LLVM  4.0.0
Macros | 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.

Macros

#define DEBUG_TYPE   "instcombine"
 

Functions

static bool canEvaluateShiftedShift (unsigned FirstShiftAmt, bool IsFirstShiftLeft, Instruction *SecondShift, InstCombiner &IC, Instruction *CxtI)
 Return true if we can simplify two logical (either left or right) shifts that have constant shift amounts. More...
 
static bool CanEvaluateShifted (Value *V, unsigned NumBits, bool IsLeftShift, InstCombiner &IC, Instruction *CxtI)
 See if we can compute the specified value, but shifted logically to the left or right by some number of bits. More...
 
static ValueGetShiftedValue (Value *V, unsigned NumBits, bool isLeftShift, InstCombiner &IC, const DataLayout &DL)
 When CanEvaluateShifted returned true for an expression, this value inserts the new computation that produces the shifted value. More...
 
static InstructionfoldShiftByConstOfShiftByConst (BinaryOperator &I, ConstantInt *COp1, InstCombiner::BuilderTy *Builder)
 Try to fold (X << C1) << C2, where the shifts are some combination of shl/ashr/lshr. More...
 

Macro Definition 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

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 124 of file InstCombineShifts.cpp.

References llvm::APIntOps::And(), canEvaluateShiftedShift(), llvm::dyn_cast(), llvm::SelectInst::getFalseValue(), llvm::APInt::getHighBitsSet(), llvm::ConstantInt::getLimitedValue(), llvm::Instruction::getOpcode(), llvm::User::getOperand(), llvm::SelectInst::getTrueValue(), llvm::ConstantInt::getZExtValue(), llvm::Value::hasOneUse(), I, llvm::PHINode::incoming_values(), 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::MCID::Select, SI, and llvm::APIntOps::Xor().

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

static bool canEvaluateShiftedShift ( unsigned  FirstShiftAmt,
bool  IsFirstShiftLeft,
Instruction SecondShift,
InstCombiner IC,
Instruction CxtI 
)
static
static Instruction* foldShiftByConstOfShiftByConst ( BinaryOperator I,
ConstantInt COp1,
InstCombiner::BuilderTy Builder 
)
static
static Value* GetShiftedValue ( Value V,
unsigned  NumBits,
bool  isLeftShift,
InstCombiner IC,
const DataLayout DL 
)
static