#include "InstCombineInternal.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/KnownBits.h"

Include dependency graph for InstCombineCompares.cpp:

Macros
#define	DEBUG_TYPE "instcombine"

Functions
	STATISTIC (NumSel, "Number of select opts")

static bool	addWithOverflow (APInt &Result, const APInt &In1, const APInt &In2, bool IsSigned=false)
	Compute Result = In1+In2, returning true if the result overflowed for this type. More...

static bool	subWithOverflow (APInt &Result, const APInt &In1, const APInt &In2, bool IsSigned=false)
	Compute Result = In1-In2, returning true if the result overflowed for this type. More...

static bool	hasBranchUse (ICmpInst &I)
	Given an icmp instruction, return true if any use of this comparison is a branch on sign bit comparison. More...

static bool	isSignBitCheck (ICmpInst::Predicate Pred, const APInt &RHS, bool &TrueIfSigned)
	Given an exploded icmp instruction, return true if the comparison only checks the sign bit. More...

static bool	isSignTest (ICmpInst::Predicate &Pred, const APInt &C)
	Returns true if the exploded icmp can be expressed as a signed comparison to zero and updates the predicate accordingly. More...

static void	computeSignedMinMaxValuesFromKnownBits (const KnownBits &Known, APInt &Min, APInt &Max)
	Given a signed integer type and a set of known zero and one bits, compute the maximum and minimum values that could have the specified known zero and known one bits, returning them in Min/Max. More...

static void	computeUnsignedMinMaxValuesFromKnownBits (const KnownBits &Known, APInt &Min, APInt &Max)
	Given an unsigned integer type and a set of known zero and one bits, compute the maximum and minimum values that could have the specified known zero and known one bits, returning them in Min/Max. More...

static Value *	evaluateGEPOffsetExpression (User *GEP, InstCombiner &IC, const DataLayout &DL)
	Return a value that can be used to compare the offset implied by a GEP to zero. More...

static bool	canRewriteGEPAsOffset (Value Start, Value Base, const DataLayout &DL, SetVector< Value *> &Explored)
	Returns true if we can rewrite Start as a GEP with pointer Base and some integer offset. More...

static void	setInsertionPoint (IRBuilder<> &Builder, Value *V, bool Before=true)

static Value *	rewriteGEPAsOffset (Value Start, Value Base, const DataLayout &DL, SetVector< Value *> &Explored)
	Returns a re-written value of Start as an indexed GEP using Base as a pointer. More...

static std::pair< Value , Value >	getAsConstantIndexedAddress (Value *V, const DataLayout &DL)
	Looks through GEPs, IntToPtrInsts and PtrToIntInsts in order to express the input Value as a constant indexed GEP. More...

static Instruction *	transformToIndexedCompare (GEPOperator GEPLHS, Value RHS, ICmpInst::Predicate Cond, const DataLayout &DL)
	Converts (CMP GEPLHS, RHS) if this change would make RHS a constant. More...

static Instruction *	processUGT_ADDCST_ADD (ICmpInst &I, Value A, Value B, ConstantInt CI2, ConstantInt CI1, InstCombiner &IC)
	The caller has matched a pattern of the form: I = icmp ugt (add (add A, B), CI2), CI1 If this is of the form: sum = a + b if (sum+128 >u 255) Then replace it with llvm.sadd.with.overflow.i8. More...

static Instruction *	foldICmpShlOne (ICmpInst &Cmp, Instruction *Shl, const APInt &C)
	Fold icmp (shl 1, Y), C. More...

static Value *	foldICmpWithLowBitMaskedVal (ICmpInst &I, InstCombiner::BuilderTy &Builder)
	Some comparisons can be simplified. More...

static Value *	foldICmpWithTruncSignExtendedVal (ICmpInst &I, InstCombiner::BuilderTy &Builder)
	Some comparisons can be simplified. More...

static Instruction *	foldICmpWithMinMax (ICmpInst &Cmp)
	Fold icmp Pred min\|max(X, Y), X. More...

static Instruction *	processUMulZExtIdiom (ICmpInst &I, Value MulVal, Value OtherVal, InstCombiner &IC)
	Recognize and process idiom involving test for multiplication overflow. More...

static APInt	getDemandedBitsLHSMask (ICmpInst &I, unsigned BitWidth)
	When performing a comparison against a constant, it is possible that not all the bits in the LHS are demanded. More...

static bool	swapMayExposeCSEOpportunities (const Value Op0, const Value Op1)
	Check if the order of `Op0` and `Op1` as operands in an ICmpInst should be swapped. More...

static bool	isChainSelectCmpBranch (const SelectInst *SI)
	Return true when the instruction sequence within a block is select-cmp-br. More...

static ICmpInst *	canonicalizeCmpWithConstant (ICmpInst &I)
	If we have an icmp le or icmp ge instruction with a constant operand, turn it into the appropriate icmp lt or icmp gt instruction. More...

static Instruction *	canonicalizeICmpBool (ICmpInst &I, InstCombiner::BuilderTy &Builder)
	Integer compare with boolean values can always be turned into bitwise ops. More...

static Instruction *	foldICmpWithHighBitMask (ICmpInst &Cmp, InstCombiner::BuilderTy &Builder)

static Instruction *	foldVectorCmp (CmpInst &Cmp, InstCombiner::BuilderTy &Builder)

static Instruction *	foldFCmpReciprocalAndZero (FCmpInst &I, Instruction LHSI, Constant RHSC)
	Fold (C / X) < 0.0 –> X < 0.0 if possible. Swap predicate if necessary. More...

static Instruction *	foldFabsWithFcmpZero (FCmpInst &I)
	Optimize fabs(X) compared with zero. More...

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE "instcombine"

Definition at line 32 of file InstCombineCompares.cpp.

Function Documentation

◆ addWithOverflow()

static bool addWithOverflow	(	APInt &	Result,
		const APInt &	In1,
		const APInt &	In2,
		bool	IsSigned = `false`
	)

static

Compute Result = In1+In2, returning true if the result overflowed for this type.

Definition at line 40 of file InstCombineCompares.cpp.

References llvm::APInt::sadd_ov(), and llvm::APInt::uadd_ov().

Referenced by foldICmpShlOne().

◆ canonicalizeCmpWithConstant()

static ICmpInst* canonicalizeCmpWithConstant ( ICmpInst & I )

static

If we have an icmp le or icmp ge instruction with a constant operand, turn it into the appropriate icmp lt or icmp gt instruction.

This transform allows them to be folded in visitICmpInst.

Definition at line 4557 of file InstCombineCompares.cpp.

References assert(), llvm::dyn_cast(), llvm::ConstantInt::get(), llvm::ConstantExpr::getAdd(), llvm::Constant::getAggregateElement(), llvm::User::getOperand(), llvm::CmpInst::getPredicate(), llvm::ICmpInst::getSignedPredicate(), llvm::Value::getType(), llvm::Type::getVectorNumElements(), llvm::CmpInst::ICMP_SGE, llvm::CmpInst::ICMP_SLE, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULE, llvm::CmpInst::ICMP_ULT, llvm::CmpInst::isSigned(), and llvm::Type::isVectorTy().

Referenced by llvm::InstCombiner::visitICmpInst().

◆ canonicalizeICmpBool()

static Instruction* canonicalizeICmpBool	(	ICmpInst &	I,
		InstCombiner::BuilderTy &	Builder
	)

static

Integer compare with boolean values can always be turned into bitwise ops.

Definition at line 4613 of file InstCombineCompares.cpp.

References assert(), B, llvm::BinaryOperator::CreateNot(), llvm::IRBuilder< T, Inserter >::CreateNot(), llvm::IRBuilder< T, Inserter >::CreateXor(), llvm::User::getOperand(), llvm::CmpInst::getPredicate(), llvm::Value::getType(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_SGE, llvm::CmpInst::ICMP_SGT, llvm::CmpInst::ICMP_SLE, llvm::CmpInst::ICMP_SLT, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULE, llvm::CmpInst::ICMP_ULT, llvm::Type::isIntOrIntVectorTy(), LLVM_FALLTHROUGH, llvm_unreachable, llvm::PatternMatch::m_One(), llvm::PatternMatch::m_Zero(), llvm::PatternMatch::match(), and std::swap().

Referenced by llvm::InstCombiner::visitICmpInst().

◆ canRewriteGEPAsOffset()

static bool canRewriteGEPAsOffset	(	Value *	Start,
		Value *	Base,
		const DataLayout &	DL,
		SetVector< Value *> &	Explored
	)

static

Returns true if we can rewrite Start as a GEP with pointer Base and some integer offset.

The nodes that need to be re-written for this transformation will be added to Explored.

Definition at line 548 of file InstCombineCompares.cpp.

Referenced by transformToIndexedCompare().

◆ computeSignedMinMaxValuesFromKnownBits()

static void computeSignedMinMaxValuesFromKnownBits	(	const KnownBits &	Known,
		APInt &	Min,
		APInt &	Max
	)

static

Given a signed integer type and a set of known zero and one bits, compute the maximum and minimum values that could have the specified known zero and known one bits, returning them in Min/Max.

TODO: Move to method on KnownBits struct?

Definition at line 131 of file InstCombineCompares.cpp.

References assert(), llvm::APInt::clearSignBit(), llvm::KnownBits::getBitWidth(), llvm::APInt::getBitWidth(), llvm::KnownBits::One, llvm::APInt::setSignBit(), and llvm::KnownBits::Zero.

Referenced by llvm::InstCombiner::replacedSelectWithOperand().

◆ computeUnsignedMinMaxValuesFromKnownBits()

static void computeUnsignedMinMaxValuesFromKnownBits	(	const KnownBits &	Known,
		APInt &	Min,
		APInt &	Max
	)

static

Given an unsigned integer type and a set of known zero and one bits, compute the maximum and minimum values that could have the specified known zero and known one bits, returning them in Min/Max.

TODO: Move to method on KnownBits struct?

Definition at line 153 of file InstCombineCompares.cpp.

References assert(), C, llvm::ConstantFoldCompareInstOperands(), llvm::dyn_cast(), llvm::SmallVectorBase::empty(), GEP, llvm::ConstantInt::get(), llvm::Constant::getAggregateElement(), llvm::ConstantExpr::getAnd(), llvm::Type::getArrayElementType(), llvm::Type::getArrayNumElements(), llvm::KnownBits::getBitWidth(), llvm::APInt::getBitWidth(), llvm::ConstantExpr::getExtractValue(), llvm::GlobalVariable::getInitializer(), llvm::Type::getIntegerBitWidth(), llvm::User::getNumOperands(), llvm::User::getOperand(), llvm::CmpInst::getPredicate(), llvm::Type::getPrimitiveSizeInBits(), llvm::Value::getType(), llvm::ConstantInt::getZExtValue(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::GetElementPtrInst::isInBounds(), isZero(), llvm::KnownBits::One, llvm::SmallVectorTemplateBase< T, bool >::push_back(), and llvm::KnownBits::Zero.

Referenced by llvm::InstCombiner::replacedSelectWithOperand().

◆ evaluateGEPOffsetExpression()

static Value* evaluateGEPOffsetExpression	(	User *	GEP,
		InstCombiner &	IC,
		const DataLayout &	DL
	)

static

Return a value that can be used to compare the offset implied by a GEP to zero.

For example, if we have &A[i], we want to return 'i' for "icmp ne i, 0". Note that, in general, indices can be complex, and scales are involved. The above expression would also be legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32). This latter form is less amenable to optimization though, and we are allowed to generate the first by knowing that pointer arithmetic doesn't overflow.

If we can't emit an optimized form for this expression, this returns null.

Definition at line 454 of file InstCombineCompares.cpp.

References llvm::InstCombiner::Builder, llvm::IRBuilder< T, Inserter >::CreateAdd(), llvm::IRBuilder< T, Inserter >::CreateIntCast(), llvm::IRBuilder< T, Inserter >::CreateTrunc(), llvm::dyn_cast(), llvm::gep_type_begin(), llvm::ConstantInt::get(), llvm::StructLayout::getElementOffset(), llvm::generic_gep_type_iterator< ItTy >::getIndexedType(), llvm::Type::getIntegerBitWidth(), llvm::DataLayout::getIntPtrType(), llvm::User::getNumOperands(), llvm::User::getOperand(), llvm::Type::getPrimitiveSizeInBits(), llvm::ConstantInt::getSExtValue(), llvm::DataLayout::getStructLayout(), llvm::generic_gep_type_iterator< ItTy >::getStructTypeOrNull(), llvm::Value::getType(), llvm::DataLayout::getTypeAllocSize(), llvm::ConstantInt::getZExtValue(), llvm::ConstantInt::isZero(), llvm::SignExtend64(), and Size.

Referenced by transformToIndexedCompare().

◆ foldFabsWithFcmpZero()

static Instruction* foldFabsWithFcmpZero ( FCmpInst & I )

static

◆ foldFCmpReciprocalAndZero()

static Instruction* foldFCmpReciprocalAndZero	(	FCmpInst &	I,
		Instruction *	LHSI,
		Constant *	RHSC
	)

static

Fold (C / X) < 0.0 –> X < 0.0 if possible. Swap predicate if necessary.

Definition at line 5286 of file InstCombineCompares.cpp.

References C, llvm::CmpInst::FCMP_OGE, llvm::CmpInst::FCMP_OGT, llvm::CmpInst::FCMP_OLE, llvm::CmpInst::FCMP_OLT, llvm::User::getOperand(), llvm::CmpInst::getPredicate(), llvm::CmpInst::getSwappedPredicate(), llvm::Instruction::hasNoInfs(), I, llvm::APFloat::isNegative(), llvm::APFloat::isZero(), llvm::PatternMatch::m_AnyZeroFP(), llvm::PatternMatch::m_APFloat(), and llvm::PatternMatch::match().

Referenced by llvm::InstCombiner::visitFCmpInst().

◆ foldICmpShlOne()

static Instruction* foldICmpShlOne	(	ICmpInst &	Cmp,
		Instruction *	Shl,
		const APInt &	C
	)

static

Fold icmp (shl 1, Y), C.

Definition at line 1837 of file InstCombineCompares.cpp.

◆ foldICmpWithHighBitMask()

static Instruction* foldICmpWithHighBitMask	(	ICmpInst &	Cmp,
		InstCombiner::BuilderTy &	Builder
	)

static

◆ foldICmpWithLowBitMaskedVal()

static Value* foldICmpWithLowBitMaskedVal	(	ICmpInst &	I,
		InstCombiner::BuilderTy &	Builder
	)

static

Some comparisons can be simplified.

In this case, we are looking for comparisons that look like a check for a lossy truncation. Folds: icmp SrcPred (x & Mask), x to icmp DstPred x, Mask Where Mask is some pattern that produces all-ones in low bits: (-1 >> y) ((-1 << y) >> y) <- non-canonical, has extra uses ~(-1 << y) ((1 << y) + (-1)) <- non-canonical, has extra uses The Mask can be a constant, too. For some predicates, the operands are commutative. For others, x can only be on a specific side.

Definition at line 2937 of file InstCombineCompares.cpp.

Referenced by foldICmpWithTruncSignExtendedVal().

◆ foldICmpWithMinMax()

static Instruction* foldICmpWithMinMax ( ICmpInst & Cmp )

static

Fold icmp Pred min|max(X, Y), X.

Definition at line 3455 of file InstCombineCompares.cpp.

Referenced by llvm::InstCombiner::visitICmpInst().

◆ foldICmpWithTruncSignExtendedVal()

static Value* foldICmpWithTruncSignExtendedVal	(	ICmpInst &	I,
		InstCombiner::BuilderTy &	Builder
	)

static

Some comparisons can be simplified.

In this case, we are looking for comparisons that look like a check for a lossy signed truncation. Folds: (MaskedBits is a constant.) ((x << MaskedBits) a>> MaskedBits) SrcPred x Into: (add x, (1 << (KeptBits-1))) DstPred (1 << KeptBits) Where KeptBits = bitwidth(x) - MaskedBits

Definition at line 3030 of file InstCombineCompares.cpp.

References llvm::APInt::abs(), llvm::MCID::Add, assert(), B, C, llvm::APInt::countTrailingZeros(), llvm::IRBuilder< T, Inserter >::CreateAdd(), llvm::IRBuilder< T, Inserter >::CreateICmp(), D, llvm::dyn_cast(), foldICmpWithLowBitMaskedVal(), llvm::ConstantInt::get(), llvm::Constant::getAllOnesValue(), llvm::APInt::getBitWidth(), llvm::ConstantInt::getFalse(), llvm::APInt::getLowBitsSet(), llvm::ConstantExpr::getNeg(), llvm::Constant::getNullValue(), llvm::BinaryOperator::getOpcode(), llvm::User::getOperand(), llvm::CmpInst::getPredicate(), llvm::Type::getScalarSizeInBits(), llvm::ICmpInst::getSignedPredicate(), llvm::CmpInst::getSwappedPredicate(), llvm::ConstantInt::getTrue(), llvm::Value::getType(), llvm::ICmpInst::getUnsignedPredicate(), llvm::Instruction::hasNoSignedWrap(), llvm::Instruction::hasNoUnsignedWrap(), llvm::Value::hasOneUse(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_SGE, llvm::CmpInst::ICMP_SGT, llvm::CmpInst::ICMP_SLE, llvm::CmpInst::ICMP_SLT, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULE, llvm::CmpInst::ICMP_ULT, llvm::ICmpInst::isEquality(), llvm::Instruction::isExact(), llvm::APInt::isMaxSignedValue(), llvm::APInt::isNegative(), llvm::APInt::isNullValue(), llvm::APInt::isOneValue(), llvm::CmpInst::isSigned(), llvm::APInt::isSignMask(), llvm::CmpInst::isUnsigned(), llvm::APInt::lshr(), llvm::PatternMatch::m_Add(), llvm::PatternMatch::m_AllOnes(), llvm::PatternMatch::m_APInt(), llvm::PatternMatch::m_AShr(), llvm::PatternMatch::m_c_Add(), llvm::PatternMatch::m_c_And(), llvm::PatternMatch::m_c_ICmp(), llvm::PatternMatch::m_Deferred(), llvm::PatternMatch::m_Neg(), llvm::PatternMatch::m_One(), llvm::PatternMatch::m_OneUse(), llvm::PatternMatch::m_Shl(), llvm::PatternMatch::m_Specific(), llvm::PatternMatch::m_Value(), llvm::BitmaskEnumDetail::Mask(), llvm::PatternMatch::match(), llvm::APInt::shl(), T1, llvm::APInt::uge(), llvm::APInt::ugt(), X, and Y.

◆ foldVectorCmp()

static Instruction* foldVectorCmp	(	CmpInst &	Cmp,
		InstCombiner::BuilderTy &	Builder
	)

static

Definition at line 4743 of file InstCombineCompares.cpp.

References llvm::IRBuilder< T, Inserter >::CreateFCmp(), llvm::IRBuilder< T, Inserter >::CreateICmp(), llvm::UndefValue::get(), llvm::User::getOperand(), llvm::CmpInst::getPredicate(), llvm::Value::getType(), llvm::Value::hasOneUse(), llvm::PatternMatch::m_Constant(), llvm::PatternMatch::m_ShuffleVector(), llvm::PatternMatch::m_Specific(), llvm::PatternMatch::m_Undef(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), P, and llvm::NVPTX::PTXLdStInstCode::V2.

Referenced by llvm::InstCombiner::visitFCmpInst(), and llvm::InstCombiner::visitICmpInst().

◆ getAsConstantIndexedAddress()

static std::pair<Value , Value > getAsConstantIndexedAddress	(	Value *	V,
		const DataLayout &	DL
	)

static

Looks through GEPs, IntToPtrInsts and PtrToIntInsts in order to express the input Value as a constant indexed GEP.

Returns a pair containing the GEPs Pointer and Index.

Definition at line 789 of file InstCombineCompares.cpp.

References llvm::IntegerType::get(), llvm::ConstantExpr::getAdd(), llvm::Value::getContext(), llvm::DataLayout::getIndexTypeSizeInBits(), llvm::Constant::getNullValue(), llvm::GetElementPtrInst::getNumIndices(), llvm::User::getOperand(), llvm::ConstantExpr::getSExtOrBitCast(), llvm::Value::getType(), llvm::GetElementPtrInst::hasAllConstantIndices(), and llvm::GetElementPtrInst::isInBounds().

Referenced by transformToIndexedCompare().

◆ getDemandedBitsLHSMask()

static APInt getDemandedBitsLHSMask	(	ICmpInst &	I,
		unsigned	BitWidth
	)

static

When performing a comparison against a constant, it is possible that not all the bits in the LHS are demanded.

This helper method computes the mask that IS demanded.

Definition at line 4160 of file InstCombineCompares.cpp.

References llvm::APInt::countTrailingOnes(), llvm::APInt::countTrailingZeros(), llvm::APInt::getAllOnesValue(), llvm::APInt::getBitsSetFrom(), llvm::User::getOperand(), llvm::CmpInst::getPredicate(), llvm::APInt::getSignMask(), llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULT, isSignBitCheck(), llvm::PatternMatch::m_APInt(), and llvm::PatternMatch::match().

Referenced by llvm::InstCombiner::replacedSelectWithOperand().

◆ hasBranchUse()

static bool hasBranchUse ( ICmpInst & I )

static

Given an icmp instruction, return true if any use of this comparison is a branch on sign bit comparison.

Definition at line 66 of file InstCombineCompares.cpp.

References llvm::Value::users().

Referenced by processUGT_ADDCST_ADD().

◆ isChainSelectCmpBranch()

static bool isChainSelectCmpBranch ( const SelectInst * SI )

static

Return true when the instruction sequence within a block is select-cmp-br.

Definition at line 4247 of file InstCombineCompares.cpp.

References llvm::dyn_cast(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::BasicBlock::getTerminator(), and SI.

Referenced by llvm::InstCombiner::replacedSelectWithOperand().

◆ isSignBitCheck()

static bool isSignBitCheck	(	ICmpInst::Predicate	Pred,
		const APInt &	RHS,
		bool &	TrueIfSigned
	)

static

Given an exploded icmp instruction, return true if the comparison only checks the sign bit.

If it only checks the sign bit, set TrueIfSigned if the result of the comparison is true when the input value is signed.

Definition at line 76 of file InstCombineCompares.cpp.

References llvm::CmpInst::ICMP_SGT, llvm::CmpInst::ICMP_SLE, llvm::CmpInst::ICMP_SLT, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_UGT, llvm::APInt::isAllOnesValue(), llvm::APInt::isMaxSignedValue(), llvm::APInt::isNullValue(), and llvm::APInt::isSignMask().

Referenced by foldICmpShlOne(), getDemandedBitsLHSMask(), and processUGT_ADDCST_ADD().

◆ isSignTest()

static bool isSignTest	(	ICmpInst::Predicate &	Pred,
		const APInt &	C
	)

static

Returns true if the exploded icmp can be expressed as a signed comparison to zero and updates the predicate accordingly.

The signedness of the comparison is preserved. TODO: Refactor with decomposeBitTestICmp()?

Definition at line 105 of file InstCombineCompares.cpp.

References llvm::CmpInst::ICMP_SGE, llvm::CmpInst::ICMP_SGT, llvm::CmpInst::ICMP_SLE, llvm::CmpInst::ICMP_SLT, llvm::APInt::isAllOnesValue(), llvm::APInt::isNullValue(), llvm::APInt::isOneValue(), llvm::ICmpInst::isRelational(), and llvm::CmpInst::isSigned().

Referenced by foldICmpShlOne(), and processUGT_ADDCST_ADD().

◆ processUGT_ADDCST_ADD()

static Instruction* processUGT_ADDCST_ADD	(	ICmpInst &	I,
		Value *	A,
		Value *	B,
		ConstantInt *	CI2,
		ConstantInt *	CI1,
		InstCombiner &	IC
	)

static

The caller has matched a pattern of the form: I = icmp ugt (add (add A, B), CI2), CI1 If this is of the form: sum = a + b if (sum+128 >u 255) Then replace it with llvm.sadd.with.overflow.i8.

Definition at line 1235 of file InstCombineCompares.cpp.

◆ processUMulZExtIdiom()

static Instruction* processUMulZExtIdiom	(	ICmpInst &	I,
		Value *	MulVal,
		Value *	OtherVal,
		InstCombiner &	IC
	)

static

Recognize and process idiom involving test for multiplication overflow.

The caller has matched a pattern of the form: I = cmp u (mul(zext A, zext B), V The function checks if this is a test for overflow and if so replaces multiplication with call to 'mul.with.overflow' intrinsic.

Parameters

I	Compare instruction.
MulVal	Result of 'mult' instruction. It is one of the arguments of the compare instruction. Must be of integer type.
OtherVal	The other argument of compare instruction.

Returns: Instruction which must replace the compare instruction, NULL if no replacement required.

Definition at line 3930 of file InstCombineCompares.cpp.

References llvm::InstCombineWorklist::Add(), assert(), B, llvm::InstCombiner::Builder, llvm::APInt::countLeadingZeros(), llvm::ExtractValueInst::Create(), llvm::IRBuilder< T, Inserter >::CreateAnd(), llvm::IRBuilder< T, Inserter >::CreateCall(), llvm::IRBuilder< T, Inserter >::CreateExtractValue(), llvm::BinaryOperator::CreateNot(), llvm::IRBuilder< T, Inserter >::CreateZExt(), llvm::dyn_cast(), llvm::APInt::eq(), F(), llvm::ConstantInt::getBitWidth(), llvm::APInt::getBitWidth(), llvm::Intrinsic::getDeclaration(), llvm::APInt::getMaxValue(), llvm::Instruction::getModule(), llvm::APInt::getOneBitSet(), llvm::BinaryOperator::getOpcode(), llvm::User::getOperand(), llvm::CmpInst::getPredicate(), llvm::Type::getPrimitiveSizeInBits(), llvm::Value::getType(), llvm::ConstantInt::getValue(), llvm::Value::hasNUsesOrMore(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULE, llvm::CmpInst::ICMP_ULT, llvm::APInt::isPowerOf2(), llvm_unreachable, llvm::APInt::logBase2(), llvm::PatternMatch::m_And(), llvm::PatternMatch::m_ConstantInt(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::InstCombiner::replaceInstUsesWith(), llvm::IRBuilderBase::SetInsertPoint(), llvm::User::setOperand(), llvm::APInt::trunc(), llvm::Intrinsic::umul_with_overflow, llvm::Value::user_begin(), llvm::Value::user_end(), llvm::Value::users(), llvm::InstCombiner::Worklist, and llvm::APInt::zext().

Referenced by llvm::InstCombiner::visitICmpInst().

◆ rewriteGEPAsOffset()

static Value* rewriteGEPAsOffset	(	Value *	Start,
		Value *	Base,
		const DataLayout &	DL,
		SetVector< Value *> &	Explored
	)

static

Returns a re-written value of Start as an indexed GEP using Base as a pointer.

Definition at line 672 of file InstCombineCompares.cpp.

Referenced by transformToIndexedCompare().

◆ setInsertionPoint()

static void setInsertionPoint	(	IRBuilder<> &	Builder,
		Value *	V,
		bool	Before = `true`
	)

static

Definition at line 647 of file InstCombineCompares.cpp.

References assert(), llvm::BasicBlock::getFirstInsertionPt(), I, and llvm::IRBuilderBase::SetInsertPoint().

◆ STATISTIC()

STATISTIC	(	NumSel	,
		"Number of select opts"
	)

◆ subWithOverflow()

static bool subWithOverflow	(	APInt &	Result,
		const APInt &	In1,
		const APInt &	In2,
		bool	IsSigned = `false`
	)

static

Compute Result = In1-In2, returning true if the result overflowed for this type.

Definition at line 53 of file InstCombineCompares.cpp.

References llvm::APInt::ssub_ov(), and llvm::APInt::usub_ov().

Referenced by foldICmpShlOne().

◆ swapMayExposeCSEOpportunities()

static bool swapMayExposeCSEOpportunities	(	const Value *	Op0,
		const Value *	Op1
	)

static

Check if the order of Op0 and Op1 as operands in an ICmpInst should be swapped.

The decision is based on how many times these two operands are reused as subtract operands and their positions in those instructions. The rationale is that several architectures use the same instruction for both subtract and cmp. Thus, it is better if the order of those operands match.

Returns: true if Op0 and Op1 should be swapped.

Definition at line 4197 of file InstCombineCompares.cpp.

References llvm::Value::getType(), llvm::Type::isPointerTy(), llvm::PatternMatch::m_Specific(), llvm::PatternMatch::m_Sub(), llvm::PatternMatch::match(), and llvm::Value::users().

Referenced by llvm::InstCombiner::visitICmpInst().

◆ transformToIndexedCompare()

static Instruction* transformToIndexedCompare	(	GEPOperator *	GEPLHS,
		Value *	RHS,
		ICmpInst::Predicate	Cond,
		const DataLayout &	DL
	)

static

Converts (CMP GEPLHS, RHS) if this change would make RHS a constant.

We can look through PHIs, GEPs and casts in order to determine a common base between GEPLHS and RHS.

Definition at line 830 of file InstCombineCompares.cpp.

Macros

Functions

Macro Definition Documentation

◆ DEBUG_TYPE

Function Documentation

◆ addWithOverflow()

◆ canonicalizeCmpWithConstant()

◆ canonicalizeICmpBool()

◆ canRewriteGEPAsOffset()

◆ computeSignedMinMaxValuesFromKnownBits()

◆ computeUnsignedMinMaxValuesFromKnownBits()

◆ evaluateGEPOffsetExpression()

◆ foldFabsWithFcmpZero()

◆ foldFCmpReciprocalAndZero()

◆ foldICmpShlOne()

◆ foldICmpWithHighBitMask()

◆ foldICmpWithLowBitMaskedVal()

◆ foldICmpWithMinMax()

◆ foldICmpWithTruncSignExtendedVal()

◆ foldVectorCmp()

◆ getAsConstantIndexedAddress()

◆ getDemandedBitsLHSMask()

◆ hasBranchUse()

◆ isChainSelectCmpBranch()

◆ isSignBitCheck()

◆ isSignTest()

◆ processUGT_ADDCST_ADD()

◆ processUMulZExtIdiom()

◆ rewriteGEPAsOffset()

◆ setInsertionPoint()

◆ STATISTIC()

◆ subWithOverflow()

◆ swapMayExposeCSEOpportunities()

◆ transformToIndexedCompare()