LLVM  mainline
Defines | Enumerations | Functions
InstCombineAndOrXor.cpp File Reference
#include "InstCombineInternal.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Transforms/Utils/CmpInstAnalysis.h"
Include dependency graph for InstCombineAndOrXor.cpp:

Go to the source code of this file.

Defines

#define DEBUG_TYPE   "instcombine"

Enumerations

enum  MaskedICmpType {
  FoldMskICmp_AMask_AllOnes = 1, FoldMskICmp_AMask_NotAllOnes = 2, FoldMskICmp_BMask_AllOnes = 4, FoldMskICmp_BMask_NotAllOnes = 8,
  FoldMskICmp_Mask_AllZeroes = 16, FoldMskICmp_Mask_NotAllZeroes = 32, FoldMskICmp_AMask_Mixed = 64, FoldMskICmp_AMask_NotMixed = 128,
  FoldMskICmp_BMask_Mixed = 256, FoldMskICmp_BMask_NotMixed = 512
}
 enum for classifying (icmp eq (A & B), C) and (icmp ne (A & B), C) One of A and B is considered the mask, the other the value. More...

Functions

static Valuedyn_castNotVal (Value *V)
static unsigned getFCmpCode (FCmpInst::Predicate CC, bool &isOrdered)
 getFCmpCode - Similar to getICmpCode but for FCmpInst.
static ValuegetNewICmpValue (bool Sign, unsigned Code, Value *LHS, Value *RHS, InstCombiner::BuilderTy *Builder)
 getNewICmpValue - This is the complement of getICmpCode, which turns an opcode and two operands into either a constant true or false, or a brand new ICmp instruction.
static ValuegetFCmpValue (bool isordered, unsigned code, Value *LHS, Value *RHS, InstCombiner::BuilderTy *Builder)
 getFCmpValue - This is the complement of getFCmpCode, which turns an opcode and two operands into either a FCmp instruction.
static bool isRunOfOnes (ConstantInt *Val, uint32_t &MB, uint32_t &ME)
static unsigned getTypeOfMaskedICmp (Value *A, Value *B, Value *C, ICmpInst::Predicate SCC)
 return the set of pattern classes (from MaskedICmpType) that (icmp SCC (A & B), C) satisfies
static unsigned conjugateICmpMask (unsigned Mask)
 Convert an analysis of a masked ICmp into its equivalent if all boolean operations had the opposite sense.
static bool decomposeBitTestICmp (const ICmpInst *I, ICmpInst::Predicate &Pred, Value *&X, Value *&Y, Value *&Z)
 decomposeBitTestICmp - Decompose an icmp into the form ((X & Y) pred Z) if possible.
static unsigned foldLogOpOfMaskedICmpsHelper (Value *&A, Value *&B, Value *&C, Value *&D, Value *&E, ICmpInst *LHS, ICmpInst *RHS, ICmpInst::Predicate &LHSCC, ICmpInst::Predicate &RHSCC)
 foldLogOpOfMaskedICmpsHelper: handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) return the set of pattern classes (from MaskedICmpType) that both LHS and RHS satisfy
static ValuefoldLogOpOfMaskedICmps (ICmpInst *LHS, ICmpInst *RHS, bool IsAnd, llvm::InstCombiner::BuilderTy *Builder)
 foldLogOpOfMaskedICmps: try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) into a single (icmp(A & X) ==/!= Y)
static bool CollectBSwapParts (Value *V, int OverallLeftShift, uint32_t ByteMask, SmallVectorImpl< Value * > &ByteValues)
 CollectBSwapParts - Analyze the specified subexpression and see if it is capable of providing pieces of a bswap.
static InstructionMatchSelectFromAndOr (Value *A, Value *B, Value *C, Value *D)
 MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D).

Define Documentation

#define DEBUG_TYPE   "instcombine"

Definition at line 23 of file InstCombineAndOrXor.cpp.


Enumeration Type Documentation

enum for classifying (icmp eq (A & B), C) and (icmp ne (A & B), C) One of A and B is considered the mask, the other the value.

This is described as the "AMask" or "BMask" part of the enum. If the enum contains only "Mask", then both A and B can be considered masks. If A is the mask, then it was proven, that (A & C) == C. This is trivial if C == A, or C == 0. If both A and C are constants, this proof is also easy. For the following explanations we assume that A is the mask. The part "AllOnes" declares, that the comparison is true only if (A & B) == A, or all bits of A are set in B. Example: (icmp eq (A & 3), 3) -> FoldMskICmp_AMask_AllOnes The part "AllZeroes" declares, that the comparison is true only if (A & B) == 0, or all bits of A are cleared in B. Example: (icmp eq (A & 3), 0) -> FoldMskICmp_Mask_AllZeroes The part "Mixed" declares, that (A & B) == C and C might or might not contain any number of one bits and zero bits. Example: (icmp eq (A & 3), 1) -> FoldMskICmp_AMask_Mixed The Part "Not" means, that in above descriptions "==" should be replaced by "!=". Example: (icmp ne (A & 3), 3) -> FoldMskICmp_AMask_NotAllOnes If the mask A contains a single bit, then the following is equivalent: (icmp eq (A & B), A) equals (icmp ne (A & B), 0) (icmp ne (A & B), A) equals (icmp eq (A & B), 0)

Enumerator:
FoldMskICmp_AMask_AllOnes 
FoldMskICmp_AMask_NotAllOnes 
FoldMskICmp_BMask_AllOnes 
FoldMskICmp_BMask_NotAllOnes 
FoldMskICmp_Mask_AllZeroes 
FoldMskICmp_Mask_NotAllZeroes 
FoldMskICmp_AMask_Mixed 
FoldMskICmp_AMask_NotMixed 
FoldMskICmp_BMask_Mixed 
FoldMskICmp_BMask_NotMixed 

Definition at line 438 of file InstCombineAndOrXor.cpp.


Function Documentation

static bool CollectBSwapParts ( Value V,
int  OverallLeftShift,
uint32_t  ByteMask,
SmallVectorImpl< Value * > &  ByteValues 
) [static]

CollectBSwapParts - Analyze the specified subexpression and see if it is capable of providing pieces of a bswap.

The subexpression provides pieces of a bswap if it is proven that each of the non-zero bytes in the output of the expression came from the corresponding "byte swapped" byte in some other value. For example, if the current subexpression is "(shl i32 %X, 24)" then we know that the expression deposits the low byte of X into the high byte of the bswap result and that all other bytes are zero. This expression is accepted, the high byte of ByteValues is set to X to indicate a correct match.

This function returns true if the match was unsuccessful and false if so. On entry to the function the "OverallLeftShift" is a signed integer value indicating the number of bytes that the subexpression is later shifted. For example, if the expression is later right shifted by 16 bits, the OverallLeftShift value would be -2 on entry. This is used to specify which byte of ByteValues is actually being set.

Similarly, ByteMask is a bitmask where a bit is clear if its corresponding byte is masked to zero by a user. For example, in (X & 255), X will be processed with a bytemask of 1. Because bytemask is 32-bits, this limits this function to working on up to 32-byte (256 bit) values. ByteMask is always in the local (OverallLeftShift) coordinate space.

Definition at line 1534 of file InstCombineAndOrXor.cpp.

References llvm::APIntOps::And(), llvm::countTrailingZeros(), llvm::Instruction::getOpcode(), llvm::User::getOperand(), llvm::Type::getPrimitiveSizeInBits(), llvm::Value::getType(), llvm::Instruction::isLogicalShift(), llvm::isPowerOf2_32(), llvm::APIntOps::Or(), and llvm::SmallVectorTemplateCommon< T, typename >::size().

static unsigned conjugateICmpMask ( unsigned  Mask) [static]

Convert an analysis of a masked ICmp into its equivalent if all boolean operations had the opposite sense.

Since each "NotXXX" flag (recording !=) is adjacent to the corresponding normal flag (recording ==), this just involves swapping those bits over.

Definition at line 524 of file InstCombineAndOrXor.cpp.

References FoldMskICmp_AMask_AllOnes, FoldMskICmp_AMask_Mixed, FoldMskICmp_AMask_NotAllOnes, FoldMskICmp_AMask_NotMixed, FoldMskICmp_BMask_AllOnes, FoldMskICmp_BMask_Mixed, FoldMskICmp_BMask_NotAllOnes, FoldMskICmp_BMask_NotMixed, FoldMskICmp_Mask_AllZeroes, and FoldMskICmp_Mask_NotAllZeroes.

Referenced by foldLogOpOfMaskedICmps().

static bool decomposeBitTestICmp ( const ICmpInst I,
ICmpInst::Predicate &  Pred,
Value *&  X,
Value *&  Y,
Value *&  Z 
) [static]
static Value* dyn_castNotVal ( Value V) [inline, static]
static Value* foldLogOpOfMaskedICmps ( ICmpInst LHS,
ICmpInst RHS,
bool  IsAnd,
llvm::InstCombiner::BuilderTy Builder 
) [static]
static unsigned foldLogOpOfMaskedICmpsHelper ( Value *&  A,
Value *&  B,
Value *&  C,
Value *&  D,
Value *&  E,
ICmpInst LHS,
ICmpInst RHS,
ICmpInst::Predicate &  LHSCC,
ICmpInst::Predicate &  RHSCC 
) [static]

foldLogOpOfMaskedICmpsHelper: handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) return the set of pattern classes (from MaskedICmpType) that both LHS and RHS satisfy

Definition at line 591 of file InstCombineAndOrXor.cpp.

References decomposeBitTestICmp(), llvm::Constant::getAllOnesValue(), llvm::User::getOperand(), llvm::Value::getType(), getTypeOfMaskedICmp(), llvm::ICmpInst::isEquality(), llvm::Type::isIntegerTy(), llvm::Type::isVectorTy(), llvm::PatternMatch::m_And(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::R11, llvm::R12, and R2.

Referenced by foldLogOpOfMaskedICmps().

static unsigned getFCmpCode ( FCmpInst::Predicate  CC,
bool isOrdered 
) [static]
static Value* getFCmpValue ( bool  isordered,
unsigned  code,
Value LHS,
Value RHS,
InstCombiner::BuilderTy Builder 
) [static]
static Value* getNewICmpValue ( bool  Sign,
unsigned  Code,
Value LHS,
Value RHS,
InstCombiner::BuilderTy Builder 
) [static]

getNewICmpValue - This is the complement of getICmpCode, which turns an opcode and two operands into either a constant true or false, or a brand new ICmp instruction.

The sign is passed in to determine which kind of predicate to use in the new icmp instruction.

Definition at line 71 of file InstCombineAndOrXor.cpp.

References llvm::IRBuilder< preserveNames, T, Inserter >::CreateICmp(), and llvm::getICmpValue().

Referenced by llvm::InstCombiner::FoldAndOfICmps(), llvm::InstCombiner::FoldOrOfICmps(), and llvm::InstCombiner::visitXor().

static unsigned getTypeOfMaskedICmp ( Value A,
Value B,
Value C,
ICmpInst::Predicate  SCC 
) [static]
static bool isRunOfOnes ( ConstantInt Val,
uint32_t &  MB,
uint32_t &  ME 
) [static]
static Instruction* MatchSelectFromAndOr ( Value A,
Value B,
Value C,
Value D 
) [static]

MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D).

Check If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then we can simplify this expression to "cond ? C : D or B".

Definition at line 1668 of file InstCombineAndOrXor.cpp.

References llvm::SelectInst::Create(), llvm::Value::getType(), llvm::Type::isIntegerTy(), llvm::PatternMatch::m_Not(), llvm::PatternMatch::m_SExt(), llvm::PatternMatch::m_Specific(), llvm::PatternMatch::m_Value(), and llvm::PatternMatch::match().

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