InstCombineShifts.cpp File Reference

#include "InstCombineInternal.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Transforms/InstCombine/InstCombiner.h"

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "instcombine"

Functions
bool	canTryToConstantAddTwoShiftAmounts (Value *Sh0, Value *ShAmt0, Value *Sh1, Value *ShAmt1)
static Instruction *	dropRedundantMaskingOfLeftShiftInput (BinaryOperator *OuterShift, const SimplifyQuery &Q, InstCombiner::BuilderTy &Builder)
static Instruction *	foldShiftOfShiftedBinOp (BinaryOperator &I, InstCombiner::BuilderTy &Builder)
	If we have a shift-by-constant of a bin op (bitwise logic op or add/sub w/ shl) that itself has a shift-by-constant operand with identical opcode, we may be able to convert that into 2 independent shifts followed by the logic op.
static bool	canEvaluateShiftedShift (unsigned OuterShAmt, bool IsOuterShl, ShiftSemantics Semantics, Instruction *InnerShift, InstCombinerImpl &IC, Instruction *CxtI)
	Return true if we can simplify two logical (either left or right) shifts that have constant shift amounts: OuterShift (InnerShift X, C1), C2.
static Value *	foldShiftedShift (BinaryOperator *InnerShift, unsigned OuterShAmt, bool IsOuterShl, ShiftSemantics Semantics, InstCombiner::BuilderTy &Builder)
	Fold OuterShift (InnerShift X, C1), C2.
static bool	canShiftBinOpWithConstantRHS (BinaryOperator &Shift, BinaryOperator *BO)
static bool	setShiftFlags (BinaryOperator &I, const SimplifyQuery &Q)

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "instcombine"

Definition at line 21 of file InstCombineShifts.cpp.

Function Documentation

canEvaluateShiftedShift()

bool canEvaluateShiftedShift ( unsigned OuterShAmt, bool IsOuterShl, ShiftSemantics Semantics, Instruction * InnerShift, InstCombinerImpl & IC, Instruction * CxtI )

static

Return true if we can simplify two logical (either left or right) shifts that have constant shift amounts: OuterShift (InnerShift X, C1), C2.

Definition at line 575 of file InstCombineShifts.cpp.

References assert(), llvm::cast(), llvm::APInt::getLowBitsSet(), llvm::Instruction::getOpcode(), llvm::User::getOperand(), llvm::Type::getScalarSizeInBits(), llvm::Value::getType(), llvm::APInt::getZExtValue(), llvm::Instruction::isLogicalShift(), llvm::Lossy, llvm::PatternMatch::m_APInt(), llvm::InstCombiner::MaskedValueIsZero(), MaskShift(), llvm::PatternMatch::match(), llvm::Signed, llvm::APInt::ugt(), and llvm::APInt::ult().

canShiftBinOpWithConstantRHS()

bool canShiftBinOpWithConstantRHS ( BinaryOperator & Shift, BinaryOperator * BO )

static

Definition at line 871 of file InstCombineShifts.cpp.

References llvm::BinaryOperator::getOpcode(), llvm::Instruction::isLogicalShift(), llvm::MIPatternMatch::m_Not(), llvm::PatternMatch::m_Value(), and llvm::PatternMatch::match().

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

canTryToConstantAddTwoShiftAmounts()

bool canTryToConstantAddTwoShiftAmounts	(	Value *	Sh0,
		Value *	ShAmt0,
		Value *	Sh1,
		Value *	ShAmt1 )

Definition at line 23 of file InstCombineShifts.cpp.

References llvm::APInt::getAllOnes(), getScalarSizeInBits(), llvm::Type::getScalarSizeInBits(), llvm::Value::getType(), and llvm::APInt::uge().

Referenced by dropRedundantMaskingOfLeftShiftInput(), and llvm::InstCombinerImpl::reassociateShiftAmtsOfTwoSameDirectionShifts().

dropRedundantMaskingOfLeftShiftInput()

Instruction * dropRedundantMaskingOfLeftShiftInput ( BinaryOperator * OuterShift, const SimplifyQuery & Q, InstCombiner::BuilderTy & Builder )

static

Definition at line 189 of file InstCombineShifts.cpp.

References assert(), canTryToConstantAddTwoShiftAmounts(), llvm::ConstantFoldBinaryOpOperands(), llvm::ConstantFoldCastOperand(), llvm::BinaryOperator::Create(), llvm::SimplifyQuery::DL, llvm::dyn_cast_or_null(), llvm::Constant::getAllOnesValue(), llvm::Type::getExtendedType(), llvm::ConstantExpr::getNot(), llvm::BinaryOperator::getOpcode(), llvm::User::getOperand(), llvm::Type::getScalarSizeInBits(), llvm::ConstantInt::getSigned(), llvm::ConstantExpr::getSub(), llvm::ConstantExpr::getTrunc(), llvm::Value::getType(), llvm::Value::hasOneUse(), llvm::PatternMatch::m_Add(), llvm::PatternMatch::m_AllOnes(), llvm::PatternMatch::m_AShr(), llvm::PatternMatch::m_c_And(), llvm::PatternMatchHelpers::m_CombineAnd(), llvm::PatternMatchHelpers::m_CombineOr(), llvm::PatternMatch::m_Deferred(), llvm::PatternMatch::m_LShr(), llvm::MIPatternMatch::m_Not(), llvm::PatternMatch::m_One(), llvm::PatternMatch::m_Shift(), llvm::PatternMatch::m_Shl(), llvm::PatternMatch::m_Shr(), llvm::PatternMatch::m_Trunc(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::m_ZExtOrSelf(), llvm::Masked, llvm::PatternMatch::match(), llvm::IntegerType::MAX_INT_BITS, llvm::Constant::replaceUndefsWith(), llvm::simplifyAddInst(), llvm::simplifySubInst(), and X.

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

foldShiftedShift()

Value * foldShiftedShift ( BinaryOperator * InnerShift, unsigned OuterShAmt, bool IsOuterShl, ShiftSemantics Semantics, InstCombiner::BuilderTy & Builder )

static

Fold OuterShift (InnerShift X, C1), C2.

See canEvaluateShiftedShift() for the constraints on these instructions.

Definition at line 724 of file InstCombineShifts.cpp.

References assert(), llvm::dyn_cast(), llvm::APInt::getHighBitsSet(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::APInt::getLowBitsSet(), llvm::Constant::getNullValue(), llvm::BinaryOperator::getOpcode(), llvm::User::getOperand(), llvm::Type::getScalarSizeInBits(), llvm::Value::getType(), llvm::APInt::getZExtValue(), llvm::Instruction::hasNoSignedWrap(), llvm::Instruction::hasNoUnsignedWrap(), llvm::PatternMatch::m_APInt(), llvm::PatternMatch::match(), llvm::Instruction::setHasNoSignedWrap(), llvm::Instruction::setHasNoUnsignedWrap(), llvm::Instruction::setIsExact(), llvm::User::setOperand(), llvm::Signed, and llvm::Unsigned.

foldShiftOfShiftedBinOp()

Instruction * foldShiftOfShiftedBinOp ( BinaryOperator & I, InstCombiner::BuilderTy & Builder )

static

If we have a shift-by-constant of a bin op (bitwise logic op or add/sub w/ shl) that itself has a shift-by-constant operand with identical opcode, we may be able to convert that into 2 independent shifts followed by the logic op.

This eliminates a use of an intermediate value (reduces dependency chain).

Definition at line 353 of file InstCombineShifts.cpp.

References assert(), llvm::BinaryOperator::Create(), llvm::dyn_cast(), llvm::ConstantExpr::getAdd(), I, llvm::CmpInst::ICMP_ULT, llvm::PatternMatch::m_BinOp(), llvm::PatternMatch::m_Constant(), llvm::PatternMatch::m_ImmConstant(), llvm::PatternMatch::m_SpecificInt_ICMP(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), Size, X, and Y.

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

setShiftFlags()

bool setShiftFlags ( BinaryOperator & I, const SimplifyQuery & Q )

static

Definition at line 1092 of file InstCombineShifts.cpp.

References llvm::SimplifyQuery::AC, assert(), llvm::BitWidth, Changed, llvm::computeKnownBits(), llvm::ComputeNumSignBits(), llvm::KnownBits::countMinLeadingZeros(), llvm::KnownBits::countMinSignBits(), llvm::KnownBits::countMinTrailingZeros(), llvm::SimplifyQuery::CxtI, llvm::SimplifyQuery::DL, llvm::SimplifyQuery::DT, llvm::KnownBits::getBitWidth(), llvm::APInt::getLimitedValue(), llvm::KnownBits::getMaxValue(), I, llvm::PatternMatch::m_Intrinsic(), llvm::PatternMatch::m_Shl(), llvm::PatternMatch::m_Specific(), llvm::PatternMatch::m_Value(), and llvm::PatternMatch::match().

Referenced by llvm::InstCombinerImpl::visitAShr(), llvm::InstCombinerImpl::visitLShr(), and llvm::InstCombinerImpl::visitShl().