LLVM  mainline
Defines | Functions
InstCombineShifts.cpp File Reference
#include "InstCombineInternal.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
Include dependency graph for InstCombineShifts.cpp:

Go to the source code of this file.

Defines

#define DEBUG_TYPE   "instcombine"

Functions

static bool CanEvaluateShifted (Value *V, unsigned NumBits, bool isLeftShift, InstCombiner &IC, Instruction *CxtI)
 CanEvaluateShifted - See if we can compute the specified value, but shifted logically to the left or right by some number of bits.
static ValueGetShiftedValue (Value *V, unsigned NumBits, bool isLeftShift, InstCombiner &IC, const DataLayout &DL)
 GetShiftedValue - When CanEvaluateShifted returned true for an expression, this value inserts the new computation that produces the shifted value.

Define Documentation

#define DEBUG_TYPE   "instcombine"

Definition at line 22 of file InstCombineShifts.cpp.


Function Documentation

static bool CanEvaluateShifted ( Value V,
unsigned  NumBits,
bool  isLeftShift,
InstCombiner IC,
Instruction CxtI 
) [static]

CanEvaluateShifted - See if we can compute the specified value, but shifted logically to the left or right by some number of bits.

This should return true if the expression can be computed for the same cost as the current expression tree. This is used to eliminate extraneous shifting from things like: C = shl i128 A, 64 D = shl i128 B, 96 E = or i128 C, D F = lshr i128 E, 64 where the client will ask if E can be computed shifted right by 64-bits. If this succeeds, the GetShiftedValue function will be called to produce the value.

Definition at line 70 of file InstCombineShifts.cpp.

References llvm::APIntOps::And(), CanEvaluateTruncated(), llvm::dyn_cast(), llvm::SelectInst::getFalseValue(), llvm::APInt::getHighBitsSet(), llvm::ConstantInt::getLimitedValue(), llvm::APInt::getLowBitsSet(), llvm::Instruction::getOpcode(), llvm::User::getOperand(), llvm::Type::getScalarSizeInBits(), llvm::SelectInst::getTrueValue(), llvm::Value::getType(), llvm::ConstantInt::getValue(), llvm::ConstantInt::getZExtValue(), llvm::Value::hasOneUse(), I, llvm::PHINode::incoming_values(), llvm::LShr, llvm::PatternMatch::m_ConstantInt(), llvm::PatternMatch::m_LShr(), llvm::PatternMatch::m_Shl(), llvm::PatternMatch::m_Value(), llvm::MaskedValueIsZero(), llvm::PatternMatch::match(), llvm::APIntOps::Or(), llvm::TargetOpcode::PHI, llvm::MCID::Select, llvm::SI, llvm::APInt::ult(), and llvm::APIntOps::Xor().

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

static Value* GetShiftedValue ( Value V,
unsigned  NumBits,
bool  isLeftShift,
InstCombiner IC,
const DataLayout DL 
) [static]