InstCombineCompares.cpp File Reference

#include "InstCombineInternal.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/CmpInstAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/VectorUtils.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/KnownBits.h"
#include "llvm/Transforms/InstCombine/InstCombiner.h"

Include dependency graph for InstCombineCompares.cpp:

Go to the source code of this file.

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.
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.
static bool	hasBranchUse (ICmpInst &I)
	Given an icmp instruction, return true if any use of this comparison is a branch on sign bit comparison.
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.
static bool	canRewriteGEPAsOffset (Type *ElemTy, 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.
static void	setInsertionPoint (IRBuilder<> &Builder, Value *V, bool Before=true)
static Value *	rewriteGEPAsOffset (Type *ElemTy, 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.
static std::pair< Value *, Value * >	getAsConstantIndexedAddress (Type *ElemTy, Value *V, const DataLayout &DL)
	Looks through GEPs, IntToPtrInsts and PtrToIntInsts in order to express the input Value as a constant indexed GEP.
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.
static Instruction *	processUGT_ADDCST_ADD (ICmpInst &I, Value *A, Value *B, ConstantInt *CI2, ConstantInt *CI1, InstCombinerImpl &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.
static Instruction *	foldICmpShlOne (ICmpInst &Cmp, Instruction *Shl, const APInt &C)
	Fold icmp (shl 1, Y), C.
static Instruction *	foldICmpIntrinsicWithIntrinsic (ICmpInst &Cmp)
	Fold an icmp with LLVM intrinsics.
static Value *	foldICmpWithLowBitMaskedVal (ICmpInst &I, InstCombiner::BuilderTy &Builder)
	Some comparisons can be simplified.
static Value *	foldICmpWithTruncSignExtendedVal (ICmpInst &I, InstCombiner::BuilderTy &Builder)
	Some comparisons can be simplified.
static Value *	foldShiftIntoShiftInAnotherHandOfAndInICmp (ICmpInst &I, const SimplifyQuery SQ, InstCombiner::BuilderTy &Builder)
static Instruction *	foldICmpXNegX (ICmpInst &I)
static Instruction *	foldICmpWithMinMax (ICmpInst &Cmp)
	Fold icmp Pred min|max(X, Y), X.
static bool	isNeutralValue (Instruction::BinaryOps BinaryOp, Value *RHS, bool IsSigned)
static Instruction *	processUMulZExtIdiom (ICmpInst &I, Value *MulVal, Value *OtherVal, InstCombinerImpl &IC)
	Recognize and process idiom involving test for multiplication overflow.
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.
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.
static bool	isChainSelectCmpBranch (const SelectInst *SI)
	Return true when the instruction sequence within a block is select-cmp-br.
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.
static Instruction *	canonicalizeICmpBool (ICmpInst &I, InstCombiner::BuilderTy &Builder)
	Integer compare with boolean values can always be turned into bitwise ops.
static Instruction *	foldICmpWithHighBitMask (ICmpInst &Cmp, InstCombiner::BuilderTy &Builder)
static Instruction *	foldVectorCmp (CmpInst &Cmp, InstCombiner::BuilderTy &Builder)
static Instruction *	foldICmpOfUAddOv (ICmpInst &I)
static Instruction *	foldICmpInvariantGroup (ICmpInst &I)
static Instruction *	foldReductionIdiom (ICmpInst &I, InstCombiner::BuilderTy &Builder, const DataLayout &DL)
	This function folds patterns produced by lowering of reduce idioms, such as llvm.vector.reduce.and which are lowered into instruction chains.
static Instruction *	foldFCmpReciprocalAndZero (FCmpInst &I, Instruction *LHSI, Constant *RHSC)
	Fold (C / X) < 0.0 --> X < 0.0 if possible. Swap predicate if necessary.
static Instruction *	foldFabsWithFcmpZero (FCmpInst &I, InstCombinerImpl &IC)
	Optimize fabs(X) compared with zero.
static Instruction *	foldFCmpFNegCommonOp (FCmpInst &I)

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "instcombine"

Definition at line 33 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 41 of file InstCombineCompares.cpp.

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

Referenced by llvm::InstCombinerImpl::foldICmpDivConstant().

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 5992 of file InstCombineCompares.cpp.

References llvm::InstCombiner::getFlippedStrictnessPredicateAndConstant(), I, llvm::InstCombiner::isCanonicalPredicate(), llvm::ICmpInst::isEquality(), and llvm::CmpInst::isIntPredicate().

Referenced by llvm::InstCombinerImpl::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 6036 of file InstCombineCompares.cpp.

References A, assert(), B, Builder, llvm::BinaryOperator::CreateNot(), I, 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_unreachable, llvm::PatternMatch::m_One(), llvm::PatternMatch::m_Zero(), llvm::PatternMatch::match(), and std::swap().

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

canRewriteGEPAsOffset()

static bool canRewriteGEPAsOffset ( Type *  ElemTy, 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 411 of file InstCombineCompares.cpp.

References llvm::SmallVectorTemplateCommon< T, typename >::back(), llvm::sampleprof::Base, llvm::SetVector< T, Vector, Set >::contains(), DL, llvm::SmallVectorBase< Size_T >::empty(), GEP, llvm::SetVector< T, Vector, Set >::insert(), PHI, llvm::SmallVectorTemplateBase< T, bool >::pop_back(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::SetVector< T, Vector, Set >::size(), and llvm::Value::uses().

Referenced by transformToIndexedCompare().

foldFabsWithFcmpZero()

static Instruction * foldFabsWithFcmpZero ( FCmpInst &  I, InstCombinerImpl &  IC  )

static

Optimize fabs(X) compared with zero.

Definition at line 6868 of file InstCombineCompares.cpp.

References assert(), llvm::CallingConv::C, F, llvm::CmpInst::FCMP_OEQ, llvm::CmpInst::FCMP_OGE, llvm::CmpInst::FCMP_OGT, llvm::CmpInst::FCMP_OLE, llvm::CmpInst::FCMP_OLT, llvm::CmpInst::FCMP_ONE, llvm::CmpInst::FCMP_ORD, llvm::CmpInst::FCMP_UEQ, llvm::CmpInst::FCMP_UGE, llvm::CmpInst::FCMP_UGT, llvm::CmpInst::FCMP_ULE, llvm::CmpInst::FCMP_ULT, llvm::CmpInst::FCMP_UNE, llvm::CmpInst::FCMP_UNO, llvm::Constant::getNullValue(), I, llvm_unreachable, llvm::PatternMatch::m_APFloat(), llvm::PatternMatch::m_FAbs(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), P, llvm::DenormalMode::PositiveZero, llvm::DenormalMode::PreserveSign, llvm::InstCombiner::replaceOperand(), and X.

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

foldFCmpFNegCommonOp()

static Instruction * foldFCmpFNegCommonOp ( FCmpInst &  I )

static

Definition at line 6968 of file InstCombineCompares.cpp.

References llvm::Constant::getNullValue(), llvm::Value::getType(), I, llvm::PatternMatch::m_FNeg(), llvm::PatternMatch::m_Specific(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), and std::swap().

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

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 6821 of file InstCombineCompares.cpp.

References llvm::CallingConv::C, llvm::CmpInst::FCMP_OGE, llvm::CmpInst::FCMP_OGT, llvm::CmpInst::FCMP_OLE, llvm::CmpInst::FCMP_OLT, llvm::User::getOperand(), llvm::Instruction::hasNoInfs(), I, llvm::PatternMatch::m_AnyZeroFP(), llvm::PatternMatch::m_APFloat(), and llvm::PatternMatch::match().

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

foldICmpIntrinsicWithIntrinsic()

static Instruction * foldICmpIntrinsicWithIntrinsic ( ICmpInst &  Cmp )

static

Fold an icmp with LLVM intrinsics.

Definition at line 3356 of file InstCombineCompares.cpp.

References assert().

Referenced by llvm::InstCombinerImpl::foldICmpEquality().

foldICmpInvariantGroup()

static Instruction * foldICmpInvariantGroup ( ICmpInst &  I )

static

Definition at line 6256 of file InstCombineCompares.cpp.

References llvm::CmpInst::Create(), I, llvm::PatternMatch::m_Instruction(), llvm::PatternMatch::m_Zero(), llvm::PatternMatch::match(), and llvm::NullPointerIsDefined().

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

foldICmpOfUAddOv()

static Instruction * foldICmpOfUAddOv ( ICmpInst &  I )

static

Definition at line 6228 of file InstCombineCompares.cpp.

References A, B, llvm::ExtractValueInst::Create(), I, llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULT, llvm::PatternMatch::m_AllOnes(), llvm::PatternMatch::m_One(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::m_ZeroInt(), and llvm::PatternMatch::match().

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

foldICmpShlOne()

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

static

Fold icmp (shl 1, Y), C.

Definition at line 2078 of file InstCombineCompares.cpp.

References llvm::CallingConv::C, llvm::ConstantInt::get(), llvm::Value::getType(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_SGT, llvm::CmpInst::ICMP_SLT, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULE, llvm::CmpInst::ICMP_ULT, llvm::PatternMatch::m_One(), llvm::PatternMatch::m_Shl(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), and Y.

Referenced by llvm::InstCombinerImpl::foldICmpShlConstant().

foldICmpWithHighBitMask()

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

static

Definition at line 6115 of file InstCombineCompares.cpp.

References Builder, llvm::CmpInst::Create(), llvm::Constant::getNullValue(), llvm::Value::getType(), 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::PatternMatch::m_Add(), llvm::PatternMatch::m_AllOnes(), llvm::PatternMatch::m_c_ICmp(), llvm::PatternMatch::m_CombineOr(), llvm::PatternMatch::m_Not(), llvm::PatternMatch::m_One(), llvm::PatternMatch::m_OneUse(), llvm::PatternMatch::m_Shl(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), X, and Y.

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

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 3660 of file InstCombineCompares.cpp.

References assert(), Builder, llvm::Constant::getAggregateElement(), I, 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_unreachable, llvm::PatternMatch::m_Add(), llvm::PatternMatch::m_AllOnes(), llvm::PatternMatch::m_c_And(), llvm::PatternMatch::m_c_ICmp(), llvm::PatternMatch::m_CombineAnd(), llvm::PatternMatch::m_CombineOr(), llvm::PatternMatch::m_Constant(), llvm::PatternMatch::m_Deferred(), llvm::PatternMatch::m_LowBitMask(), llvm::PatternMatch::m_LShr(), llvm::PatternMatch::m_NonNegative(), llvm::PatternMatch::m_Not(), llvm::PatternMatch::m_One(), llvm::PatternMatch::m_Shl(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::Constant::replaceUndefsWith(), X, and Y.

Referenced by llvm::InstCombinerImpl::foldICmpBinOp().

foldICmpWithMinMax()

static Instruction * foldICmpWithMinMax ( ICmpInst &  Cmp )

static

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

Definition at line 4557 of file InstCombineCompares.cpp.

References 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::PatternMatch::m_c_SMax(), llvm::PatternMatch::m_c_SMin(), llvm::PatternMatch::m_c_UMax(), llvm::PatternMatch::m_c_UMin(), llvm::PatternMatch::m_Specific(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), std::swap(), X, and Y.

Referenced by llvm::InstCombinerImpl::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 3754 of file InstCombineCompares.cpp.

References assert(), llvm::BitWidth, Builder, llvm::ConstantInt::get(), I, llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_ULT, llvm::APInt::isPowerOf2(), llvm::APInt::lshr(), llvm::PatternMatch::m_APInt(), llvm::PatternMatch::m_AShr(), llvm::PatternMatch::m_c_ICmp(), llvm::PatternMatch::m_Deferred(), llvm::PatternMatch::m_OneUse(), llvm::PatternMatch::m_Shl(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::APInt::shl(), T1, llvm::APInt::ugt(), llvm::APInt::ult(), and X.

Referenced by llvm::InstCombinerImpl::foldICmpBinOp().

foldICmpXNegX()

static Instruction * foldICmpXNegX ( ICmpInst &  I )

static

Definition at line 4067 of file InstCombineCompares.cpp.

References llvm::CmpInst::Create(), llvm::Constant::getNullValue(), llvm::ICmpInst::getSignedPredicate(), llvm::CmpInst::getSwappedPredicate(), I, llvm::CmpInst::isSigned(), llvm::CmpInst::isUnsigned(), llvm::PatternMatch::m_c_ICmp(), llvm::PatternMatch::m_Deferred(), llvm::PatternMatch::m_NSWNeg(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), and X.

Referenced by llvm::InstCombinerImpl::foldICmpBinOp().

foldReductionIdiom()

static Instruction * foldReductionIdiom ( ICmpInst &  I, InstCombiner::BuilderTy &  Builder, const DataLayout &  DL  )

static

This function folds patterns produced by lowering of reduce idioms, such as llvm.vector.reduce.and which are lowered into instruction chains.

This code attempts to generate fewer number of scalar comparisons instead of vector comparisons when possible.

vec_ne = icmp ne <8 x i8> lhs, rhs scalar_ne = bitcast <8 x i1> vec_ne to i8 res = icmp <pred> i8 scalar_ne, 0

into

lhs.scalar = bitcast <8 x i8> lhs to i64 rhs.scalar = bitcast <8 x i8> rhs to i64 res = icmp <pred> i64 lhs.scalar, rhs.scalar

for <pred> in {ne, eq}.

Definition at line 6277 of file InstCombineCompares.cpp.

References Builder, llvm::CmpInst::Create(), DL, llvm::Value::getName(), llvm::Value::getType(), I, llvm::CmpInst::ICMP_NE, llvm::ICmpInst::isEquality(), LHS, llvm::PatternMatch::m_BitCast(), llvm::PatternMatch::m_ICmp(), llvm::PatternMatch::m_OneUse(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::m_Zero(), llvm::PatternMatch::match(), and RHS.

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

foldShiftIntoShiftInAnotherHandOfAndInICmp()

static Value * foldShiftIntoShiftInAnotherHandOfAndInICmp ( ICmpInst &  I, const SimplifyQuery  SQ, InstCombiner::BuilderTy &  Builder  )

static

Definition at line 3828 of file InstCombineCompares.cpp.

References assert(), Builder, llvm::CallingConv::C, llvm::computeKnownBits(), llvm::KnownBits::countMinLeadingZeros(), llvm::APInt::getAllOnes(), llvm::KnownBits::getBitWidth(), llvm::Constant::getNullValue(), llvm::Instruction::getOpcode(), llvm::User::getOperand(), llvm::Type::getScalarSizeInBits(), llvm::Value::getType(), llvm::Constant::getUniqueInteger(), llvm::SimplifyQuery::getWithInstruction(), llvm::ConstantExpr::getZExtOrBitCast(), llvm::Value::hasOneUse(), I, llvm::CmpInst::ICMP_ULT, llvm::Constant::isNullValue(), llvm::Type::isVectorTy(), llvm::PatternMatch::m_BinOp(), llvm::PatternMatch::m_c_And(), llvm::PatternMatch::m_CombineAnd(), llvm::PatternMatch::m_Instruction(), llvm::PatternMatch::m_LogicalShift(), llvm::PatternMatch::m_LShr(), llvm::PatternMatch::m_OneUse(), llvm::PatternMatch::m_SpecificInt_ICMP(), llvm::PatternMatch::m_TruncOrSelf(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::m_Zero(), llvm::PatternMatch::m_ZExtOrSelf(), llvm::PatternMatch::match(), llvm::simplifyAddInst(), std::swap(), T1, llvm::APInt::ule(), llvm::APInt::ult(), X, and Y.

Referenced by llvm::InstCombinerImpl::foldICmpBinOp().

foldVectorCmp()

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

static

Definition at line 6158 of file InstCombineCompares.cpp.

References Builder, llvm::CallingConv::C, llvm::CallInst::Create(), F, llvm::Intrinsic::getDeclaration(), llvm::ConstantVector::getSplat(), llvm::Value::getType(), llvm::Value::hasOneUse(), I, llvm::isSplatValue(), LHS, llvm::PatternMatch::m_Constant(), llvm::PatternMatch::m_OneUse(), llvm::PatternMatch::m_Shuffle(), llvm::PatternMatch::m_Undef(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::m_VecReverse(), llvm::PatternMatch::match(), RHS, X, and Y.

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

getAsConstantIndexedAddress()

static std::pair< Value *, Value * > getAsConstantIndexedAddress ( Type *  ElemTy, 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 649 of file InstCombineCompares.cpp.

References DL, GEP, llvm::IntegerType::get(), llvm::ConstantExpr::getAdd(), llvm::Constant::getNullValue(), and llvm::ConstantExpr::getSExtOrTrunc().

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 5423 of file InstCombineCompares.cpp.

References llvm::BitWidth, llvm::APInt::getAllOnes(), llvm::APInt::getBitsSetFrom(), llvm::APInt::getSignMask(), I, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULT, llvm::InstCombiner::isSignBitCheck(), llvm::PatternMatch::m_APInt(), llvm::PatternMatch::match(), and RHS.

Referenced by llvm::InstCombinerImpl::foldICmpUsingKnownBits().

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 67 of file InstCombineCompares.cpp.

References I.

Referenced by llvm::InstCombinerImpl::foldICmpWithDominatingICmp().

isChainSelectCmpBranch()

static bool isChainSelectCmpBranch ( const SelectInst *  SI )

static

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

Definition at line 5515 of file InstCombineCompares.cpp.

References llvm::BasicBlock::getTerminator(), and SI.

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

isNeutralValue()

static bool isNeutralValue ( Instruction::BinaryOps  BinaryOp, Value *  RHS, bool  IsSigned  )

static

Definition at line 5105 of file InstCombineCompares.cpp.

References llvm::Value::getType(), llvm::Type::isIntOrIntVectorTy(), llvm_unreachable, llvm::PatternMatch::m_One(), llvm::PatternMatch::m_Zero(), llvm::PatternMatch::match(), and RHS.

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 78 of file InstCombineCompares.cpp.

References llvm::CallingConv::C, and llvm::ICmpInst::isRelational().

Referenced by llvm::InstCombinerImpl::foldICmpMulConstant(), and llvm::InstCombinerImpl::foldICmpShlConstant().

processUGT_ADDCST_ADD()

static Instruction * processUGT_ADDCST_ADD ( ICmpInst &  I, Value *  A, Value *  B, ConstantInt *  CI2, ConstantInt *  CI1, InstCombinerImpl &  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 1100 of file InstCombineCompares.cpp.

References A, llvm::Add, B, llvm::InstCombiner::Builder, Builder, llvm::InstCombiner::ComputeMaxSignificantBits(), llvm::APInt::countr_zero(), llvm::ExtractValueInst::Create(), llvm::InstCombinerImpl::eraseInstFromFunction(), F, llvm::IntegerType::get(), llvm::ConstantInt::getBitWidth(), llvm::Value::getContext(), llvm::Intrinsic::getDeclaration(), llvm::APInt::getLowBitsSet(), llvm::User::getOperand(), llvm::Type::getPrimitiveSizeInBits(), llvm::Value::getType(), llvm::ConstantInt::getValue(), llvm::Value::hasOneUse(), I, llvm::APInt::isPowerOf2(), llvm::InstCombiner::replaceInstUsesWith(), and llvm::Value::users().

Referenced by llvm::InstCombinerImpl::foldICmpWithConstant().

processUMulZExtIdiom()

static Instruction * processUMulZExtIdiom ( ICmpInst &  I, Value *  MulVal, Value *  OtherVal, InstCombinerImpl &  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 5206 of file InstCombineCompares.cpp.

References A, llvm::InstCombiner::addToWorklist(), assert(), B, llvm::InstCombiner::Builder, Builder, llvm::APInt::countl_zero(), llvm::ExtractValueInst::Create(), llvm::BinaryOperator::CreateNot(), llvm::APInt::eq(), F, llvm::APInt::getBitWidth(), llvm::ConstantInt::getBitWidth(), llvm::Intrinsic::getDeclaration(), llvm::APInt::getMaxValue(), llvm::APInt::getOneBitSet(), llvm::Type::getPrimitiveSizeInBits(), llvm::Value::getType(), llvm::ConstantInt::getValue(), llvm::Value::hasNUsesOrMore(), I, 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(), LHS, llvm_unreachable, llvm::APInt::logBase2(), llvm::PatternMatch::m_And(), llvm::PatternMatch::m_ConstantInt(), llvm::PatternMatch::m_Value(), llvm::make_early_inc_range(), llvm::PatternMatch::match(), llvm::Mul, llvm::InstCombiner::replaceInstUsesWith(), RHS, llvm::User::setOperand(), llvm::APInt::trunc(), llvm::Value::users(), and llvm::APInt::zext().

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

rewriteGEPAsOffset()

static Value * rewriteGEPAsOffset ( Type *  ElemTy, 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 535 of file InstCombineCompares.cpp.

References llvm::PHINode::addIncoming(), llvm::sampleprof::Base, Builder, llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::contains(), llvm::PHINode::Create(), DL, E, GEP, llvm::IntegerType::get(), llvm::Constant::getNullValue(), llvm::Type::getPointerTo(), llvm::Value::getType(), I, isZero(), llvm_unreachable, PHI, and setInsertionPoint().

Referenced by transformToIndexedCompare().

setInsertionPoint()

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

static

Definition at line 510 of file InstCombineCompares.cpp.

References A, assert(), Builder, I, and PHI.

Referenced by rewriteGEPAsOffset().

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 54 of file InstCombineCompares.cpp.

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

Referenced by llvm::InstCombinerImpl::foldICmpDivConstant(), and llvm::InstCombinerImpl::foldICmpSubConstant().

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. TODO: Shouldn't this be part of CGP instead?

Returns

true if Op0 and Op1 should be swapped.

Definition at line 5461 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::InstCombinerImpl::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 690 of file InstCombineCompares.cpp.

References canRewriteGEPAsOffset(), Cond, DL, getAsConstantIndexedAddress(), llvm::ICmpInst::getSignedPredicate(), llvm::GEPOperator::getSourceElementType(), llvm::Value::getType(), llvm::GEPOperator::hasAllConstantIndices(), llvm::Type::isVectorTy(), rewriteGEPAsOffset(), and RHS.

Referenced by llvm::InstCombinerImpl::foldGEPICmp().