#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.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/ConstantFolding.h"
#include "llvm/Analysis/EHPersonalities.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/CallSite.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.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/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.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/Type.h"
#include "llvm/IR/Use.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.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 <set>
#include <tuple>
#include <utility>
#include <vector>

Macros
#define	DEBUG_TYPE "simplifycfg"

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

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

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. More...

static bool	isProfitableToFoldUnconditional (BranchInst SI1, BranchInst SI2, Instruction Cond, SmallVectorImpl< PHINode > &PhiNodes)
	Return true if it is safe and profitable to merge these two terminator instructions together, where SI1 is an unconditional branch. More...

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. More...

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

static bool	DominatesMergePoint (Value V, BasicBlock BB, SmallPtrSetImpl< Instruction *> &AggressiveInsts, int &BudgetRemaining, 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. More...

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

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. More...

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. More...

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

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

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

static bool	HasBranchWeights (const Instruction *I)

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. More...

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

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

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

static bool	HoistThenElseCodeToIf (BranchInst *BI, const TargetTransformInfo &TTI)
	Given a conditional branch that goes to BB1 and BB2, hoist any common code in the two blocks up into the branch block. More...

static bool	isLifeTimeMarker (const Instruction *I)

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

static bool	sinkLastInstruction (ArrayRef< BasicBlock *> Blocks)

static bool	SinkCommonCodeFromPredecessors (BasicBlock *BB)
	Check whether BB's predecessors end with unconditional branches. More...

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. More...

static bool	SpeculativelyExecuteBB (BranchInst BI, BasicBlock ThenBB, const TargetTransformInfo &TTI)
	Speculate a conditional basic block flattening the CFG. More...

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

static bool	FoldCondBranchOnPHI (BranchInst BI, const DataLayout &DL, AssumptionCache AC)
	If we have a conditional branch on a PHI node value that is defined in the same block as the branch and if any PHI entries are constants, thread edges corresponding to that entry to be branches to their ultimate destination. More...

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

static bool	SimplifyCondBranchToTwoReturns (BranchInst *BI, IRBuilder<> &Builder)
	If we found a conditional branch that goes to two returning blocks, try to merge them together into one return, introducing a select if the return values disagree. More...

static bool	tryCSEWithPredecessor (Instruction Inst, BasicBlock PB)
	Return true if the given instruction is available in its predecessor block. More...

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. More...

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, const DataLayout &DL, const TargetTransformInfo &TTI)

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

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

static bool	SimplifyTerminatorOnSelect (Instruction OldTerm, Value Cond, BasicBlock TrueBB, BasicBlock FalseBB, uint32_t TrueWeight, uint32_t FalseWeight)

static bool	SimplifySwitchOnSelect (SwitchInst SI, SelectInst Select)

static bool	SimplifyIndirectBrOnSelect (IndirectBrInst IBI, SelectInst SI)

static bool	SimplifyBranchOnICmpChain (BranchInst *BI, IRBuilder<> &Builder, const DataLayout &DL)
	The specified branch is a conditional branch. More...

static bool	removeEmptyCleanup (CleanupReturnInst *RI)

static bool	mergeCleanupPad (CleanupReturnInst *RI)

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

static void	createUnreachableSwitchDefault (SwitchInst *Switch)

static bool	TurnSwitchRangeIntoICmp (SwitchInst *SI, IRBuilder<> &Builder)
	Turn a switch with two reachable destinations into an integer range comparison and branch. More...

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

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

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. More...

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. More...

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

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

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. More...

static uintptr_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, uintptr_t MaxCasesPerResult)

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

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

static bool	switchToSelect (SwitchInst *SI, IRBuilder<> &Builder, 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 only two different constant values, replace the switch with select. More...

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. More...

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. More...

static bool	SwitchToLookupTable (SwitchInst *SI, IRBuilder<> &Builder, 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. More...

static bool	isSwitchDense (ArrayRef< int64_t > Values)

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. More...

static bool	TryToMergeLandingPad (LandingPadInst LPad, BranchInst BI, BasicBlock *BB)
	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. More...

static BasicBlock *	allPredecessorsComeFromSameSource (BasicBlock *BB)

static bool	removeUndefIntroducingPredecessor (BasicBlock *BB)
	If BB has an incoming value that will always trigger undefined behavior (eg. More...

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 >	DupRet ("simplifycfg-dup-ret", cl::Hidden, cl::init(false), cl::desc("Duplicate return instructions into unconditional branches"))

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"))

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE "simplifycfg"

Definition at line 86 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 301 of file SimplifyCFG.cpp.

References llvm::BasicBlock::phis().

Referenced by FitWeights(), FoldCondBranchOnPHI(), HoistThenElseCodeToIf(), and SwitchToLookupTable().

◆ allPredecessorsComeFromSameSource()

static BasicBlock* allPredecessorsComeFromSameSource ( BasicBlock * BB )

static

Definition at line 5849 of file SimplifyCFG.cpp.

References E, llvm::FoldBranchToCommonDest(), FoldCondBranchOnPHI(), llvm::BranchInst::getCondition(), llvm::BasicBlock::getContext(), llvm::ConstantInt::getFalse(), llvm::Instruction::getNumSuccessors(), llvm::Instruction::getParent(), llvm::BasicBlock::getParent(), llvm::BasicBlock::getSinglePredecessor(), llvm::Instruction::getSuccessor(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::ConstantInt::getTrue(), llvm::Function::hasFnAttribute(), HoistThenElseCodeToIf(), I, llvm::BasicBlock::instructionsWithoutDebug(), llvm::BranchInst::isConditional(), llvm::isImpliedByDomCondition(), mergeConditionalStores(), MergeCondStores, P, llvm::pred_begin(), llvm::pred_end(), llvm::predecessors(), llvm::RecursivelyDeleteTriviallyDeadInstructions(), llvm::BranchInst::setCondition(), SimplifyBranchOnICmpChain(), SimplifyCondBranchToCondBranch(), and SpeculativelyExecuteBB().

◆ BlockIsSimpleEnoughToThreadThrough()

static bool BlockIsSimpleEnoughToThreadThrough ( BasicBlock * BB )

static

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

Definition at line 2150 of file SimplifyCFG.cpp.

References llvm::Instruction::getParent(), llvm::BasicBlock::instructionsWithoutDebug(), Size, and llvm::Value::users().

Referenced by FoldCondBranchOnPHI(), and SimplifyCondBranchToCondBranch().

◆ canSinkInstructions()

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

static

◆ CasesAreContiguous()

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

static

Definition at line 4313 of file SimplifyCFG.cpp.

References llvm::array_pod_sort(), assert(), llvm::SmallVectorTemplateCommon< T >::begin(), ConstantIntSortPredicate(), E, llvm::SmallVectorTemplateCommon< T >::end(), I, and llvm::SmallVectorBase::size().

Referenced by TurnSwitchRangeIntoICmp().

◆ ComputeSpeculationCost()

static unsigned 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 315 of file SimplifyCFG.cpp.

References assert(), llvm::TargetTransformInfo::getUserCost(), and llvm::isSafeToSpeculativelyExecute().

◆ 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 4644 of file SimplifyCFG.cpp.

References llvm::ConstantFoldCompareInstOperands(), llvm::ConstantFoldInstOperands(), llvm::ISD::ConstantPool, E, llvm::User::getNumOperands(), llvm::User::getOperand(), llvm::Constant::isAllOnesValue(), llvm::Constant::isNullValue(), LookupConstant(), N, llvm::SmallVectorTemplateBase< T >::push_back(), and llvm::MCID::Select.

Referenced by GetCaseResults().

◆ ConstantIntSortPredicate()

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

static

Definition at line 948 of file SimplifyCFG.cpp.

References llvm::ConstantInt::getValue(), and llvm::APInt::ult().

Referenced by CasesAreContiguous().

◆ ConvertTwoCaseSwitch()

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

static

Definition at line 4831 of file SimplifyCFG.cpp.

References assert(), llvm::IRBuilder< T, Inserter >::CreateICmpEQ(), llvm::IRBuilder< T, Inserter >::CreateSelect(), first, and second.

◆ createUnreachableSwitchDefault()

static void createUnreachableSwitchDefault ( SwitchInst * Switch )

static

Definition at line 4324 of file SimplifyCFG.cpp.

References llvm::dbgs(), EraseTerminatorAndDCECond(), llvm::BasicBlock::front(), llvm::Value::getContext(), llvm::SwitchInst::getDefaultDest(), llvm::Instruction::getParent(), llvm::BasicBlock::getTerminator(), LLVM_DEBUG, llvm::SwitchInst::setDefaultDest(), llvm::SplitBlock(), and llvm::SplitBlockPredecessors().

Referenced by TurnSwitchRangeIntoICmp().

◆ DominatesMergePoint()

static bool DominatesMergePoint	(	Value *	V,
		BasicBlock *	BB,
		SmallPtrSetImpl< Instruction *> &	AggressiveInsts,
		int &	BudgetRemaining,
		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 CostRemaining 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, CostRemaining is decreased by the cost of V plus its non-dominating operands. If that cost is greater than CostRemaining, false is returned and CostRemaining is undefined.

Definition at line 339 of file SimplifyCFG.cpp.

References C, llvm::ComputeSpeculationCost(), llvm::SmallPtrSetImpl< PtrType >::count(), llvm::Depth, llvm::dyn_cast(), llvm::SmallPtrSetImplBase::empty(), llvm::Instruction::getParent(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), I, llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::BranchInst::isConditional(), llvm::isSafeToSpeculativelyExecute(), MaxSpeculationDepth, llvm::User::op_begin(), llvm::User::op_end(), and SpeculateOneExpensiveInst.

Referenced by 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 748 of file SimplifyCFG.cpp.

References llvm::sys::fs::remove().

Referenced by setBranchWeights().

◆ eliminateDeadSwitchCases()

static bool eliminateDeadSwitchCases	(	SwitchInst *	SI,
		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 4456 of file SimplifyCFG.cpp.

◆ ensureValueAvailableInSuccessor()

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

static

Definition at line 2896 of file SimplifyCFG.cpp.

References llvm::PHINode::addIncoming(), assert(), llvm::BasicBlock::begin(), llvm::PHINode::Create(), llvm::BasicBlock::front(), llvm::UndefValue::get(), llvm::PHINode::getIncomingValueForBlock(), getParent(), llvm::BasicBlock::getSingleSuccessor(), llvm::Value::getType(), llvm::BasicBlock::hasNPredecessors(), I, llvm::pred_begin(), and llvm::predecessors().

Referenced by mergeConditionalStoreToAddress().

◆ EraseTerminatorAndDCECond()

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

static

Definition at line 681 of file SimplifyCFG.cpp.

Referenced by createUnreachableSwitchDefault(), FitWeights(), HoistThenElseCodeToIf(), setBranchWeights(), and SimplifyCondBranchToTwoReturns().

◆ 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 2550 of file SimplifyCFG.cpp.

References llvm::Instruction::extractProfMetadata().

◆ 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 4517 of file SimplifyCFG.cpp.

References assert(), llvm::MCID::Branch, llvm::dyn_cast(), llvm::BasicBlock::getFirstNonPHIOrDbg(), llvm::BasicBlock::getSinglePredecessor(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::BranchInst::isUnconditional(), and llvm::BasicBlock::phis().

Referenced by ForwardSwitchConditionToPHI().

◆ findUniqueStoreInBlocks()

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

static

Definition at line 2879 of file SimplifyCFG.cpp.

References SI.

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 990 of file SimplifyCFG.cpp.

◆ FoldCondBranchOnPHI()

static bool FoldCondBranchOnPHI	(	BranchInst *	BI,
		const DataLayout &	DL,
		AssumptionCache *	AC
	)

static

If we have a conditional branch on a PHI node value that is defined in the same block as the branch and if any PHI entries are constants, thread edges corresponding to that entry to be branches to their ultimate destination.

Definition at line 2175 of file SimplifyCFG.cpp.

References AddPredecessorToBlock(), llvm::any_of(), llvm::BasicBlock::begin(), BlockIsSimpleEnoughToThreadThrough(), llvm::CallBase::cannotDuplicate(), llvm::BasicBlock::Create(), llvm::BranchInst::Create(), llvm::Value::deleteValue(), llvm::dyn_cast(), llvm::DenseMapBase< DenseMap< KeyT, ValueT, KeyInfoT, BucketT >, KeyT, ValueT, KeyInfoT, BucketT >::end(), llvm::DenseMapBase< DenseMap< KeyT, ValueT, KeyInfoT, BucketT >, KeyT, ValueT, KeyInfoT, BucketT >::find(), llvm::FoldSingleEntryPHINodes(), llvm::BranchInst::getCondition(), llvm::BasicBlock::getContext(), llvm::Instruction::getDebugLoc(), llvm::PHINode::getIncomingBlock(), llvm::PHINode::getIncomingValue(), llvm::PHINode::getIncomingValueForBlock(), llvm::BasicBlock::getInstList(), llvm::Value::getName(), llvm::PHINode::getNumIncomingValues(), llvm::Instruction::getNumSuccessors(), llvm::Instruction::getParent(), llvm::BasicBlock::getParent(), llvm::Instruction::getSuccessor(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::ConstantInt::getType(), llvm::ConstantInt::getZExtValue(), llvm::Value::hasOneUse(), I, llvm::iplist_impl< IntrusiveListT, TraitsT >::insert(), llvm::CallBase::isConvergent(), llvm::Type::isIntegerTy(), llvm::Instruction::mayHaveSideEffects(), N, llvm::User::op_begin(), llvm::User::op_end(), llvm::AssumptionCache::registerAssumption(), llvm::BasicBlock::removePredecessor(), llvm::Value::setName(), llvm::Instruction::setSuccessor(), and llvm::SimplifyInstruction().

Referenced by allPredecessorsComeFromSameSource().

◆ FoldTwoEntryPHINode()

static bool FoldTwoEntryPHINode	(	PHINode *	PN,
		const TargetTransformInfo &	TTI,
		const DataLayout &	DL
	)

static

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

Definition at line 2294 of file SimplifyCFG.cpp.

References llvm::BasicBlock::begin(), llvm::SmallPtrSetImpl< PtrType >::count(), llvm::IRBuilder< T, Inserter >::CreateBr(), llvm::IRBuilder< T, Inserter >::CreateSelect(), llvm::dbgs(), DominatesMergePoint(), llvm::dyn_cast(), llvm::Instruction::eraseFromParent(), llvm::GetIfCondition(), llvm::PHINode::getIncomingBlock(), llvm::PHINode::getIncomingValue(), llvm::Value::getName(), llvm::Instruction::getParent(), llvm::BasicBlock::getParent(), llvm::BasicBlock::getTerminator(), llvm::Value::getType(), llvm::Function::hasFnAttribute(), llvm::hoistAllInstructionsInto(), I, llvm::Type::isIntegerTy(), llvm::Instruction::isTerminator(), LLVM_DEBUG, llvm::PatternMatch::m_AnyIntegralConstant(), llvm::PatternMatch::m_CombineOr(), llvm::PatternMatch::m_Not(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::pred_begin(), llvm::Value::replaceAllUsesWith(), llvm::IRBuilderBase::SetInsertPoint(), llvm::SimplifyInstruction(), std::swap(), llvm::Value::takeName(), llvm::TargetTransformInfo::TCC_Basic, and TwoEntryPHINodeFoldingThreshold.

Referenced by removeUndefIntroducingPredecessor().

◆ 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 4548 of file SimplifyCFG.cpp.

References llvm::SwitchInst::cases(), llvm::count(), FindPHIForConditionForwarding(), llvm::SwitchInst::getCondition(), llvm::Instruction::getParent(), llvm::BasicBlock::phis(), llvm::PHINode::setIncomingValue(), and llvm::SmallVectorBase::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 969 of file SimplifyCFG.cpp.

References assert(), llvm::SmallVectorTemplateCommon< T, typename >::back(), llvm::SmallVectorTemplateCommon< T, typename >::front(), llvm::Instruction::getMetadata(), llvm::MDNode::getNumOperands(), llvm::MDNode::getOperand(), llvm::ConstantInt::getValue(), llvm::APInt::getZExtValue(), llvm::CmpInst::ICMP_EQ, llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::SmallVectorBase::size(), and std::swap().

Referenced by FitWeights(), SimplifySwitchOnSelect(), and TurnSwitchRangeIntoICmp().

◆ 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 4678 of file SimplifyCFG.cpp.

References C, ConstantFold(), llvm::ISD::ConstantPool, llvm::SwitchInst::getCondition(), llvm::Instruction::getNumSuccessors(), llvm::Instruction::getParent(), llvm::Instruction::getSuccessor(), llvm::Use::getUser(), llvm::DenseMapBase< SmallDenseMap< KeyT, ValueT, InlineBuckets, KeyInfoT, BucketT >, KeyT, ValueT, KeyInfoT, BucketT >::insert(), llvm::BasicBlock::instructionsWithoutDebug(), llvm::Instruction::isExceptionalTerminator(), llvm::Instruction::isTerminator(), LookupConstant(), llvm::Value::uses(), 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 409 of file SimplifyCFG.cpp.

References llvm::dyn_cast(), llvm::ConstantInt::get(), llvm::ConstantExpr::getIntegerCast(), llvm::DataLayout::getIntPtrType(), llvm::ConstantInt::getType(), llvm::Value::getType(), and llvm::Type::isPointerTy().

◆ HasBranchWeights()

static bool HasBranchWeights ( const Instruction * I )

inlinestatic

Definition at line 957 of file SimplifyCFG.cpp.

References llvm::Instruction::getMetadata(), and llvm::MDNode::getOperand().

Referenced by FitWeights(), SimplifySwitchOnSelect(), and TurnSwitchRangeIntoICmp().

◆ HoistThenElseCodeToIf()

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

static

Given a conditional branch that goes to BB1 and BB2, hoist any common code in the two blocks up into the branch block.

The caller of this function guarantees that BI's block dominates BB1 and BB2.

Definition at line 1238 of file SimplifyCFG.cpp.

References AddPredecessorToBlock(), llvm::Instruction::andIRFlags(), llvm::Instruction::applyMergedLocation(), assert(), llvm::BasicBlock::begin(), llvm::Instruction::clone(), llvm::combineMetadata(), llvm::IRBuilder< T, Inserter >::CreateSelect(), llvm::dyn_cast(), EraseTerminatorAndDCECond(), llvm::BranchInst::getCondition(), llvm::Instruction::getDebugLoc(), llvm::BasicBlock::getInstList(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::Value::getName(), llvm::Instruction::getParent(), llvm::BranchInst::getSuccessor(), llvm::Value::getType(), llvm::iplist_impl< IntrusiveListT, TraitsT >::insert(), llvm::Instruction::isIdenticalToWhenDefined(), llvm::TargetTransformInfo::isProfitableToHoist(), isSafeToHoistInvoke(), llvm::isSafeToSpeculativelyExecute(), llvm::Instruction::isTerminator(), llvm::Type::isVoidTy(), passingValueIsAlwaysUndefined(), llvm::Value::replaceAllUsesWith(), SI, llvm::iplist_impl< IntrusiveListT, TraitsT >::splice(), llvm::successors(), and llvm::Value::takeName().

Referenced by allPredecessorsComeFromSameSource().

◆ InitializeUniqueCases()

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

static

Definition at line 4768 of file SimplifyCFG.cpp.

References llvm::SwitchInst::cases(), first, GetCaseResults(), llvm::SwitchInst::getDefaultDest(), llvm::BasicBlock::getFirstNonPHIOrDbg(), MapCaseToResult(), and Results.

◆ isLifeTimeMarker()

static bool isLifeTimeMarker ( const Instruction * I )

static

Definition at line 1428 of file SimplifyCFG.cpp.

Referenced by canSinkInstructions().

◆ isProfitableToFoldUnconditional()

static bool isProfitableToFoldUnconditional	(	BranchInst *	SI1,
		BranchInst *	SI2,
		Instruction *	Cond,
		SmallVectorImpl< PHINode *> &	PhiNodes
	)

static

Return true if it is safe and profitable to merge these two terminator instructions together, where SI1 is an unconditional branch.

PhiNodes will store all PHI nodes in common successors.

Definition at line 261 of file SimplifyCFG.cpp.

◆ isSafeToHoistInvoke()

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

static

Definition at line 1219 of file SimplifyCFG.cpp.

References I, passingValueIsAlwaysUndefined(), and llvm::successors().

Referenced by HoistThenElseCodeToIf().

◆ 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 1885 of file SimplifyCFG.cpp.

References llvm::dyn_cast(), llvm::StoreInst::getPointerOperand(), I, llvm::BasicBlock::instructionsWithoutDebug(), llvm::StoreInst::isSimple(), llvm::reverse(), and SI.

Referenced by SpeculativelyExecuteBB().

◆ isSwitchDense()

static bool isSwitchDense ( ArrayRef< int64_t > Values )

static

Definition at line 5531 of file SimplifyCFG.cpp.

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

Referenced by ReduceSwitchRange().

◆ 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 4632 of file SimplifyCFG.cpp.

References C, and llvm::DenseMapBase< SmallDenseMap< KeyT, ValueT, InlineBuckets, KeyInfoT, BucketT >, KeyT, ValueT, KeyInfoT, BucketT >::lookup().

Referenced by ConstantFold(), and GetCaseResults().

◆ MapCaseToResult()

static uintptr_t MapCaseToResult	(	ConstantInt *	CaseVal,
		SwitchCaseResultVectorTy &	UniqueResults,
		Constant *	Result
	)

static

Definition at line 4749 of file SimplifyCFG.cpp.

Referenced by InitializeUniqueCases().

◆ mergeCleanupPad()

static bool mergeCleanupPad ( CleanupReturnInst * RI )

static

Definition at line 4060 of file SimplifyCFG.cpp.

References assert(), llvm::BasicBlock::begin(), llvm::classifyEHPersonality(), llvm::CoreCLR, llvm::BranchInst::Create(), llvm::dbgs(), DupRet, llvm::dyn_cast(), E, llvm::SmallVectorBase::empty(), llvm::Instruction::eraseFromParent(), llvm::BasicBlock::eraseFromParent(), llvm::FoldReturnIntoUncondBranch(), llvm::BasicBlock::front(), llvm::UndefValue::get(), llvm::CleanupReturnInst::getCleanupPad(), llvm::Value::getContext(), llvm::BasicBlock::getFirstNonPHIOrDbg(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::BasicBlock::getParent(), llvm::Function::getPersonalityFn(), llvm::BasicBlock::getSinglePredecessor(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::CleanupReturnInst::getUnwindDest(), llvm::Instruction::isTerminator(), LLVM_DEBUG, P, llvm::SmallVectorImpl< T >::pop_back_val(), llvm::pred_begin(), llvm::pred_empty(), llvm::pred_end(), llvm::SmallVectorTemplateBase< T >::push_back(), removeEmptyCleanup(), llvm::Value::replaceAllUsesWith(), SI, SimplifyCondBranchToTwoReturns(), and llvm::SmallVectorBase::size().

◆ mergeConditionalStores()

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

static

Definition at line 3107 of file SimplifyCFG.cpp.

References llvm::Address, llvm::Instruction::getParent(), llvm::BasicBlock::getSinglePredecessor(), llvm::BasicBlock::getSingleSuccessor(), llvm::BranchInst::getSuccessor(), llvm::Value::hasNUses(), llvm::SmallPtrSetImpl< PtrType >::insert(), mergeConditionalStoreToAddress(), P, llvm::set_intersect(), SI, and std::swap().

Referenced by allPredecessorsComeFromSameSource(), and SimplifyCondBranchToCondBranch().

◆ mergeConditionalStoreToAddress()

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

static

Definition at line 2945 of file SimplifyCFG.cpp.

References assert(), E, llvm::BasicBlock::end(), ensureValueAvailableInSuccessor(), llvm::Instruction::eraseFromParent(), llvm::find(), findUniqueStoreInBlocks(), llvm::Instruction::getAAMetadata(), llvm::DataLayout::getABITypeAlignment(), llvm::StoreInst::getAlignment(), llvm::BasicBlock::getFirstInsertionPt(), llvm::Instruction::getParent(), llvm::BasicBlock::getSinglePredecessor(), llvm::BasicBlock::getTerminator(), llvm::Value::getType(), llvm::TargetTransformInfo::getUserCost(), llvm::StoreInst::getValueOperand(), I, llvm::BasicBlock::instructionsWithoutDebug(), llvm::Instruction::isTerminator(), llvm::StoreInst::isUnordered(), llvm::Instruction::mayReadOrWriteMemory(), MergeCondStoresAggressively, PHINodeFoldingThreshold, llvm::pred_begin(), llvm::pred_end(), llvm::Instruction::setAAMetadata(), llvm::StoreInst::setAlignment(), SI, llvm::SplitBlockAndInsertIfThen(), llvm::SplitBlockPredecessors(), and llvm::TargetTransformInfo::TCC_Basic.

Referenced by mergeConditionalStores().

◆ passingValueIsAlwaysUndefined()

static bool passingValueIsAlwaysUndefined	(	Value *	V,
		Instruction *	I
	)

static

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

Definition at line 5964 of file SimplifyCFG.cpp.

References C, llvm::dyn_cast(), llvm::BasicBlock::end(), GEP, llvm::Instruction::getFunction(), llvm::Instruction::getParent(), I, llvm::Constant::isNullValue(), llvm::NullPointerIsDefined(), llvm::Value::use_empty(), and llvm::Value::user_begin().

Referenced by HoistThenElseCodeToIf(), isSafeToHoistInvoke(), removeUndefIntroducingPredecessor(), and SpeculativelyExecuteBB().

◆ 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 5550 of file SimplifyCFG.cpp.

References assert(), C, llvm::SwitchInst::cases(), llvm::countTrailingZeros(), llvm::IRBuilder< T, Inserter >::CreateLShr(), llvm::IRBuilder< T, Inserter >::CreateOr(), llvm::IRBuilder< T, Inserter >::CreateShl(), llvm::IRBuilder< T, Inserter >::CreateSub(), llvm::DataLayout::fitsInLegalInteger(), llvm::ConstantInt::get(), llvm::SwitchInst::getCondition(), llvm::SwitchInst::getNumCases(), llvm::Instruction::getParent(), llvm::BasicBlock::getSinglePredecessor(), llvm::Value::getType(), isSwitchDense(), llvm::SmallVectorTemplateBase< T >::push_back(), llvm::User::replaceUsesOfWith(), llvm::IRBuilderBase::SetInsertPoint(), SI, and llvm::sort().

◆ removeEmptyCleanup()

static bool removeEmptyCleanup ( CleanupReturnInst * RI )

static

Definition at line 3923 of file SimplifyCFG.cpp.

References llvm::PHINode::addIncoming(), assert(), llvm::BasicBlock::begin(), llvm::dyn_cast(), E, llvm::BasicBlock::eraseFromParent(), llvm::PHINode::getBasicBlockIndex(), llvm::CleanupReturnInst::getCleanupPad(), llvm::BasicBlock::getFirstNonPHI(), llvm::PHINode::getIncomingBlock(), llvm::PHINode::getIncomingValue(), llvm::IntrinsicInst::getIntrinsicID(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::PHINode::getNumIncomingValues(), llvm::Instruction::getParent(), llvm::BasicBlock::getTerminator(), llvm::CleanupReturnInst::getUnwindDest(), llvm::Value::hasOneUse(), I, llvm::ARM_PROC::IE, llvm::Instruction::moveBefore(), pred, llvm::pred_begin(), llvm::pred_end(), llvm::predecessors(), llvm::PHINode::removeIncomingValue(), llvm::removeUnwindEdge(), llvm::User::replaceUsesOfWith(), and llvm::Value::use_empty().

Referenced by mergeCleanupPad().

◆ RemoveSwitchAfterSelectConversion()

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

static

Definition at line 4862 of file SimplifyCFG.cpp.

References llvm::PHINode::addIncoming(), llvm::IRBuilder< T, Inserter >::CreateBr(), llvm::Instruction::eraseFromParent(), llvm::PHINode::getBasicBlockIndex(), llvm::SwitchInst::getNumSuccessors(), llvm::Instruction::getParent(), llvm::SwitchInst::getSuccessor(), llvm::PHINode::removeIncomingValue(), and llvm::BasicBlock::removePredecessor().

◆ removeUndefIntroducingPredecessor()

static bool removeUndefIntroducingPredecessor ( BasicBlock * BB )

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 6017 of file SimplifyCFG.cpp.

References assert(), llvm::BasicBlock::begin(), llvm::ConstantFoldTerminator(), llvm::IRBuilder< T, Inserter >::CreateBr(), llvm::IRBuilder< T, Inserter >::CreateUnreachable(), llvm::dbgs(), llvm::DeleteDeadBlock(), llvm::EliminateDuplicatePHINodes(), llvm::Instruction::eraseFromParent(), FoldTwoEntryPHINode(), llvm::Function::getEntryBlock(), llvm::BasicBlock::getParent(), llvm::BasicBlock::getSinglePredecessor(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::BranchInst::isUnconditional(), LLVM_DEBUG, llvm::MergeBlockIntoPredecessor(), passingValueIsAlwaysUndefined(), llvm::BasicBlock::phis(), llvm::pred_empty(), llvm::BasicBlock::removePredecessor(), llvm::IRBuilderBase::SetInsertPoint(), SinkCommon, and SinkCommonCodeFromPredecessors().

◆ 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 5225 of file SimplifyCFG.cpp.

References assert(), llvm::dyn_cast(), E, llvm::ConstantInt::get(), llvm::BranchInst::getCondition(), llvm::ConstantInt::getFalse(), llvm::ConstantExpr::getICmp(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::CmpInst::getPredicate(), llvm::ConstantInt::getTrue(), llvm::Value::getType(), llvm::BasicBlock::getUniquePredecessor(), llvm::pred_begin(), llvm::pred_end(), 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 229 of file SimplifyCFG.cpp.

References llvm::SmallPtrSetImpl< PtrType >::count(), Fail, llvm::PHINode::getIncomingValueForBlock(), llvm::Instruction::getParent(), llvm::succ_begin(), llvm::succ_end(), and llvm::successors().

Referenced by FitWeights().

◆ setBranchWeights() [1/2]

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

static

Definition at line 789 of file SimplifyCFG.cpp.

References llvm::any_of(), llvm::BasicBlock::getContext(), llvm::Instruction::getParent(), N, llvm::Instruction::setMetadata(), and llvm::RISCVFenceField::W.

Referenced by FitWeights(), sumEdgeCount(), and TurnSwitchRangeIntoICmp().

◆ setBranchWeights() [2/2]

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

static

◆ 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 5165 of file SimplifyCFG.cpp.

References llvm::SwitchInst::getNumCases(), llvm::TargetTransformInfo::isTypeLegal(), and UINT64_MAX.

Referenced by SwitchToLookupTable().

◆ SimplifyBranchOnICmpChain()

static bool SimplifyBranchOnICmpChain	(	BranchInst *	BI,
		IRBuilder<> &	Builder,
		const DataLayout &	DL
	)

static

The specified branch is a conditional branch.

Check to see if it is branching on an or/and chain of icmp instructions, and fold it into a switch instruction if so.

Definition at line 3692 of file SimplifyCFG.cpp.

Referenced by allPredecessorsComeFromSameSource().

◆ SimplifyCondBranchToCondBranch()

static bool SimplifyCondBranchToCondBranch	(	BranchInst *	PBI,
		BranchInst *	BI,
		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 3219 of file SimplifyCFG.cpp.

References llvm::PHINode::addIncoming(), assert(), llvm::BasicBlock::begin(), BlockIsSimpleEnoughToThreadThrough(), llvm::BasicBlock::Create(), llvm::PHINode::Create(), llvm::BranchInst::Create(), llvm::IRBuilder< T, Inserter >::CreateNot(), llvm::dbgs(), llvm::StringRef::front(), llvm::ConstantInt::get(), llvm::PHINode::getBasicBlockIndex(), llvm::BranchInst::getCondition(), llvm::PHINode::getIncomingValue(), llvm::PHINode::getIncomingValueForBlock(), llvm::Type::getInt1Ty(), llvm::Value::getName(), llvm::Instruction::getParent(), llvm::BasicBlock::getParent(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::BranchInst::isConditional(), LLVM_DEBUG, mergeConditionalStores(), MergeCondStores, P, llvm::pred_begin(), llvm::pred_end(), and llvm::BranchInst::setCondition().

Referenced by allPredecessorsComeFromSameSource().

◆ SimplifyCondBranchToTwoReturns()

static bool SimplifyCondBranchToTwoReturns	(	BranchInst *	BI,
		IRBuilder<> &	Builder
	)

static

If we found a conditional branch that goes to two returning blocks, try to merge them together into one return, introducing a select if the return values disagree.

Definition at line 2445 of file SimplifyCFG.cpp.

References assert(), llvm::IRBuilder< T, Inserter >::CreateRet(), llvm::IRBuilder< T, Inserter >::CreateRetVoid(), llvm::IRBuilder< T, Inserter >::CreateSelect(), llvm::dbgs(), EraseTerminatorAndDCECond(), llvm::BranchInst::getCondition(), llvm::BasicBlock::getFirstNonPHIOrDbg(), llvm::Instruction::getParent(), llvm::ReturnInst::getReturnValue(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::BranchInst::isConditional(), llvm::Instruction::isTerminator(), LLVM_DEBUG, llvm::BasicBlock::removePredecessor(), and llvm::IRBuilderBase::SetInsertPoint().

Referenced by mergeCleanupPad().

◆ SimplifyIndirectBrOnSelect()

static bool SimplifyIndirectBrOnSelect	(	IndirectBrInst *	IBI,
		SelectInst *	SI
	)

static

Definition at line 3557 of file SimplifyCFG.cpp.

References llvm::SwitchInstProfUpdateWrapper::addCase(), llvm::PHINode::addIncoming(), assert(), llvm::BasicBlock::begin(), llvm::SwitchInst::case_default(), llvm::BasicBlock::Create(), llvm::IRBuilder< T, Inserter >::CreateBr(), llvm::dyn_cast(), llvm::Instruction::eraseFromParent(), llvm::SwitchInst::findCaseDest(), llvm::SwitchInst::findCaseValue(), llvm::BasicBlock::front(), llvm::BlockAddress::getBasicBlock(), llvm::SelectInst::getCondition(), llvm::SwitchInst::getCondition(), llvm::BasicBlock::getContext(), llvm::Instruction::getDebugLoc(), llvm::SwitchInst::getDefaultDest(), llvm::ConstantInt::getFalse(), llvm::SelectInst::getFalseValue(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::BasicBlock::getParent(), llvm::CmpInst::getPredicate(), llvm::BasicBlock::getSinglePredecessor(), llvm::Instruction::getSuccessor(), llvm::SwitchInstProfUpdateWrapper::getSuccessorWeight(), llvm::BasicBlock::getTerminator(), llvm::ConstantInt::getTrue(), llvm::SelectInst::getTrueValue(), llvm::Value::hasOneUse(), llvm::CmpInst::ICMP_EQ, llvm::Value::replaceAllUsesWith(), llvm::IRBuilderBase::SetCurrentDebugLocation(), llvm::IRBuilderBase::SetInsertPoint(), llvm::User::setOperand(), llvm::SwitchInstProfUpdateWrapper::setSuccessorWeight(), SI, llvm::SimplifyInstruction(), SimplifyTerminatorOnSelect(), std::swap(), and llvm::Instruction::user_back().

◆ SimplifySwitchOnSelect()

static bool SimplifySwitchOnSelect	(	SwitchInst *	SI,
		SelectInst *	Select
	)

static

Definition at line 3521 of file SimplifyCFG.cpp.

References llvm::dyn_cast(), llvm::SwitchInst::findCaseValue(), GetBranchWeights(), llvm::SelectInst::getCondition(), llvm::SelectInst::getFalseValue(), llvm::SwitchInst::getNumCases(), llvm::SelectInst::getTrueValue(), HasBranchWeights(), SimplifyTerminatorOnSelect(), and llvm::SmallVectorBase::size().

◆ SimplifyTerminatorOnSelect()

static bool SimplifyTerminatorOnSelect	(	Instruction *	OldTerm,
		Value *	Cond,
		BasicBlock *	TrueBB,
		BasicBlock *	FalseBB,
		uint32_t	TrueWeight,
		uint32_t	FalseWeight
	)

static

Definition at line 3458 of file SimplifyCFG.cpp.

Referenced by SimplifyIndirectBrOnSelect(), and SimplifySwitchOnSelect().

◆ SinkCommonCodeFromPredecessors()

static bool SinkCommonCodeFromPredecessors ( BasicBlock * BB )

static

Check whether BB's predecessors end with unconditional branches.

If it is true, sink any common code from the predecessors to BB. We also allow one predecessor to end with conditional branch (but no more than one).

Definition at line 1705 of file SimplifyCFG.cpp.

Referenced by removeUndefIntroducingPredecessor().

◆ sinkLastInstruction()

static bool sinkLastInstruction ( ArrayRef< BasicBlock *> Blocks )

static

Definition at line 1545 of file SimplifyCFG.cpp.

References llvm::PHINode::addIncoming(), llvm::all_of(), llvm::Instruction::andIRFlags(), llvm::any_of(), llvm::Instruction::applyMergedLocation(), assert(), llvm::SmallVectorImpl< T >::clear(), llvm::combineMetadataForCSE(), llvm::PHINode::Create(), llvm::dyn_cast(), E, llvm::Instruction::eraseFromParent(), Fail, llvm::SmallVectorTemplateCommon< T >::front(), llvm::Instruction::getDebugLoc(), llvm::User::getNumOperands(), llvm::User::getOperand(), llvm::User::getOperandUse(), llvm::Instruction::getParent(), llvm::ilist_node_with_parent< NodeTy, ParentTy, Options >::getPrevNode(), llvm::Instruction::moveBefore(), llvm::RISCVFenceField::O, llvm::operator*(), llvm::SmallVectorTemplateBase< T >::push_back(), llvm::Use::set(), llvm::SmallVectorBase::size(), llvm::Value::user_begin(), and llvm::Value::user_empty().

Referenced by llvm::GVNExpression::Expression::dump().

◆ SpeculativelyExecuteBB()

static bool SpeculativelyExecuteBB	(	BranchInst *	BI,
		BasicBlock *	ThenBB,
		const TargetTransformInfo &	TTI
	)

static

Speculate a conditional basic block flattening the CFG.

Note that this is a very risky transform currently. Speculating instructions like this is most often not desirable. Instead, there is an MI pass which can do it with full awareness of the resource constraints. However, some cases are "obvious" and we should do directly. An example of this is speculating a single, reasonably cheap instruction.

There is only one distinct advantage to flattening the CFG at the IR level: it makes very common but simplistic optimizations such as are common in instcombine and the DAG combiner more powerful by removing CFG edges and modeling their effects with easier to reason about SSA value graphs.

An illustration of this transform is turning this IR:

BB:
  %cmp = icmp ult %x, %y
  br i1 %cmp, label %EndBB, label %ThenBB
ThenBB:
  %sub = sub %x, %y
  br label BB2
EndBB:
  %phi = phi [ %sub, %ThenBB ], [ 0, %EndBB ]
  ...

Into this IR:

BB:
  %cmp = icmp ult %x, %y
  %sub = sub %x, %y
  %cond = select i1 %cmp, 0, %sub
  ...

Returns: true if the conditional block is removed.

Definition at line 1957 of file SimplifyCFG.cpp.

References llvm::Instruction::applyMergedLocation(), assert(), llvm::BasicBlock::begin(), llvm::ComputeSpeculationCost(), llvm::IRBuilder< T, Inserter >::CreateSelect(), llvm::dbgs(), llvm::Instruction::dropUnknownNonDebugMetadata(), llvm::dyn_cast(), E, llvm::BasicBlock::end(), llvm::Instruction::eraseFromParent(), llvm::BranchInst::getCondition(), llvm::Instruction::getDebugLoc(), llvm::BasicBlock::getInstList(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::Instruction::getParent(), llvm::Instruction::getSuccessor(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::StoreInst::getValueOperand(), llvm::Value::hasNUses(), HoistCondStores, I, isSafeToSpeculateStore(), llvm::isSafeToSpeculativelyExecute(), LLVM_DEBUG, llvm::Instruction::mayHaveSideEffects(), llvm::User::op_begin(), llvm::User::op_end(), passingValueIsAlwaysUndefined(), PHINodeFoldingThreshold, llvm::BasicBlock::phis(), llvm::SmallVectorTemplateBase< T >::push_back(), llvm::User::setOperand(), llvm::iplist_impl< IntrusiveListT, TraitsT >::splice(), std::swap(), and llvm::TargetTransformInfo::TCC_Basic.

Referenced by allPredecessorsComeFromSameSource().

◆ STATISTIC() [1/7]

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

◆ STATISTIC() [2/7]

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

◆ STATISTIC() [3/7]

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

◆ STATISTIC() [4/7]

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

◆ STATISTIC() [5/7]

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

◆ STATISTIC() [6/7]

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

◆ STATISTIC() [7/7]

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

◆ SwitchToLookupTable()

static bool SwitchToLookupTable	(	SwitchInst *	SI,
		IRBuilder<> &	Builder,
		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 5291 of file SimplifyCFG.cpp.

◆ switchToSelect()

static bool switchToSelect	(	SwitchInst *	SI,
		IRBuilder<> &	Builder,
		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 only two different constant values, replace the switch with select.

Definition at line 4886 of file SimplifyCFG.cpp.

◆ tryCSEWithPredecessor()

static bool tryCSEWithPredecessor	(	Instruction *	Inst,
		BasicBlock *	PB
	)

static

Return true if the given instruction is available in its predecessor block.

If yes, the instruction will be removed.

Definition at line 2532 of file SimplifyCFG.cpp.

References llvm::Instruction::eraseFromParent(), I, llvm::Instruction::isIdenticalTo(), and llvm::Value::replaceAllUsesWith().

◆ TryToMergeLandingPad()

static bool TryToMergeLandingPad	(	LandingPadInst *	LPad,
		BranchInst *	BI,
		BasicBlock *	BB
	)

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 5743 of file SimplifyCFG.cpp.

References assert(), llvm::IRBuilder< T, Inserter >::CreateUnreachable(), llvm::dyn_cast(), E, llvm::Instruction::eraseFromParent(), llvm::FoldBranchToCommonDest(), llvm::Function::getEntryBlock(), llvm::BasicBlock::getFirstNonPHIOrDbg(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::InvokeInst::getNormalDest(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::BasicBlock::getParent(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::BasicBlock::getUniqueSuccessor(), llvm::InvokeInst::getUnwindDest(), llvm::BasicBlock::hasNPredecessorsOrMore(), I, llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::ICmpInst::isEquality(), llvm::Instruction::isIdenticalTo(), llvm::pred_begin(), llvm::pred_end(), llvm::predecessors(), llvm::InvokeInst::setUnwindDest(), llvm::succ_begin(), llvm::succ_end(), and llvm::TryToSimplifyUncondBranchFromEmptyBlock().

◆ TurnSwitchRangeIntoICmp()

static bool TurnSwitchRangeIntoICmp	(	SwitchInst *	SI,
		IRBuilder<> &	Builder
	)

static

Turn a switch with two reachable destinations into an integer range comparison and branch.

Definition at line 4337 of file SimplifyCFG.cpp.

References assert(), llvm::BasicBlock::begin(), llvm::SwitchInst::cases(), CasesAreContiguous(), llvm::IRBuilder< T, Inserter >::CreateAdd(), llvm::IRBuilder< T, Inserter >::CreateCondBr(), llvm::IRBuilder< T, Inserter >::CreateICmpULT(), createUnreachableSwitchDefault(), E, llvm::SmallVectorBase::empty(), llvm::Instruction::eraseFromParent(), llvm::ConstantInt::get(), GetBranchWeights(), llvm::SwitchInst::getCondition(), llvm::Value::getContext(), llvm::SwitchInst::getDefaultDest(), llvm::BasicBlock::getFirstNonPHIOrDbg(), llvm::Value::getName(), llvm::ConstantExpr::getNeg(), llvm::SwitchInst::getNumCases(), llvm::Instruction::getParent(), llvm::SwitchInst::getSuccessor(), llvm::ConstantInt::getTrue(), llvm::Value::getType(), HasBranchWeights(), I, llvm::Constant::isNullValue(), llvm::SmallVectorTemplateBase< T >::push_back(), setBranchWeights(), and llvm::SmallVectorBase::size().

◆ 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 4605 of file SimplifyCFG.cpp.

References C, llvm::Constant::isDLLImportDependent(), llvm::Constant::isThreadDependent(), and llvm::TargetTransformInfo::shouldBuildLookupTablesForConstant().

Referenced by GetCaseResults().

◆ 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 754 of file SimplifyCFG.cpp.

References llvm::array_pod_sort(), std::swap(), llvm::NVPTX::PTXLdStInstCode::V2, and llvm::Value::Value().

Referenced by setBranchWeights().

Variable Documentation

◆ DupRet

cl::opt<bool> DupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false), cl::desc("Duplicate return instructions into unconditional branches"))

static

Referenced by mergeCleanupPad().

◆ HoistCondStores

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

static

Referenced by SpeculativelyExecuteBB().

◆ 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"))

static

Referenced by DominatesMergePoint().

◆ 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"))

static

Referenced by allPredecessorsComeFromSameSource(), and 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"))

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)"))

static

Referenced by mergeConditionalStoreToAddress(), and SpeculativelyExecuteBB().

◆ SinkCommon

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

static

Referenced by removeUndefIntroducingPredecessor(), and llvm::SimplifyCFGPass::run().

◆ 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"))

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)"))

static

Referenced by FoldTwoEntryPHINode().

Macros

Functions

Variables

Macro Definition Documentation

◆ DEBUG_TYPE

Function Documentation

◆ AddPredecessorToBlock()

◆ allPredecessorsComeFromSameSource()

◆ BlockIsSimpleEnoughToThreadThrough()

◆ canSinkInstructions()

◆ CasesAreContiguous()

◆ ComputeSpeculationCost()

◆ ConstantFold()

◆ ConstantIntSortPredicate()

◆ ConvertTwoCaseSwitch()

◆ createUnreachableSwitchDefault()

◆ DominatesMergePoint()

◆ EliminateBlockCases()

◆ eliminateDeadSwitchCases()

◆ ensureValueAvailableInSuccessor()

◆ EraseTerminatorAndDCECond()

◆ extractPredSuccWeights()

◆ FindPHIForConditionForwarding()

◆ findUniqueStoreInBlocks()

◆ FitWeights()

◆ FoldCondBranchOnPHI()

◆ FoldTwoEntryPHINode()

◆ ForwardSwitchConditionToPHI()

◆ GetBranchWeights()

◆ GetCaseResults()

◆ GetConstantInt()

◆ HasBranchWeights()

◆ HoistThenElseCodeToIf()

◆ InitializeUniqueCases()

◆ isLifeTimeMarker()

◆ isProfitableToFoldUnconditional()

◆ isSafeToHoistInvoke()

◆ isSafeToSpeculateStore()

◆ isSwitchDense()

◆ LookupConstant()

◆ MapCaseToResult()

◆ mergeCleanupPad()

◆ mergeConditionalStores()

◆ mergeConditionalStoreToAddress()

◆ passingValueIsAlwaysUndefined()

◆ ReduceSwitchRange()

◆ removeEmptyCleanup()

◆ RemoveSwitchAfterSelectConversion()

◆ removeUndefIntroducingPredecessor()

◆ reuseTableCompare()

◆ SafeToMergeTerminators()

◆ setBranchWeights() [1/2]

◆ setBranchWeights() [2/2]

◆ ShouldBuildLookupTable()

◆ SimplifyBranchOnICmpChain()

◆ SimplifyCondBranchToCondBranch()

◆ SimplifyCondBranchToTwoReturns()

◆ SimplifyIndirectBrOnSelect()

◆ SimplifySwitchOnSelect()

◆ SimplifyTerminatorOnSelect()

◆ SinkCommonCodeFromPredecessors()

◆ sinkLastInstruction()

◆ SpeculativelyExecuteBB()

◆ STATISTIC() [1/7]

◆ STATISTIC() [2/7]

◆ STATISTIC() [3/7]

◆ STATISTIC() [4/7]

◆ STATISTIC() [5/7]

◆ STATISTIC() [6/7]

◆ STATISTIC() [7/7]

◆ SwitchToLookupTable()

◆ switchToSelect()

◆ tryCSEWithPredecessor()

◆ TryToMergeLandingPad()

◆ TurnSwitchRangeIntoICmp()

◆ ValidLookupTableConstant()

◆ ValuesOverlap()

Variable Documentation

◆ DupRet

◆ HoistCondStores