InstCombineSimplifyDemanded.cpp File Reference

#include "InstCombineInternal.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Transforms/InstCombine/InstCombiner.h"

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "instcombine"

Functions
static bool	ShrinkDemandedConstant (Instruction *I, unsigned OpNo, const APInt &Demanded)
	Check to see if the specified operand of the specified instruction is a constant integer.
static Value *	simplifyShiftSelectingPackedElement (Instruction *I, const APInt &DemandedMask, InstCombinerImpl &IC, unsigned Depth)
	Let N = 2 * M.
static unsigned	getBitWidth (Type *Ty, const DataLayout &DL)
	Returns the bitwidth of the given scalar or pointer type.
static Constant *	getFPClassConstant (Type *Ty, FPClassTest Mask, bool IsCanonicalizing=false)
	For floating-point classes that resolve to a single bit pattern, return that value.
static Value *	simplifyDemandedFPClassMinMax (KnownFPClass &Known, Intrinsic::ID IID, const CallInst *CI, FPClassTest DemandedMask, KnownFPClass KnownLHS, KnownFPClass KnownRHS, const Function &F, bool NSZ)
static FastMathFlags	inferFastMathValueFlagsBinOp (FastMathFlags FMF, FPClassTest ValidResults, const KnownFPClass &KnownLHS, const KnownFPClass &KnownRHS)
	Try to set an inferred no-nans or no-infs in FMF.

Variables
static cl::opt< bool >	VerifyKnownBits ("instcombine-verify-known-bits", cl::desc("Verify that computeKnownBits() and " "SimplifyDemandedBits() are consistent"), cl::Hidden, cl::init(false))
static cl::opt< unsigned >	SimplifyDemandedVectorEltsDepthLimit ("instcombine-simplify-vector-elts-depth", cl::desc("Depth limit when simplifying vector instructions and their operands"), cl::Hidden, cl::init(10))

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "instcombine"

Definition at line 26 of file InstCombineSimplifyDemanded.cpp.

Function Documentation

getBitWidth()

unsigned getBitWidth ( Type * Ty, const DataLayout & DL )

static

Returns the bitwidth of the given scalar or pointer type.

For vector types, returns the element type's bitwidth.

Definition at line 123 of file InstCombineSimplifyDemanded.cpp.

References llvm::BitWidth, and DL.

getFPClassConstant()

Constant * getFPClassConstant ( Type * Ty, FPClassTest Mask, bool IsCanonicalizing = false )

static

For floating-point classes that resolve to a single bit pattern, return that value.

Definition at line 2008 of file InstCombineSimplifyDemanded.cpp.

References llvm::fcNan, llvm::fcNegInf, llvm::fcNegZero, llvm::fcNone, llvm::fcPosInf, llvm::fcPosZero, llvm::PoisonValue::get(), llvm::ConstantFP::getInfinity(), llvm::Constant::getNullValue(), llvm::ConstantFP::getQNaN(), and llvm::ConstantFP::getZero().

Referenced by llvm::InstCombinerImpl::SimplifyDemandedFPClass(), simplifyDemandedFPClassMinMax(), llvm::InstCombinerImpl::SimplifyDemandedUseFPClass(), and llvm::InstCombinerImpl::SimplifyMultipleUseDemandedFPClass().

inferFastMathValueFlagsBinOp()

FastMathFlags inferFastMathValueFlagsBinOp ( FastMathFlags FMF, FPClassTest ValidResults, const KnownFPClass & KnownLHS, const KnownFPClass & KnownRHS )

static

Try to set an inferred no-nans or no-infs in FMF.

ValidResults is a mask of known valid results for the operator (already computed from the result, and the known operand inputs, KnownLHS and KnownRHS)

Definition at line 2136 of file InstCombineSimplifyDemanded.cpp.

References llvm::fcInf, llvm::fcNan, llvm::fcNone, llvm::KnownFPClass::isKnownNeverInfinity(), llvm::KnownFPClass::isKnownNeverNaN(), llvm::FastMathFlags::noInfs(), llvm::FastMathFlags::noNaNs(), llvm::FastMathFlags::setNoInfs(), and llvm::FastMathFlags::setNoNaNs().

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

ShrinkDemandedConstant()

bool ShrinkDemandedConstant ( Instruction * I, unsigned OpNo, const APInt & Demanded )

static

Check to see if the specified operand of the specified instruction is a constant integer.

If so, check to see if there are any bits set in the constant that are not demanded. If so, shrink the constant and return true.

Definition at line 43 of file InstCombineSimplifyDemanded.cpp.

References assert(), llvm::CallingConv::C, I, llvm::PatternMatch::m_APInt(), and llvm::PatternMatch::match().

Referenced by llvm::TargetLowering::ShrinkDemandedConstant(), llvm::TargetLowering::SimplifyDemandedBits(), and llvm::InstCombinerImpl::SimplifyDemandedUseBits().

simplifyDemandedFPClassMinMax()

Value * simplifyDemandedFPClassMinMax ( KnownFPClass & Known, Intrinsic::ID IID, const CallInst * CI, FPClassTest DemandedMask, KnownFPClass KnownLHS, KnownFPClass KnownRHS, const Function & F, bool NSZ )

static

Propagate nnan-ness to simplify edge case checks.

Definition at line 2037 of file InstCombineSimplifyDemanded.cpp.

References llvm::cannotOrderStrictlyGreater(), llvm::cannotOrderStrictlyLess(), F, llvm::fcNan, llvm::fcNone, llvm::CallBase::getArgOperand(), llvm::Type::getFltSemantics(), getFPClassConstant(), llvm::Type::getScalarType(), llvm::Value::getType(), llvm::KnownFPClass::isKnownNever(), llvm::KnownFPClass::KnownFPClasses, llvm::KnownFPClass::knownNot(), llvm_unreachable, llvm::KnownFPClass::maximum, llvm::KnownFPClass::maximumnum, llvm::KnownFPClass::minimum, llvm::KnownFPClass::minimumnum, llvm::KnownFPClass::minMaxLike(), and Mode.

Referenced by llvm::InstCombinerImpl::SimplifyDemandedUseFPClass(), and llvm::InstCombinerImpl::SimplifyMultipleUseDemandedFPClass().

simplifyShiftSelectingPackedElement()

Value * simplifyShiftSelectingPackedElement ( Instruction * I, const APInt & DemandedMask, InstCombinerImpl & IC, unsigned Depth )

static

Let N = 2 * M.

Given an N-bit integer representing a pack of two M-bit integers, we can select one of the packed integers by right-shifting by either zero or M (which is the most straightforward to check if M is a power of 2), and then isolating the lower M bits. In this case, we can represent the shift as a select on whether the shr amount is nonzero.

Definition at line 70 of file InstCombineSimplifyDemanded.cpp.

References assert(), llvm::InstCombiner::Builder, llvm::InstCombiner::computeKnownBits(), llvm::IRBuilderBase::CreateICmpEQ(), llvm::IRBuilderBase::CreateSelectWithUnknownProfile(), DEBUG_TYPE, llvm::Depth, llvm::APInt::getActiveBits(), llvm::KnownBits::getMaxValue(), llvm::Value::getName(), llvm::Constant::getNullValue(), llvm::Value::getType(), I, llvm::APInt::isIntN(), llvm::isPowerOf2_64(), llvm::Lower, llvm::PatternMatch::m_c_DisjointOr(), llvm::PatternMatch::m_ConstantInt(), llvm::MIPatternMatch::m_OneUse(), llvm::PatternMatch::m_Shl(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), Select, llvm::IRBuilderBase::SetInsertPoint(), llvm::Upper, and llvm::KnownBits::Zero.

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

Variable Documentation

SimplifyDemandedVectorEltsDepthLimit

cl::opt< unsigned > SimplifyDemandedVectorEltsDepthLimit("instcombine-simplify-vector-elts-depth", cl::desc( "Depth limit when simplifying vector instructions and their operands"), cl::Hidden, cl::init(10)) ( "instcombine-simplify-vector-elts-depth" , cl::desc( "Depth limit when simplifying vector instructions and their operands") , cl::Hidden , cl::init(10)  )

static

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

VerifyKnownBits

cl::opt< bool > VerifyKnownBits("instcombine-verify-known-bits", cl::desc("Verify that computeKnownBits() and " "SimplifyDemandedBits() are consistent"), cl::Hidden, cl::init(false)) ( "instcombine-verify-known-bits" , cl::desc("Verify that computeKnownBits() and " "SimplifyDemandedBits() are consistent") , cl::Hidden , cl::init(false)  )

static

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