, bool > > shouldFoldCondBranchesToCommonDestination	(	BranchInst *	BI,
		BranchInst *	PBI,
		const TargetTransformInfo *	TTI
	)

static

Determine if the two branches share a common destination and deduce a glue that joins the branches' conditions to arrive at the common destination if that would be profitable.

Definition at line 3741 of file SimplifyCFG.cpp.

References assert(), llvm::extractBranchWeights(), llvm::BranchProbability::getBranchProbability(), llvm::BranchProbability::getCompl(), llvm::Instruction::getMetadata(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::TargetTransformInfo::getPredictableBranchThreshold(), llvm::BranchInst::getSuccessor(), llvm::is_contained(), llvm::BranchInst::isConditional(), llvm::BranchProbability::isUnknown(), and llvm::predecessors().

Referenced by llvm::foldBranchToCommonDest(), and performBranchToCommonDestFolding().

◆ shouldHoistCommonInstructions()

static bool shouldHoistCommonInstructions	(	Instruction *	I1,
		Instruction *	I2,
		const TargetTransformInfo &	TTI
	)

static

Helper function for hoistCommonCodeFromSuccessors.

Return true if identical instructions I1 and I2 can and should be hoisted.

Definition at line 1500 of file SimplifyCFG.cpp.

References llvm::TargetTransformInfo::isProfitableToHoist().

◆ shouldUseSwitchConditionAsTableIndex()

static bool shouldUseSwitchConditionAsTableIndex	(	ConstantInt &	MinCaseVal,
		const ConstantInt &	MaxCaseVal,
		bool	HasDefaultResults,
		const SmallDenseMap< PHINode , Type > &	ResultTypes,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI
	)

static

Definition at line 6566 of file SimplifyCFG.cpp.

References llvm::all_of(), DL, llvm::ConstantInt::getLimitedValue(), llvm::ConstantInt::isNegative(), and llvm::Constant::isNullValue().

Referenced by switchToLookupTable().

◆ SimplifyCondBranchToCondBranch()

static bool SimplifyCondBranchToCondBranch	(	BranchInst *	PBI,
		BranchInst *	BI,
		DomTreeUpdater *	DTU,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI
	)

static

If we have a conditional branch as a predecessor of another block, this function tries to simplify it.

We know that PBI and BI are both conditional branches, and BI is in one of the successor blocks of PBI - PBI branches to BI.

Definition at line 4414 of file SimplifyCFG.cpp.

References addPredecessorToBlock(), llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), assert(), llvm::BasicBlock::begin(), Cond, llvm::BranchInst::Create(), llvm::BasicBlock::Create(), createLogicalOp(), llvm::IRBuilderBase::CreateNot(), llvm::IRBuilderBase::CreateSelect(), llvm::dbgs(), DL, llvm::extractBranchWeights(), extractPredSuccWeights(), fitWeights(), llvm::PHINode::getBasicBlockIndex(), llvm::BranchProbability::getBranchProbability(), llvm::BranchInst::getCondition(), llvm::BasicBlock::getContext(), llvm::PHINode::getIncomingValue(), llvm::PHINode::getIncomingValueForBlock(), llvm::Type::getInt1Ty(), llvm::Instruction::getMetadata(), llvm::Value::getName(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BasicBlock::getParent(), llvm::TargetTransformInfo::getPredictableBranchThreshold(), llvm::BasicBlock::getSinglePredecessor(), llvm::BranchInst::getSuccessor(), II, llvm::BasicBlock::instructionsWithoutDebug(), llvm::BranchInst::isConditional(), LLVM_DEBUG, mergeConditionalStores(), MergeCondStores, llvm::BasicBlock::phis(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), setBranchWeights(), llvm::BranchInst::setCondition(), llvm::PHINode::setIncomingValue(), llvm::BranchInst::setSuccessor(), and tryWidenCondBranchToCondBranch().

◆ simplifySwitchOfCmpIntrinsic()

static bool simplifySwitchOfCmpIntrinsic	(	SwitchInst *	SI,
		IRBuilderBase &	Builder,
		DomTreeUpdater *	DTU
	)

static

Fold switch over ucmp/scmp intrinsic to br if two of the switch arms have the same destination.

Definition at line 7136 of file SimplifyCFG.cpp.

References llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), assert(), llvm::MDBuilder::createBranchWeights(), llvm::IRBuilderBase::CreateCondBr(), llvm::IRBuilderBase::CreateICmp(), llvm::extractBranchWeights(), llvm::getBranchWeightMDNode(), llvm::ICmpInst::getSignedPredicate(), OtherSucc(), llvm::BasicBlock::removePredecessor(), llvm::SmallVectorImpl< T >::resize(), llvm::IRBuilderBase::SetInsertPoint(), std::swap(), and llvm::APInt::trySExtValue().

◆ simplifySwitchOfPowersOfTwo()

static bool simplifySwitchOfPowersOfTwo	(	SwitchInst *	SI,
		IRBuilder<> &	Builder,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI
	)

static

Tries to transform switch of powers of two to reduce switch range.

For example, switch like: switch (C) { case 1: case 2: case 64: case 128: } will be transformed to: switch (count_trailing_zeros(C)) { case 0: case 1: case 6: case 7: }

This transformation allows better lowering and could allow transforming into a lookup table.

Definition at line 7068 of file SimplifyCFG.cpp.

References llvm::SmallVectorTemplateCommon< T, typename >::back(), llvm::countr_zero(), llvm::IRBuilderBase::CreateIntrinsic(), DL, llvm::SmallVectorTemplateCommon< T, typename >::front(), llvm::TargetTransformInfo::getIntrinsicInstrCost(), llvm::ConstantInt::getTrue(), llvm::Value::getType(), llvm::has_single_bit(), isSwitchDense(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::IRBuilderBase::SetInsertPoint(), llvm::SmallVectorBase< Size_T >::size(), llvm::sort(), llvm::TargetTransformInfo::TCC_Basic, and llvm::TargetTransformInfo::TCK_SizeAndLatency.

◆ sinkCommonCodeFromPredecessors()

static bool sinkCommonCodeFromPredecessors	(	BasicBlock *	BB,
		DomTreeUpdater *	DTU
	)

static

Check whether BB's predecessors end with unconditional branches.

If it is true, sink any common code from the predecessors to BB.

Definition at line 2255 of file SimplifyCFG.cpp.

References llvm::all_of(), assert(), canSinkInstructions(), llvm::dbgs(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::end(), llvm::SmallPtrSetImpl< PtrType >::erase(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::find(), I, Idx, llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::insert(), llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::IsBlockFollowedByDeoptOrUnreachable(), llvm::isSafeToSpeculativelyExecute(), LLVM_DEBUG, llvm::BasicBlock::phis(), llvm::predecessors(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), sinkLastInstruction(), llvm::SmallVectorBase< Size_T >::size(), and llvm::SplitBlockPredecessors().

◆ sinkLastInstruction()

static void sinkLastInstruction ( ArrayRef< BasicBlock * > Blocks )

static

◆ skippedInstrFlags()

static unsigned skippedInstrFlags ( Instruction * I )

static

Definition at line 1447 of file SimplifyCFG.cpp.

References I, llvm::isGuaranteedToTransferExecutionToSuccessor(), SkipImplicitControlFlow, SkipReadMem, and SkipSideEffect.

◆ STATISTIC() [1/15]

STATISTIC	(	NumBitMaps	,
		"Number of switch instructions turned into bitmaps"
	)

◆ STATISTIC() [2/15]

STATISTIC	(	NumFoldBranchToCommonDest	,
		"Number of branches folded into predecessor basic block"
	)

◆ STATISTIC() [3/15]

STATISTIC	(	NumFoldValueComparisonIntoPredecessors	,
		"Number of value comparisons folded into predecessor basic blocks"
	)

◆ STATISTIC() [4/15]

STATISTIC	(	NumHoistCommonCode	,
		"Number of common instruction 'blocks' hoisted up to the begin block"
	)

◆ STATISTIC() [5/15]

STATISTIC	(	NumHoistCommonInstrs	,
		"Number of common instructions hoisted up to the begin block"
	)

◆ STATISTIC() [6/15]

STATISTIC	(	NumInvokes	,
		"Number of invokes with empty resume blocks simplified into calls"
	)

◆ STATISTIC() [7/15]

STATISTIC	(	NumInvokeSetsFormed	,
		"Number of invoke sets that were formed"
	)

◆ STATISTIC() [8/15]

STATISTIC	(	NumInvokesMerged	,
		"Number of invokes that were merged together"
	)

◆ STATISTIC() [9/15]

STATISTIC	(	NumLinearMaps	,
		"Number of switch instructions turned into linear mapping"
	)

◆ STATISTIC() [10/15]

STATISTIC	(	NumLookupTables	,
		"Number of switch instructions turned into lookup tables"
	)

◆ STATISTIC() [11/15]

STATISTIC	(	NumLookupTablesHoles	,
		"Number of switch instructions turned into lookup tables (holes checked)"
	)

◆ STATISTIC() [12/15]

STATISTIC	(	NumSinkCommonCode	,
		"Number of common instruction 'blocks' sunk down to the end block"
	)

◆ STATISTIC() [13/15]

STATISTIC	(	NumSinkCommonInstrs	,
		"Number of common instructions sunk down to the end block"
	)

◆ STATISTIC() [14/15]

STATISTIC	(	NumSpeculations	,
		"Number of speculative executed instructions"
	)

◆ STATISTIC() [15/15]

STATISTIC	(	NumTableCmpReuses	,
		"Number of reused switch table lookup compares"
	)

◆ switchToLookupTable()

static bool switchToLookupTable	(	SwitchInst *	SI,
		IRBuilder<> &	Builder,
		DomTreeUpdater *	DTU,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI
	)

static

If the switch is only used to initialize one or more phi nodes in a common successor block with different constant values, replace the switch with lookup tables.

Definition at line 6668 of file SimplifyCFG.cpp.

◆ trySwitchToSelect()

static bool trySwitchToSelect	(	SwitchInst *	SI,
		IRBuilder<> &	Builder,
		DomTreeUpdater *	DTU,
		const DataLayout &	DL,
		const TargetTransformInfo &	TTI
	)

static

If a switch is only used to initialize one or more phi nodes in a common successor block with only two different constant values, try to replace the switch with a select.

Returns true if the fold was made.

Definition at line 6192 of file SimplifyCFG.cpp.

References assert(), Cond, DL, foldSwitchToSelect(), initializeUniqueCases(), PHI, removeSwitchAfterSelectFold(), and llvm::IRBuilderBase::SetInsertPoint().

◆ tryToMergeLandingPad()

static bool tryToMergeLandingPad	(	LandingPadInst *	LPad,
		BranchInst *	BI,
		BasicBlock *	BB,
		DomTreeUpdater *	DTU
	)

static

Given an block with only a single landing pad and a unconditional branch try to find another basic block which this one can be merged with.

This handles cases where we have multiple invokes with unique landing pads, but a shared handler.

We specifically choose to not worry about merging non-empty blocks here. That is a PRE/scheduling problem and is best solved elsewhere. In practice, the optimizer produces empty landing pad blocks quite frequently when dealing with exception dense code. (see: instcombine, gvn, if-else sinking in this file)

This is primarily a code size optimization. We need to avoid performing any transform which might inhibit optimization (such as our ability to specialize a particular handler via tail commoning). We do this by not merging any blocks which require us to introduce a phi. Since the same values are flowing through both blocks, we don't lose any ability to specialize. If anything, we make such specialization more likely.

TODO - This transformation could remove entries from a phi in the target block when the inputs in the phi are the same for the two blocks being merged. In some cases, this could result in removal of the PHI entirely.

Definition at line 7380 of file SimplifyCFG.cpp.

References llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), assert(), llvm::BasicBlock::begin(), llvm::IRBuilderBase::CreateUnreachable(), llvm::Instruction::eraseFromParent(), llvm::BasicBlock::getTerminator(), llvm::BasicBlock::getUniqueSuccessor(), I, II, llvm::Instruction::isIdenticalTo(), llvm::make_early_inc_range(), llvm::pred_begin(), llvm::pred_end(), llvm::predecessors(), llvm::BasicBlock::removePredecessor(), llvm::succ_begin(), and llvm::succ_end().

◆ tryWidenCondBranchToCondBranch()

static bool tryWidenCondBranchToCondBranch	(	BranchInst *	PBI,
		BranchInst *	BI,
		DomTreeUpdater *	DTU
	)

static

If the previous block ended with a widenable branch, determine if reusing the target block is profitable and legal.

This will have the effect of "widening" PBI, but doesn't require us to reason about hosting safety.

Definition at line 4357 of file SimplifyCFG.cpp.

References llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdates(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminatingDeoptimizeCall(), I, llvm::isWidenableBranch(), llvm::none_of(), llvm::BasicBlock::phis(), llvm::BasicBlock::removePredecessor(), llvm::BranchInst::setSuccessor(), and llvm::succ_empty().

Referenced by SimplifyCondBranchToCondBranch().

◆ validateAndCostRequiredSelects()

static bool validateAndCostRequiredSelects	(	BasicBlock *	BB,
		BasicBlock *	ThenBB,
		BasicBlock *	EndBB,
		unsigned &	SpeculatedInstructions,
		InstructionCost &	Cost,
		const TargetTransformInfo &	TTI
	)

static

Estimate the cost of the insertion(s) and check that the PHI nodes can be converted to selects.

Definition at line 2929 of file SimplifyCFG.cpp.

References llvm::CmpInst::BAD_ICMP_PREDICATE, computeSpeculationCost(), CostKind, llvm::TargetTransformInfo::getCmpSelInstrCost(), llvm::PHINode::getIncomingValueForBlock(), llvm::BasicBlock::getParent(), llvm::Value::getType(), llvm::Function::hasMinSize(), passingValueIsAlwaysUndefined(), PHINodeFoldingThreshold, llvm::BasicBlock::phis(), llvm::TargetTransformInfo::TCC_Basic, llvm::TargetTransformInfo::TCK_CodeSize, and llvm::TargetTransformInfo::TCK_SizeAndLatency.

◆ validLookupTableConstant()

static bool validLookupTableConstant	(	Constant *	C,
		const TargetTransformInfo &	TTI
	)

static

Return true if the backend will be able to handle initializing an array of constants like C.

Definition at line 5864 of file SimplifyCFG.cpp.

References llvm::CallingConv::C, llvm::TargetTransformInfo::shouldBuildLookupTablesForConstant(), and validLookupTableConstant().

Referenced by getCaseResults(), and validLookupTableConstant().

◆ valuesOverlap()

static bool valuesOverlap	(	std::vector< ValueEqualityComparisonCase > &	C1,
		std::vector< ValueEqualityComparisonCase > &	C2
	)

static

Return true if there are any keys in C1 that exist in C2 as well.

Definition at line 829 of file SimplifyCFG.cpp.

References llvm::array_pod_sort(), std::swap(), and llvm::Value::Value().

Variable Documentation

◆ BranchFoldThreshold

cl::opt< unsigned > BranchFoldThreshold("simplifycfg-branch-fold-threshold", cl::Hidden, cl::init(2), cl::desc("Maximum cost of combining conditions when " "folding branches"))	(	"simplifycfg-branch-fold-threshold"	,
		cl::Hidden	,
		cl::init(2)	,
		cl::desc("Maximum cost of combining conditions when " "folding branches")
	)

static

Referenced by llvm::foldBranchToCommonDest().

◆ BranchFoldToCommonDestVectorMultiplier

cl::opt< unsigned > BranchFoldToCommonDestVectorMultiplier("simplifycfg-branch-fold-common-dest-vector-multiplier", cl::Hidden, cl::init(2), cl::desc("Multiplier to apply to threshold when determining whether or not " "to fold branch to common destination when vector operations are " "present"))	(	"simplifycfg-branch-fold-common-dest-vector-multiplier"	,
		cl::Hidden	,
		cl::init(2)	,
		cl::desc("Multiplier to apply to threshold when determining whether or not " "to fold branch to common destination when vector operations are " "present")
	)

static

Referenced by llvm::foldBranchToCommonDest().

◆ EnableMergeCompatibleInvokes

cl::opt< bool > EnableMergeCompatibleInvokes("simplifycfg-merge-compatible-invokes", cl::Hidden, cl::init(true), cl::desc("Allow SimplifyCFG to merge invokes together when appropriate"))	(	"simplifycfg-merge-compatible-invokes"	,
		cl::Hidden	,
		cl::init(true)	,
		cl::desc("Allow SimplifyCFG to merge invokes together when appropriate")
	)

static

Referenced by mergeCompatibleInvokes().

◆ HoistCommon

cl::opt< bool > HoistCommon("simplifycfg-hoist-common", cl::Hidden, cl::init(true), cl::desc("Hoist common instructions up to the parent block"))	(	"simplifycfg-hoist-common"	,
		cl::Hidden	,
		cl::init(true)	,
		cl::desc("Hoist common instructions up to the parent block")
	)

static

◆ HoistCommonSkipLimit

cl::opt< unsigned > HoistCommonSkipLimit("simplifycfg-hoist-common-skip-limit", cl::Hidden, cl::init(20), cl::desc("Allow reordering across at most this many " "instructions when hoisting"))	(	"simplifycfg-hoist-common-skip-limit"	,
		cl::Hidden	,
		cl::init(20)	,
		cl::desc("Allow reordering across at most this many " "instructions when hoisting")
	)

static

◆ HoistCondStores

cl::opt< bool > HoistCondStores("simplifycfg-hoist-cond-stores", cl::Hidden, cl::init(true), cl::desc("Hoist conditional stores if an unconditional store precedes"))	(	"simplifycfg-hoist-cond-stores"	,
		cl::Hidden	,
		cl::init(true)	,
		cl::desc("Hoist conditional stores if an unconditional store precedes")
	)

static

◆ MaxSmallBlockSize

cl::opt< int > MaxSmallBlockSize("simplifycfg-max-small-block-size", cl::Hidden, cl::init(10), cl::desc("Max size of a block which is still considered " "small enough to thread through"))	(	"simplifycfg-max-small-block-size"	,
		cl::Hidden	,
		cl::init(10)	,
		cl::desc("Max size of a block which is still considered " "small enough to thread through")
	)

static

Referenced by blockIsSimpleEnoughToThreadThrough().

◆ MaxSpeculationDepth

cl::opt< unsigned > MaxSpeculationDepth("max-speculation-depth", cl::Hidden, cl::init(10), cl::desc("Limit maximum recursion depth when calculating costs of " "speculatively executed instructions"))	(	"max-speculation-depth"	,
		cl::Hidden	,
		cl::init(10)	,
		cl::desc("Limit maximum recursion depth when calculating costs of " "speculatively executed instructions")
	)

static

Referenced by dominatesMergePoint().

◆ MaxSwitchCasesPerResult

cl::opt< unsigned > MaxSwitchCasesPerResult("max-switch-cases-per-result", cl::Hidden, cl::init(16), cl::desc("Limit cases to analyze when converting a switch to select"))	(	"max-switch-cases-per-result"	,
		cl::Hidden	,
		cl::init(16)	,
		cl::desc("Limit cases to analyze when converting a switch to select")
	)

static

Referenced by initializeUniqueCases().

◆ MergeCondStores

cl::opt< bool > MergeCondStores("simplifycfg-merge-cond-stores", cl::Hidden, cl::init(true), cl::desc("Hoist conditional stores even if an unconditional store does not " "precede - hoist multiple conditional stores into a single " "predicated store"))	(	"simplifycfg-merge-cond-stores"	,
		cl::Hidden	,
		cl::init(true)	,
		cl::desc("Hoist conditional stores even if an unconditional store does not " "precede - hoist multiple conditional stores into a single " "predicated store")
	)

static

Referenced by SimplifyCondBranchToCondBranch().

◆ MergeCondStoresAggressively

cl::opt< bool > MergeCondStoresAggressively("simplifycfg-merge-cond-stores-aggressively", cl::Hidden, cl::init(false), cl::desc("When merging conditional stores, do so even if the resultant " "basic blocks are unlikely to be if-converted as a result"))	(	"simplifycfg-merge-cond-stores-aggressively"	,
		cl::Hidden	,
		cl::init(false)	,
		cl::desc("When merging conditional stores, do so even if the resultant " "basic blocks are unlikely to be if-converted as a result")
	)

static

Referenced by mergeConditionalStoreToAddress().

◆ PHINodeFoldingThreshold

cl::opt< unsigned > PHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(2), cl::desc( "Control the amount of phi node folding to perform (default = 2)"))	(	"phi-node-folding-threshold"	,
		cl::Hidden	,
		cl::init(2)	,
		cl::desc( "Control the amount of phi node folding to perform (default = 2)")
	)

static

Referenced by mergeConditionalStoreToAddress(), and validateAndCostRequiredSelects().

◆ SinkCommon

cl::opt< bool > SinkCommon("simplifycfg-sink-common", cl::Hidden, cl::init(true), cl::desc("Sink common instructions down to the end block"))	(	"simplifycfg-sink-common"	,
		cl::Hidden	,
		cl::init(true)	,
		cl::desc("Sink common instructions down to the end block")
	)

static

◆ SpeculateOneExpensiveInst

cl::opt< bool > SpeculateOneExpensiveInst("speculate-one-expensive-inst", cl::Hidden, cl::init(true), cl::desc("Allow exactly one expensive instruction to be speculatively " "executed"))	(	"speculate-one-expensive-inst"	,
		cl::Hidden	,
		cl::init(true)	,
		cl::desc("Allow exactly one expensive instruction to be speculatively " "executed")
	)

static

Referenced by dominatesMergePoint().

◆ TwoEntryPHINodeFoldingThreshold

cl::opt< unsigned > TwoEntryPHINodeFoldingThreshold("two-entry-phi-node-folding-threshold", cl::Hidden, cl::init(4), cl::desc("Control the maximal total instruction cost that we are willing " "to speculatively execute to fold a 2-entry PHI node into a " "select (default = 4)"))	(	"two-entry-phi-node-folding-threshold"	,
		cl::Hidden	,
		cl::init(4)	,
		cl::desc("Control the maximal total instruction cost that we are willing " "to speculatively execute to fold a 2-entry PHI node into a " "select (default = 4)")
	)

static

Referenced by foldTwoEntryPHINode().

Macros

Enumerations

Functions

Variables

Macro Definition Documentation

◆ DEBUG_TYPE

Enumeration Type Documentation

◆ SkipFlags

Function Documentation

◆ addPredecessorToBlock()

◆ allPredecessorsComeFromSameSource()

◆ areIdenticalUpToCommutativity()

◆ blockIsSimpleEnoughToThreadThrough()

◆ canSinkInstructions()

◆ casesAreContiguous()

◆ cloneInstructionsIntoPredecessorBlockAndUpdateSSAUses()

◆ computeSpeculationCost()

◆ constantFold()

◆ constantIntSortPredicate()

◆ createLogicalOp()

◆ createUnreachableSwitchDefault()

◆ dominatesMergePoint()

◆ eliminateBlockCases()

◆ eliminateDeadSwitchCases()

◆ ensureValueAvailableInSuccessor()

◆ eraseTerminatorAndDCECond()

◆ extractPredSuccWeights()

◆ findPHIForConditionForwarding()

◆ findUniqueStoreInBlocks()

◆ fitWeights()

◆ foldCondBranchOnValueKnownInPredecessor()

◆ foldCondBranchOnValueKnownInPredecessorImpl()

◆ foldSwitchToSelect()

◆ foldTwoEntryPHINode()

◆ forwardSwitchConditionToPHI()

◆ getBranchWeights()

◆ getCaseResults()

◆ getConstantInt()

◆ getKnownValueOnEdge()

◆ hoistLockstepIdenticalDbgVariableRecords()

◆ incomingValuesAreCompatible()

◆ initializeUniqueCases()

◆ isCleanupBlockEmpty()

◆ isLifeTimeMarker()

◆ isProfitableToSpeculate()

◆ isSafeToHoistInstr()

◆ isSafeToHoistInvoke()

◆ isSafeToSpeculateStore()

◆ isSwitchDense() [1/2]

◆ isSwitchDense() [2/2]

◆ isTypeLegalForLookupTable()

◆ isVectorOp()

◆ lookupConstant()

◆ mapCaseToResult()

◆ mergeCleanupPad()

◆ mergeCompatibleInvokes()

◆ mergeCompatibleInvokesImpl()

◆ mergeConditionalStores()

◆ mergeConditionalStoreToAddress()

◆ mergeNestedCondBranch()

◆ passingValueIsAlwaysUndefined()

◆ performBranchToCommonDestFolding()

◆ reduceSwitchRange()

◆ removeEmptyCleanup()

◆ removeSwitchAfterSelectFold()

◆ removeUndefIntroducingPredecessor()

◆ replacingOperandWithVariableIsCheap()

◆ reuseTableCompare()

◆ safeToMergeTerminators()

◆ setBranchWeights() [1/2]

◆ setBranchWeights() [2/2]

◆ shouldBuildLookupTable()

◆ shouldFoldCondBranchesToCommonDestination()

◆ shouldHoistCommonInstructions()

◆ shouldUseSwitchConditionAsTableIndex()

◆ SimplifyCondBranchToCondBranch()

◆ simplifySwitchOfCmpIntrinsic()

◆ simplifySwitchOfPowersOfTwo()

◆ sinkCommonCodeFromPredecessors()

◆ sinkLastInstruction()