//===- InstCombineAndOrXor.cpp --------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the visitAnd, visitOr, and visitXor functions.
//
//===----------------------------------------------------------------------===//
#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"
using namespace llvm;
using namespace PatternMatch;
#define DEBUG_TYPE "instcombine"
static inline Value *dyn_castNotVal(Value *V) {
// If this is not(not(x)) don't return that this is a not: we want the two
// not's to be folded first.
if (BinaryOperator::isNot(V)) {
Value *Operand = BinaryOperator::getNotArgument(V);
if (!IsFreeToInvert(Operand, Operand->hasOneUse()))
return Operand;
}
// Constants can be considered to be not'ed values...
if (ConstantInt *C = dyn_cast<ConstantInt>(V))
return ConstantInt::get(C->getType(), ~C->getValue());
return nullptr;
}
/// Similar to getICmpCode but for FCmpInst. This encodes a fcmp predicate into
/// a three bit mask. It also returns whether it is an ordered predicate by
/// reference.
static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
isOrdered = false;
switch (CC) {
case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000
case FCmpInst::FCMP_UNO: return 0; // 000
case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001
case FCmpInst::FCMP_UGT: return 1; // 001
case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010
case FCmpInst::FCMP_UEQ: return 2; // 010
case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011
case FCmpInst::FCMP_UGE: return 3; // 011
case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100
case FCmpInst::FCMP_ULT: return 4; // 100
case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101
case FCmpInst::FCMP_UNE: return 5; // 101
case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110
case FCmpInst::FCMP_ULE: return 6; // 110
// True -> 7
default:
// Not expecting FCMP_FALSE and FCMP_TRUE;
llvm_unreachable("Unexpected FCmp predicate!");
}
}
/// 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.
static Value *getNewICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
InstCombiner::BuilderTy *Builder) {
ICmpInst::Predicate NewPred;
if (Value *NewConstant = getICmpValue(Sign, Code, LHS, RHS, NewPred))
return NewConstant;
return Builder->CreateICmp(NewPred, LHS, RHS);
}
/// This is the complement of getFCmpCode, which turns an opcode and two
/// operands into either a FCmp instruction. isordered is passed in to determine
/// which kind of predicate to use in the new fcmp instruction.
static Value *getFCmpValue(bool isordered, unsigned code,
Value *LHS, Value *RHS,
InstCombiner::BuilderTy *Builder) {
CmpInst::Predicate Pred;
switch (code) {
default: llvm_unreachable("Illegal FCmp code!");
case 0: Pred = isordered ? FCmpInst::FCMP_ORD : FCmpInst::FCMP_UNO; break;
case 1: Pred = isordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT; break;
case 2: Pred = isordered ? FCmpInst::FCMP_OEQ : FCmpInst::FCMP_UEQ; break;
case 3: Pred = isordered ? FCmpInst::FCMP_OGE : FCmpInst::FCMP_UGE; break;
case 4: Pred = isordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT; break;
case 5: Pred = isordered ? FCmpInst::FCMP_ONE : FCmpInst::FCMP_UNE; break;
case 6: Pred = isordered ? FCmpInst::FCMP_OLE : FCmpInst::FCMP_ULE; break;
case 7:
if (!isordered)
return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
Pred = FCmpInst::FCMP_ORD; break;
}
return Builder->CreateFCmp(Pred, LHS, RHS);
}
/// \brief Transform BITWISE_OP(BSWAP(A),BSWAP(B)) to BSWAP(BITWISE_OP(A, B))
/// \param I Binary operator to transform.
/// \return Pointer to node that must replace the original binary operator, or
/// null pointer if no transformation was made.
Value *InstCombiner::SimplifyBSwap(BinaryOperator &I) {
IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
// Can't do vectors.
if (I.getType()->isVectorTy()) return nullptr;
// Can only do bitwise ops.
unsigned Op = I.getOpcode();
if (Op != Instruction::And && Op != Instruction::Or &&
Op != Instruction::Xor)
return nullptr;
Value *OldLHS = I.getOperand(0);
Value *OldRHS = I.getOperand(1);
ConstantInt *ConstLHS = dyn_cast<ConstantInt>(OldLHS);
ConstantInt *ConstRHS = dyn_cast<ConstantInt>(OldRHS);
IntrinsicInst *IntrLHS = dyn_cast<IntrinsicInst>(OldLHS);
IntrinsicInst *IntrRHS = dyn_cast<IntrinsicInst>(OldRHS);
bool IsBswapLHS = (IntrLHS && IntrLHS->getIntrinsicID() == Intrinsic::bswap);
bool IsBswapRHS = (IntrRHS && IntrRHS->getIntrinsicID() == Intrinsic::bswap);
if (!IsBswapLHS && !IsBswapRHS)
return nullptr;
if (!IsBswapLHS && !ConstLHS)
return nullptr;
if (!IsBswapRHS && !ConstRHS)
return nullptr;
/// OP( BSWAP(x), BSWAP(y) ) -> BSWAP( OP(x, y) )
/// OP( BSWAP(x), CONSTANT ) -> BSWAP( OP(x, BSWAP(CONSTANT) ) )
Value *NewLHS = IsBswapLHS ? IntrLHS->getOperand(0) :
Builder->getInt(ConstLHS->getValue().byteSwap());
Value *NewRHS = IsBswapRHS ? IntrRHS->getOperand(0) :
Builder->getInt(ConstRHS->getValue().byteSwap());
Value *BinOp = nullptr;
if (Op == Instruction::And)
BinOp = Builder->CreateAnd(NewLHS, NewRHS);
else if (Op == Instruction::Or)
BinOp = Builder->CreateOr(NewLHS, NewRHS);
else //if (Op == Instruction::Xor)
BinOp = Builder->CreateXor(NewLHS, NewRHS);
Function *F = Intrinsic::getDeclaration(I.getModule(), Intrinsic::bswap, ITy);
return Builder->CreateCall(F, BinOp);
}
/// This handles expressions of the form ((val OP C1) & C2). Where
/// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
/// guaranteed to be a binary operator.
Instruction *InstCombiner::OptAndOp(Instruction *Op,
ConstantInt *OpRHS,
ConstantInt *AndRHS,
BinaryOperator &TheAnd) {
Value *X = Op->getOperand(0);
Constant *Together = nullptr;
if (!Op->isShift())
Together = ConstantExpr::getAnd(AndRHS, OpRHS);
switch (Op->getOpcode()) {
case Instruction::Xor:
if (Op->hasOneUse()) {
// (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
Value *And = Builder->CreateAnd(X, AndRHS);
And->takeName(Op);
return BinaryOperator::CreateXor(And, Together);
}
break;
case Instruction::Or:
if (Op->hasOneUse()){
if (Together != OpRHS) {
// (X | C1) & C2 --> (X | (C1&C2)) & C2
Value *Or = Builder->CreateOr(X, Together);
Or->takeName(Op);
return BinaryOperator::CreateAnd(Or, AndRHS);
}
ConstantInt *TogetherCI = dyn_cast<ConstantInt>(Together);
if (TogetherCI && !TogetherCI->isZero()){
// (X | C1) & C2 --> (X & (C2^(C1&C2))) | C1
// NOTE: This reduces the number of bits set in the & mask, which
// can expose opportunities for store narrowing.
Together = ConstantExpr::getXor(AndRHS, Together);
Value *And = Builder->CreateAnd(X, Together);
And->takeName(Op);
return BinaryOperator::CreateOr(And, OpRHS);
}
}
break;
case Instruction::Add:
if (Op->hasOneUse()) {
// Adding a one to a single bit bit-field should be turned into an XOR
// of the bit. First thing to check is to see if this AND is with a
// single bit constant.
const APInt &AndRHSV = AndRHS->getValue();
// If there is only one bit set.
if (AndRHSV.isPowerOf2()) {
// Ok, at this point, we know that we are masking the result of the
// ADD down to exactly one bit. If the constant we are adding has
// no bits set below this bit, then we can eliminate the ADD.
const APInt& AddRHS = OpRHS->getValue();
// Check to see if any bits below the one bit set in AndRHSV are set.
if ((AddRHS & (AndRHSV-1)) == 0) {
// If not, the only thing that can effect the output of the AND is
// the bit specified by AndRHSV. If that bit is set, the effect of
// the XOR is to toggle the bit. If it is clear, then the ADD has
// no effect.
if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
TheAnd.setOperand(0, X);
return &TheAnd;
} else {
// Pull the XOR out of the AND.
Value *NewAnd = Builder->CreateAnd(X, AndRHS);
NewAnd->takeName(Op);
return BinaryOperator::CreateXor(NewAnd, AndRHS);
}
}
}
}
break;
case Instruction::Shl: {
// We know that the AND will not produce any of the bits shifted in, so if
// the anded constant includes them, clear them now!
//
uint32_t BitWidth = AndRHS->getType()->getBitWidth();
uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
ConstantInt *CI = Builder->getInt(AndRHS->getValue() & ShlMask);
if (CI->getValue() == ShlMask)
// Masking out bits that the shift already masks.
return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
if (CI != AndRHS) { // Reducing bits set in and.
TheAnd.setOperand(1, CI);
return &TheAnd;
}
break;
}
case Instruction::LShr: {
// We know that the AND will not produce any of the bits shifted in, so if
// the anded constant includes them, clear them now! This only applies to
// unsigned shifts, because a signed shr may bring in set bits!
//
uint32_t BitWidth = AndRHS->getType()->getBitWidth();
uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
ConstantInt *CI = Builder->getInt(AndRHS->getValue() & ShrMask);
if (CI->getValue() == ShrMask)
// Masking out bits that the shift already masks.
return ReplaceInstUsesWith(TheAnd, Op);
if (CI != AndRHS) {
TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
return &TheAnd;
}
break;
}
case Instruction::AShr:
// Signed shr.
// See if this is shifting in some sign extension, then masking it out
// with an and.
if (Op->hasOneUse()) {
uint32_t BitWidth = AndRHS->getType()->getBitWidth();
uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
Constant *C = Builder->getInt(AndRHS->getValue() & ShrMask);
if (C == AndRHS) { // Masking out bits shifted in.
// (Val ashr C1) & C2 -> (Val lshr C1) & C2
// Make the argument unsigned.
Value *ShVal = Op->getOperand(0);
ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName());
return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
}
}
break;
}
return nullptr;
}
/// Emit a computation of: (V >= Lo && V < Hi) if Inside is true, otherwise
/// (V < Lo || V >= Hi). In practice, we emit the more efficient
/// (V-Lo) \<u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
/// whether to treat the V, Lo and HI as signed or not. IB is the location to
/// insert new instructions.
Value *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
bool isSigned, bool Inside) {
assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
"Lo is not <= Hi in range emission code!");
if (Inside) {
if (Lo == Hi) // Trivially false.
return Builder->getFalse();
// V >= Min && V < Hi --> V < Hi
if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
ICmpInst::Predicate pred = (isSigned ?
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
return Builder->CreateICmp(pred, V, Hi);
}
// Emit V-Lo <u Hi-Lo
Constant *NegLo = ConstantExpr::getNeg(Lo);
Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
return Builder->CreateICmpULT(Add, UpperBound);
}
if (Lo == Hi) // Trivially true.
return Builder->getTrue();
// V < Min || V >= Hi -> V > Hi-1
Hi = SubOne(cast<ConstantInt>(Hi));
if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
ICmpInst::Predicate pred = (isSigned ?
ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
return Builder->CreateICmp(pred, V, Hi);
}
// Emit V-Lo >u Hi-1-Lo
// Note that Hi has already had one subtracted from it, above.
ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
return Builder->CreateICmpUGT(Add, LowerBound);
}
/// Returns true iff Val consists of one contiguous run of 1s with any number
/// of 0s on either side. The 1s are allowed to wrap from LSB to MSB,
/// so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
/// not, since all 1s are not contiguous.
static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
const APInt& V = Val->getValue();
uint32_t BitWidth = Val->getType()->getBitWidth();
if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
// look for the first zero bit after the run of ones
MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
// look for the first non-zero bit
ME = V.getActiveBits();
return true;
}
/// This is part of an expression (LHS +/- RHS) & Mask, where isSub determines
/// whether the operator is a sub. If we can fold one of the following xforms:
///
/// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
/// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
/// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
///
/// return (A +/- B).
///
Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
ConstantInt *Mask, bool isSub,
Instruction &I) {
Instruction *LHSI = dyn_cast<Instruction>(LHS);
if (!LHSI || LHSI->getNumOperands() != 2 ||
!isa<ConstantInt>(LHSI->getOperand(1))) return nullptr;
ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
switch (LHSI->getOpcode()) {
default: return nullptr;
case Instruction::And:
if (ConstantExpr::getAnd(N, Mask) == Mask) {
// If the AndRHS is a power of two minus one (0+1+), this is simple.
if ((Mask->getValue().countLeadingZeros() +
Mask->getValue().countPopulation()) ==
Mask->getValue().getBitWidth())
break;
// Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
// part, we don't need any explicit masks to take them out of A. If that
// is all N is, ignore it.
uint32_t MB = 0, ME = 0;
if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
if (MaskedValueIsZero(RHS, Mask, 0, &I))
break;
}
}
return nullptr;
case Instruction::Or:
case Instruction::Xor:
// If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
if ((Mask->getValue().countLeadingZeros() +
Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
&& ConstantExpr::getAnd(N, Mask)->isNullValue())
break;
return nullptr;
}
if (isSub)
return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold");
return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold");
}
/// 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)
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
};
/// Return the set of pattern classes (from MaskedICmpType)
/// that (icmp SCC (A & B), C) satisfies.
static unsigned getTypeOfMaskedICmp(Value* A, Value* B, Value* C,
ICmpInst::Predicate SCC)
{
ConstantInt *ACst = dyn_cast<ConstantInt>(A);
ConstantInt *BCst = dyn_cast<ConstantInt>(B);
ConstantInt *CCst = dyn_cast<ConstantInt>(C);
bool icmp_eq = (SCC == ICmpInst::ICMP_EQ);
bool icmp_abit = (ACst && !ACst->isZero() &&
ACst->getValue().isPowerOf2());
bool icmp_bbit = (BCst && !BCst->isZero() &&
BCst->getValue().isPowerOf2());
unsigned result = 0;
if (CCst && CCst->isZero()) {
// if C is zero, then both A and B qualify as mask
result |= (icmp_eq ? (FoldMskICmp_Mask_AllZeroes |
FoldMskICmp_Mask_AllZeroes |
FoldMskICmp_AMask_Mixed |
FoldMskICmp_BMask_Mixed)
: (FoldMskICmp_Mask_NotAllZeroes |
FoldMskICmp_Mask_NotAllZeroes |
FoldMskICmp_AMask_NotMixed |
FoldMskICmp_BMask_NotMixed));
if (icmp_abit)
result |= (icmp_eq ? (FoldMskICmp_AMask_NotAllOnes |
FoldMskICmp_AMask_NotMixed)
: (FoldMskICmp_AMask_AllOnes |
FoldMskICmp_AMask_Mixed));
if (icmp_bbit)
result |= (icmp_eq ? (FoldMskICmp_BMask_NotAllOnes |
FoldMskICmp_BMask_NotMixed)
: (FoldMskICmp_BMask_AllOnes |
FoldMskICmp_BMask_Mixed));
return result;
}
if (A == C) {
result |= (icmp_eq ? (FoldMskICmp_AMask_AllOnes |
FoldMskICmp_AMask_Mixed)
: (FoldMskICmp_AMask_NotAllOnes |
FoldMskICmp_AMask_NotMixed));
if (icmp_abit)
result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes |
FoldMskICmp_AMask_NotMixed)
: (FoldMskICmp_Mask_AllZeroes |
FoldMskICmp_AMask_Mixed));
} else if (ACst && CCst &&
ConstantExpr::getAnd(ACst, CCst) == CCst) {
result |= (icmp_eq ? FoldMskICmp_AMask_Mixed
: FoldMskICmp_AMask_NotMixed);
}
if (B == C) {
result |= (icmp_eq ? (FoldMskICmp_BMask_AllOnes |
FoldMskICmp_BMask_Mixed)
: (FoldMskICmp_BMask_NotAllOnes |
FoldMskICmp_BMask_NotMixed));
if (icmp_bbit)
result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes |
FoldMskICmp_BMask_NotMixed)
: (FoldMskICmp_Mask_AllZeroes |
FoldMskICmp_BMask_Mixed));
} else if (BCst && CCst &&
ConstantExpr::getAnd(BCst, CCst) == CCst) {
result |= (icmp_eq ? FoldMskICmp_BMask_Mixed
: FoldMskICmp_BMask_NotMixed);
}
return result;
}
/// 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.
static unsigned conjugateICmpMask(unsigned Mask) {
unsigned NewMask;
NewMask = (Mask & (FoldMskICmp_AMask_AllOnes | FoldMskICmp_BMask_AllOnes |
FoldMskICmp_Mask_AllZeroes | FoldMskICmp_AMask_Mixed |
FoldMskICmp_BMask_Mixed))
<< 1;
NewMask |=
(Mask & (FoldMskICmp_AMask_NotAllOnes | FoldMskICmp_BMask_NotAllOnes |
FoldMskICmp_Mask_NotAllZeroes | FoldMskICmp_AMask_NotMixed |
FoldMskICmp_BMask_NotMixed))
>> 1;
return NewMask;
}
/// Decompose an icmp into the form ((X & Y) pred Z) if possible.
/// The returned predicate is either == or !=. Returns false if
/// decomposition fails.
static bool decomposeBitTestICmp(const ICmpInst *I, ICmpInst::Predicate &Pred,
Value *&X, Value *&Y, Value *&Z) {
ConstantInt *C = dyn_cast<ConstantInt>(I->getOperand(1));
if (!C)
return false;
switch (I->getPredicate()) {
default:
return false;
case ICmpInst::ICMP_SLT:
// X < 0 is equivalent to (X & SignBit) != 0.
if (!C->isZero())
return false;
Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
Pred = ICmpInst::ICMP_NE;
break;
case ICmpInst::ICMP_SGT:
// X > -1 is equivalent to (X & SignBit) == 0.
if (!C->isAllOnesValue())
return false;
Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
Pred = ICmpInst::ICMP_EQ;
break;
case ICmpInst::ICMP_ULT:
// X <u 2^n is equivalent to (X & ~(2^n-1)) == 0.
if (!C->getValue().isPowerOf2())
return false;
Y = ConstantInt::get(I->getContext(), -C->getValue());
Pred = ICmpInst::ICMP_EQ;
break;
case ICmpInst::ICMP_UGT:
// X >u 2^n-1 is equivalent to (X & ~(2^n-1)) != 0.
if (!(C->getValue() + 1).isPowerOf2())
return false;
Y = ConstantInt::get(I->getContext(), ~C->getValue());
Pred = ICmpInst::ICMP_NE;
break;
}
X = I->getOperand(0);
Z = ConstantInt::getNullValue(C->getType());
return true;
}
/// Handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
/// Return the set of pattern classes (from MaskedICmpType)
/// that both LHS and RHS satisfy.
static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A,
Value*& B, Value*& C,
Value*& D, Value*& E,
ICmpInst *LHS, ICmpInst *RHS,
ICmpInst::Predicate &LHSCC,
ICmpInst::Predicate &RHSCC) {
if (LHS->getOperand(0)->getType() != RHS->getOperand(0)->getType()) return 0;
// vectors are not (yet?) supported
if (LHS->getOperand(0)->getType()->isVectorTy()) return 0;
// Here comes the tricky part:
// LHS might be of the form L11 & L12 == X, X == L21 & L22,
// and L11 & L12 == L21 & L22. The same goes for RHS.
// Now we must find those components L** and R**, that are equal, so
// that we can extract the parameters A, B, C, D, and E for the canonical
// above.
Value *L1 = LHS->getOperand(0);
Value *L2 = LHS->getOperand(1);
Value *L11,*L12,*L21,*L22;
// Check whether the icmp can be decomposed into a bit test.
if (decomposeBitTestICmp(LHS, LHSCC, L11, L12, L2)) {
L21 = L22 = L1 = nullptr;
} else {
// Look for ANDs in the LHS icmp.
if (!L1->getType()->isIntegerTy()) {
// You can icmp pointers, for example. They really aren't masks.
L11 = L12 = nullptr;
} else if (!match(L1, m_And(m_Value(L11), m_Value(L12)))) {
// Any icmp can be viewed as being trivially masked; if it allows us to
// remove one, it's worth it.
L11 = L1;
L12 = Constant::getAllOnesValue(L1->getType());
}
if (!L2->getType()->isIntegerTy()) {
// You can icmp pointers, for example. They really aren't masks.
L21 = L22 = nullptr;
} else if (!match(L2, m_And(m_Value(L21), m_Value(L22)))) {
L21 = L2;
L22 = Constant::getAllOnesValue(L2->getType());
}
}
// Bail if LHS was a icmp that can't be decomposed into an equality.
if (!ICmpInst::isEquality(LHSCC))
return 0;
Value *R1 = RHS->getOperand(0);
Value *R2 = RHS->getOperand(1);
Value *R11,*R12;
bool ok = false;
if (decomposeBitTestICmp(RHS, RHSCC, R11, R12, R2)) {
if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
A = R11; D = R12;
} else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
A = R12; D = R11;
} else {
return 0;
}
E = R2; R1 = nullptr; ok = true;
} else if (R1->getType()->isIntegerTy()) {
if (!match(R1, m_And(m_Value(R11), m_Value(R12)))) {
// As before, model no mask as a trivial mask if it'll let us do an
// optimization.
R11 = R1;
R12 = Constant::getAllOnesValue(R1->getType());
}
if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
A = R11; D = R12; E = R2; ok = true;
} else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
A = R12; D = R11; E = R2; ok = true;
}
}
// Bail if RHS was a icmp that can't be decomposed into an equality.
if (!ICmpInst::isEquality(RHSCC))
return 0;
// Look for ANDs in on the right side of the RHS icmp.
if (!ok && R2->getType()->isIntegerTy()) {
if (!match(R2, m_And(m_Value(R11), m_Value(R12)))) {
R11 = R2;
R12 = Constant::getAllOnesValue(R2->getType());
}
if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
A = R11; D = R12; E = R1; ok = true;
} else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
A = R12; D = R11; E = R1; ok = true;
} else {
return 0;
}
}
if (!ok)
return 0;
if (L11 == A) {
B = L12; C = L2;
} else if (L12 == A) {
B = L11; C = L2;
} else if (L21 == A) {
B = L22; C = L1;
} else if (L22 == A) {
B = L21; C = L1;
}
unsigned left_type = getTypeOfMaskedICmp(A, B, C, LHSCC);
unsigned right_type = getTypeOfMaskedICmp(A, D, E, RHSCC);
return left_type & right_type;
}
/// Try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
/// into a single (icmp(A & X) ==/!= Y).
static Value *foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS, bool IsAnd,
llvm::InstCombiner::BuilderTy *Builder) {
Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr, *E = nullptr;
ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
unsigned mask = foldLogOpOfMaskedICmpsHelper(A, B, C, D, E, LHS, RHS,
LHSCC, RHSCC);
if (mask == 0) return nullptr;
assert(ICmpInst::isEquality(LHSCC) && ICmpInst::isEquality(RHSCC) &&
"foldLogOpOfMaskedICmpsHelper must return an equality predicate.");
// In full generality:
// (icmp (A & B) Op C) | (icmp (A & D) Op E)
// == ![ (icmp (A & B) !Op C) & (icmp (A & D) !Op E) ]
//
// If the latter can be converted into (icmp (A & X) Op Y) then the former is
// equivalent to (icmp (A & X) !Op Y).
//
// Therefore, we can pretend for the rest of this function that we're dealing
// with the conjunction, provided we flip the sense of any comparisons (both
// input and output).
// In most cases we're going to produce an EQ for the "&&" case.
ICmpInst::Predicate NEWCC = IsAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
if (!IsAnd) {
// Convert the masking analysis into its equivalent with negated
// comparisons.
mask = conjugateICmpMask(mask);
}
if (mask & FoldMskICmp_Mask_AllZeroes) {
// (icmp eq (A & B), 0) & (icmp eq (A & D), 0)
// -> (icmp eq (A & (B|D)), 0)
Value *newOr = Builder->CreateOr(B, D);
Value *newAnd = Builder->CreateAnd(A, newOr);
// we can't use C as zero, because we might actually handle
// (icmp ne (A & B), B) & (icmp ne (A & D), D)
// with B and D, having a single bit set
Value *zero = Constant::getNullValue(A->getType());
return Builder->CreateICmp(NEWCC, newAnd, zero);
}
if (mask & FoldMskICmp_BMask_AllOnes) {
// (icmp eq (A & B), B) & (icmp eq (A & D), D)
// -> (icmp eq (A & (B|D)), (B|D))
Value *newOr = Builder->CreateOr(B, D);
Value *newAnd = Builder->CreateAnd(A, newOr);
return Builder->CreateICmp(NEWCC, newAnd, newOr);
}
if (mask & FoldMskICmp_AMask_AllOnes) {
// (icmp eq (A & B), A) & (icmp eq (A & D), A)
// -> (icmp eq (A & (B&D)), A)
Value *newAnd1 = Builder->CreateAnd(B, D);
Value *newAnd = Builder->CreateAnd(A, newAnd1);
return Builder->CreateICmp(NEWCC, newAnd, A);
}
// Remaining cases assume at least that B and D are constant, and depend on
// their actual values. This isn't strictly, necessary, just a "handle the
// easy cases for now" decision.
ConstantInt *BCst = dyn_cast<ConstantInt>(B);
if (!BCst) return nullptr;
ConstantInt *DCst = dyn_cast<ConstantInt>(D);
if (!DCst) return nullptr;
if (mask & (FoldMskICmp_Mask_NotAllZeroes | FoldMskICmp_BMask_NotAllOnes)) {
// (icmp ne (A & B), 0) & (icmp ne (A & D), 0) and
// (icmp ne (A & B), B) & (icmp ne (A & D), D)
// -> (icmp ne (A & B), 0) or (icmp ne (A & D), 0)
// Only valid if one of the masks is a superset of the other (check "B&D" is
// the same as either B or D).
APInt NewMask = BCst->getValue() & DCst->getValue();
if (NewMask == BCst->getValue())
return LHS;
else if (NewMask == DCst->getValue())
return RHS;
}
if (mask & FoldMskICmp_AMask_NotAllOnes) {
// (icmp ne (A & B), B) & (icmp ne (A & D), D)
// -> (icmp ne (A & B), A) or (icmp ne (A & D), A)
// Only valid if one of the masks is a superset of the other (check "B|D" is
// the same as either B or D).
APInt NewMask = BCst->getValue() | DCst->getValue();
if (NewMask == BCst->getValue())
return LHS;
else if (NewMask == DCst->getValue())
return RHS;
}
if (mask & FoldMskICmp_BMask_Mixed) {
// (icmp eq (A & B), C) & (icmp eq (A & D), E)
// We already know that B & C == C && D & E == E.
// If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of
// C and E, which are shared by both the mask B and the mask D, don't
// contradict, then we can transform to
// -> (icmp eq (A & (B|D)), (C|E))
// Currently, we only handle the case of B, C, D, and E being constant.
// we can't simply use C and E, because we might actually handle
// (icmp ne (A & B), B) & (icmp eq (A & D), D)
// with B and D, having a single bit set
ConstantInt *CCst = dyn_cast<ConstantInt>(C);
if (!CCst) return nullptr;
ConstantInt *ECst = dyn_cast<ConstantInt>(E);
if (!ECst) return nullptr;
if (LHSCC != NEWCC)
CCst = cast<ConstantInt>(ConstantExpr::getXor(BCst, CCst));
if (RHSCC != NEWCC)
ECst = cast<ConstantInt>(ConstantExpr::getXor(DCst, ECst));
// if there is a conflict we should actually return a false for the
// whole construct
if (((BCst->getValue() & DCst->getValue()) &
(CCst->getValue() ^ ECst->getValue())) != 0)
return ConstantInt::get(LHS->getType(), !IsAnd);
Value *newOr1 = Builder->CreateOr(B, D);
Value *newOr2 = ConstantExpr::getOr(CCst, ECst);
Value *newAnd = Builder->CreateAnd(A, newOr1);
return Builder->CreateICmp(NEWCC, newAnd, newOr2);
}
return nullptr;
}
/// Try to fold a signed range checked with lower bound 0 to an unsigned icmp.
/// Example: (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n
/// If \p Inverted is true then the check is for the inverted range, e.g.
/// (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n
Value *InstCombiner::simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1,
bool Inverted) {
// Check the lower range comparison, e.g. x >= 0
// InstCombine already ensured that if there is a constant it's on the RHS.
ConstantInt *RangeStart = dyn_cast<ConstantInt>(Cmp0->getOperand(1));
if (!RangeStart)
return nullptr;
ICmpInst::Predicate Pred0 = (Inverted ? Cmp0->getInversePredicate() :
Cmp0->getPredicate());
// Accept x > -1 or x >= 0 (after potentially inverting the predicate).
if (!((Pred0 == ICmpInst::ICMP_SGT && RangeStart->isMinusOne()) ||
(Pred0 == ICmpInst::ICMP_SGE && RangeStart->isZero())))
return nullptr;
ICmpInst::Predicate Pred1 = (Inverted ? Cmp1->getInversePredicate() :
Cmp1->getPredicate());
Value *Input = Cmp0->getOperand(0);
Value *RangeEnd;
if (Cmp1->getOperand(0) == Input) {
// For the upper range compare we have: icmp x, n
RangeEnd = Cmp1->getOperand(1);
} else if (Cmp1->getOperand(1) == Input) {
// For the upper range compare we have: icmp n, x
RangeEnd = Cmp1->getOperand(0);
Pred1 = ICmpInst::getSwappedPredicate(Pred1);
} else {
return nullptr;
}
// Check the upper range comparison, e.g. x < n
ICmpInst::Predicate NewPred;
switch (Pred1) {
case ICmpInst::ICMP_SLT: NewPred = ICmpInst::ICMP_ULT; break;
case ICmpInst::ICMP_SLE: NewPred = ICmpInst::ICMP_ULE; break;
default: return nullptr;
}
// This simplification is only valid if the upper range is not negative.
bool IsNegative, IsNotNegative;
ComputeSignBit(RangeEnd, IsNotNegative, IsNegative, /*Depth=*/0, Cmp1);
if (!IsNotNegative)
return nullptr;
if (Inverted)
NewPred = ICmpInst::getInversePredicate(NewPred);
return Builder->CreateICmp(NewPred, Input, RangeEnd);
}
/// Fold (icmp)&(icmp) if possible.
Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
// (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
if (PredicatesFoldable(LHSCC, RHSCC)) {
if (LHS->getOperand(0) == RHS->getOperand(1) &&
LHS->getOperand(1) == RHS->getOperand(0))
LHS->swapOperands();
if (LHS->getOperand(0) == RHS->getOperand(0) &&
LHS->getOperand(1) == RHS->getOperand(1)) {
Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
unsigned Code = getICmpCode(LHS) & getICmpCode(RHS);
bool isSigned = LHS->isSigned() || RHS->isSigned();
return getNewICmpValue(isSigned, Code, Op0, Op1, Builder);
}
}
// handle (roughly): (icmp eq (A & B), C) & (icmp eq (A & D), E)
if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, true, Builder))
return V;
// E.g. (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n
if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/false))
return V;
// E.g. (icmp slt x, n) & (icmp sge x, 0) --> icmp ult x, n
if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/false))
return V;
// This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0);
ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1));
ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1));
if (!LHSCst || !RHSCst) return nullptr;
if (LHSCst == RHSCst && LHSCC == RHSCC) {
// (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
// where C is a power of 2
if (LHSCC == ICmpInst::ICMP_ULT &&
LHSCst->getValue().isPowerOf2()) {
Value *NewOr = Builder->CreateOr(Val, Val2);
return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
}
// (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0)
if (LHSCC == ICmpInst::ICMP_EQ && LHSCst->isZero()) {
Value *NewOr = Builder->CreateOr(Val, Val2);
return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
}
}
// (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2
// where CMAX is the all ones value for the truncated type,
// iff the lower bits of C2 and CA are zero.
if (LHSCC == ICmpInst::ICMP_EQ && LHSCC == RHSCC &&
LHS->hasOneUse() && RHS->hasOneUse()) {
Value *V;
ConstantInt *AndCst, *SmallCst = nullptr, *BigCst = nullptr;
// (trunc x) == C1 & (and x, CA) == C2
// (and x, CA) == C2 & (trunc x) == C1
if (match(Val2, m_Trunc(m_Value(V))) &&
match(Val, m_And(m_Specific(V), m_ConstantInt(AndCst)))) {
SmallCst = RHSCst;
BigCst = LHSCst;
} else if (match(Val, m_Trunc(m_Value(V))) &&
match(Val2, m_And(m_Specific(V), m_ConstantInt(AndCst)))) {
SmallCst = LHSCst;
BigCst = RHSCst;
}
if (SmallCst && BigCst) {
unsigned BigBitSize = BigCst->getType()->getBitWidth();
unsigned SmallBitSize = SmallCst->getType()->getBitWidth();
// Check that the low bits are zero.
APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize);
if ((Low & AndCst->getValue()) == 0 && (Low & BigCst->getValue()) == 0) {
Value *NewAnd = Builder->CreateAnd(V, Low | AndCst->getValue());
APInt N = SmallCst->getValue().zext(BigBitSize) | BigCst->getValue();
Value *NewVal = ConstantInt::get(AndCst->getType()->getContext(), N);
return Builder->CreateICmp(LHSCC, NewAnd, NewVal);
}
}
}
// From here on, we only handle:
// (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
if (Val != Val2) return nullptr;
// ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
return nullptr;
// Make a constant range that's the intersection of the two icmp ranges.
// If the intersection is empty, we know that the result is false.
ConstantRange LHSRange =
ConstantRange::makeAllowedICmpRegion(LHSCC, LHSCst->getValue());
ConstantRange RHSRange =
ConstantRange::makeAllowedICmpRegion(RHSCC, RHSCst->getValue());
if (LHSRange.intersectWith(RHSRange).isEmptySet())
return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
// We can't fold (ugt x, C) & (sgt x, C2).
if (!PredicatesFoldable(LHSCC, RHSCC))
return nullptr;
// Ensure that the larger constant is on the RHS.
bool ShouldSwap;
if (CmpInst::isSigned(LHSCC) ||
(ICmpInst::isEquality(LHSCC) &&
CmpInst::isSigned(RHSCC)))
ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
else
ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
if (ShouldSwap) {
std::swap(LHS, RHS);
std::swap(LHSCst, RHSCst);
std::swap(LHSCC, RHSCC);
}
// At this point, we know we have two icmp instructions
// comparing a value against two constants and and'ing the result
// together. Because of the above check, we know that we only have
// icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
// (from the icmp folding check above), that the two constants
// are not equal and that the larger constant is on the RHS
assert(LHSCst != RHSCst && "Compares not folded above?");
switch (LHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
return LHS;
}
case ICmpInst::ICMP_NE:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_ULT:
if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
return Builder->CreateICmpULT(Val, LHSCst);
if (LHSCst->isNullValue()) // (X != 0 & X u< 14) -> X-1 u< 13
return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, false, true);
break; // (X != 13 & X u< 15) -> no change
case ICmpInst::ICMP_SLT:
if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
return Builder->CreateICmpSLT(Val, LHSCst);
break; // (X != 13 & X s< 15) -> no change
case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
return RHS;
case ICmpInst::ICMP_NE:
// Special case to get the ordering right when the values wrap around
// zero.
if (LHSCst->getValue() == 0 && RHSCst->getValue().isAllOnesValue())
std::swap(LHSCst, RHSCst);
if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
return Builder->CreateICmpUGT(Add, ConstantInt::get(Add->getType(), 1),
Val->getName()+".cmp");
}
break; // (X != 13 & X != 15) -> no change
}
break;
case ICmpInst::ICMP_ULT:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
break;
case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
return LHS;
case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
break;
}
break;
case ICmpInst::ICMP_SLT:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
break;
case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
return LHS;
case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
break;
}
break;
case ICmpInst::ICMP_UGT:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15
case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
return RHS;
case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
break;
case ICmpInst::ICMP_NE:
if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
return Builder->CreateICmp(LHSCC, Val, RHSCst);
break; // (X u> 13 & X != 15) -> no change
case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1
return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, false, true);
case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
break;
}
break;
case ICmpInst::ICMP_SGT:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15
case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
return RHS;
case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
break;
case ICmpInst::ICMP_NE:
if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
return Builder->CreateICmp(LHSCC, Val, RHSCst);
break; // (X s> 13 & X != 15) -> no change
case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1
return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, true, true);
case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
break;
}
break;
}
return nullptr;
}
/// Optimize (fcmp)&(fcmp). NOTE: Unlike the rest of instcombine, this returns
/// a Value which should already be inserted into the function.
Value *InstCombiner::FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS) {
if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
RHS->getPredicate() == FCmpInst::FCMP_ORD) {
if (LHS->getOperand(0)->getType() != RHS->getOperand(0)->getType())
return nullptr;
// (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y)
if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
// If either of the constants are nans, then the whole thing returns
// false.
if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
return Builder->getFalse();
return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0));
}
// Handle vector zeros. This occurs because the canonical form of
// "fcmp ord x,x" is "fcmp ord x, 0".
if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
isa<ConstantAggregateZero>(RHS->getOperand(1)))
return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0));
return nullptr;
}
Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
// Swap RHS operands to match LHS.
Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
std::swap(Op1LHS, Op1RHS);
}
if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
// Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
if (Op0CC == Op1CC)
return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
if (Op0CC == FCmpInst::FCMP_FALSE || Op1CC == FCmpInst::FCMP_FALSE)
return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
if (Op0CC == FCmpInst::FCMP_TRUE)
return RHS;
if (Op1CC == FCmpInst::FCMP_TRUE)
return LHS;
bool Op0Ordered;
bool Op1Ordered;
unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
// uno && ord -> false
if (Op0Pred == 0 && Op1Pred == 0 && Op0Ordered != Op1Ordered)
return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
if (Op1Pred == 0) {
std::swap(LHS, RHS);
std::swap(Op0Pred, Op1Pred);
std::swap(Op0Ordered, Op1Ordered);
}
if (Op0Pred == 0) {
// uno && ueq -> uno && (uno || eq) -> uno
// ord && olt -> ord && (ord && lt) -> olt
if (!Op0Ordered && (Op0Ordered == Op1Ordered))
return LHS;
if (Op0Ordered && (Op0Ordered == Op1Ordered))
return RHS;
// uno && oeq -> uno && (ord && eq) -> false
if (!Op0Ordered)
return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
// ord && ueq -> ord && (uno || eq) -> oeq
return getFCmpValue(true, Op1Pred, Op0LHS, Op0RHS, Builder);
}
}
return nullptr;
}
/// Match De Morgan's Laws:
/// (~A & ~B) == (~(A | B))
/// (~A | ~B) == (~(A & B))
static Instruction *matchDeMorgansLaws(BinaryOperator &I,
InstCombiner::BuilderTy *Builder) {
auto Opcode = I.getOpcode();
assert((Opcode == Instruction::And || Opcode == Instruction::Or) &&
"Trying to match De Morgan's Laws with something other than and/or");
// Flip the logic operation.
if (Opcode == Instruction::And)
Opcode = Instruction::Or;
else
Opcode = Instruction::And;
Value *Op0 = I.getOperand(0);
Value *Op1 = I.getOperand(1);
// TODO: Use pattern matchers instead of dyn_cast.
if (Value *Op0NotVal = dyn_castNotVal(Op0))
if (Value *Op1NotVal = dyn_castNotVal(Op1))
if (Op0->hasOneUse() && Op1->hasOneUse()) {
Value *LogicOp = Builder->CreateBinOp(Opcode, Op0NotVal, Op1NotVal,
I.getName() + ".demorgan");
return BinaryOperator::CreateNot(LogicOp);
}
// De Morgan's Law in disguise:
// (zext(bool A) ^ 1) & (zext(bool B) ^ 1) -> zext(~(A | B))
// (zext(bool A) ^ 1) | (zext(bool B) ^ 1) -> zext(~(A & B))
Value *A = nullptr;
Value *B = nullptr;
ConstantInt *C1 = nullptr;
if (match(Op0, m_OneUse(m_Xor(m_ZExt(m_Value(A)), m_ConstantInt(C1)))) &&
match(Op1, m_OneUse(m_Xor(m_ZExt(m_Value(B)), m_Specific(C1))))) {
// TODO: This check could be loosened to handle different type sizes.
// Alternatively, we could fix the definition of m_Not to recognize a not
// operation hidden by a zext?
if (A->getType()->isIntegerTy(1) && B->getType()->isIntegerTy(1) &&
C1->isOne()) {
Value *LogicOp = Builder->CreateBinOp(Opcode, A, B,
I.getName() + ".demorgan");
Value *Not = Builder->CreateNot(LogicOp);
return CastInst::CreateZExtOrBitCast(Not, I.getType());
}
}
return nullptr;
}
Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
bool Changed = SimplifyAssociativeOrCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyVectorOp(I))
return ReplaceInstUsesWith(I, V);
if (Value *V = SimplifyAndInst(Op0, Op1, DL, TLI, DT, AC))
return ReplaceInstUsesWith(I, V);
// (A|B)&(A|C) -> A|(B&C) etc
if (Value *V = SimplifyUsingDistributiveLaws(I))
return ReplaceInstUsesWith(I, V);
// See if we can simplify any instructions used by the instruction whose sole
// purpose is to compute bits we don't care about.
if (SimplifyDemandedInstructionBits(I))
return &I;
if (Value *V = SimplifyBSwap(I))
return ReplaceInstUsesWith(I, V);
if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
const APInt &AndRHSMask = AndRHS->getValue();
// Optimize a variety of ((val OP C1) & C2) combinations...
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
Value *Op0LHS = Op0I->getOperand(0);
Value *Op0RHS = Op0I->getOperand(1);
switch (Op0I->getOpcode()) {
default: break;
case Instruction::Xor:
case Instruction::Or: {
// If the mask is only needed on one incoming arm, push it up.
if (!Op0I->hasOneUse()) break;
APInt NotAndRHS(~AndRHSMask);
if (MaskedValueIsZero(Op0LHS, NotAndRHS, 0, &I)) {
// Not masking anything out for the LHS, move to RHS.
Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS,
Op0RHS->getName()+".masked");
return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS);
}
if (!isa<Constant>(Op0RHS) &&
MaskedValueIsZero(Op0RHS, NotAndRHS, 0, &I)) {
// Not masking anything out for the RHS, move to LHS.
Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS,
Op0LHS->getName()+".masked");
return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS);
}
break;
}
case Instruction::Add:
// ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
// ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
// ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
return BinaryOperator::CreateAnd(V, AndRHS);
if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes
break;
case Instruction::Sub:
// ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
// ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
// ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
return BinaryOperator::CreateAnd(V, AndRHS);
// -x & 1 -> x & 1
if (AndRHSMask == 1 && match(Op0LHS, m_Zero()))
return BinaryOperator::CreateAnd(Op0RHS, AndRHS);
// (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
// has 1's for all bits that the subtraction with A might affect.
if (Op0I->hasOneUse() && !match(Op0LHS, m_Zero())) {
uint32_t BitWidth = AndRHSMask.getBitWidth();
uint32_t Zeros = AndRHSMask.countLeadingZeros();
APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
if (MaskedValueIsZero(Op0LHS, Mask, 0, &I)) {
Value *NewNeg = Builder->CreateNeg(Op0RHS);
return BinaryOperator::CreateAnd(NewNeg, AndRHS);
}
}
break;
case Instruction::Shl:
case Instruction::LShr:
// (1 << x) & 1 --> zext(x == 0)
// (1 >> x) & 1 --> zext(x == 0)
if (AndRHSMask == 1 && Op0LHS == AndRHS) {
Value *NewICmp =
Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType()));
return new ZExtInst(NewICmp, I.getType());
}
break;
}
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
return Res;
}
// If this is an integer truncation, and if the source is an 'and' with
// immediate, transform it. This frequently occurs for bitfield accesses.
{
Value *X = nullptr; ConstantInt *YC = nullptr;
if (match(Op0, m_Trunc(m_And(m_Value(X), m_ConstantInt(YC))))) {
// Change: and (trunc (and X, YC) to T), C2
// into : and (trunc X to T), trunc(YC) & C2
// This will fold the two constants together, which may allow
// other simplifications.
Value *NewCast = Builder->CreateTrunc(X, I.getType(), "and.shrunk");
Constant *C3 = ConstantExpr::getTrunc(YC, I.getType());
C3 = ConstantExpr::getAnd(C3, AndRHS);
return BinaryOperator::CreateAnd(NewCast, C3);
}
}
// Try to fold constant and into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldOpIntoSelect(I, SI))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
}
if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder))
return DeMorgan;
{
Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
// (A|B) & ~(A&B) -> A^B
if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
match(Op1, m_Not(m_And(m_Value(C), m_Value(D)))) &&
((A == C && B == D) || (A == D && B == C)))
return BinaryOperator::CreateXor(A, B);
// ~(A&B) & (A|B) -> A^B
if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
match(Op0, m_Not(m_And(m_Value(C), m_Value(D)))) &&
((A == C && B == D) || (A == D && B == C)))
return BinaryOperator::CreateXor(A, B);
// A&(A^B) => A & ~B
{
Value *tmpOp0 = Op0;
Value *tmpOp1 = Op1;
if (Op0->hasOneUse() &&
match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
if (A == Op1 || B == Op1 ) {
tmpOp1 = Op0;
tmpOp0 = Op1;
// Simplify below
}
}
if (tmpOp1->hasOneUse() &&
match(tmpOp1, m_Xor(m_Value(A), m_Value(B)))) {
if (B == tmpOp0) {
std::swap(A, B);
}
// Notice that the patten (A&(~B)) is actually (A&(-1^B)), so if
// A is originally -1 (or a vector of -1 and undefs), then we enter
// an endless loop. By checking that A is non-constant we ensure that
// we will never get to the loop.
if (A == tmpOp0 && !isa<Constant>(A)) // A&(A^B) -> A & ~B
return BinaryOperator::CreateAnd(A, Builder->CreateNot(B));
}
}
// (A&((~A)|B)) -> A&B
if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) ||
match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1)))))
return BinaryOperator::CreateAnd(A, Op1);
if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
return BinaryOperator::CreateAnd(A, Op0);
// (A ^ B) & ((B ^ C) ^ A) -> (A ^ B) & ~C
if (match(Op0, m_Xor(m_Value(A), m_Value(B))))
if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A))))
if (Op1->hasOneUse() || cast<BinaryOperator>(Op1)->hasOneUse())
return BinaryOperator::CreateAnd(Op0, Builder->CreateNot(C));
// ((A ^ C) ^ B) & (B ^ A) -> (B ^ A) & ~C
if (match(Op0, m_Xor(m_Xor(m_Value(A), m_Value(C)), m_Value(B))))
if (match(Op1, m_Xor(m_Specific(B), m_Specific(A))))
if (Op0->hasOneUse() || cast<BinaryOperator>(Op0)->hasOneUse())
return BinaryOperator::CreateAnd(Op1, Builder->CreateNot(C));
// (A | B) & ((~A) ^ B) -> (A & B)
if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
match(Op1, m_Xor(m_Not(m_Specific(A)), m_Specific(B))))
return BinaryOperator::CreateAnd(A, B);
// ((~A) ^ B) & (A | B) -> (A & B)
if (match(Op0, m_Xor(m_Not(m_Value(A)), m_Value(B))) &&
match(Op1, m_Or(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateAnd(A, B);
}
{
ICmpInst *LHS = dyn_cast<ICmpInst>(Op0);
ICmpInst *RHS = dyn_cast<ICmpInst>(Op1);
if (LHS && RHS)
if (Value *Res = FoldAndOfICmps(LHS, RHS))
return ReplaceInstUsesWith(I, Res);
// TODO: Make this recursive; it's a little tricky because an arbitrary
// number of 'and' instructions might have to be created.
Value *X, *Y;
if (LHS && match(Op1, m_OneUse(m_And(m_Value(X), m_Value(Y))))) {
if (auto *Cmp = dyn_cast<ICmpInst>(X))
if (Value *Res = FoldAndOfICmps(LHS, Cmp))
return ReplaceInstUsesWith(I, Builder->CreateAnd(Res, Y));
if (auto *Cmp = dyn_cast<ICmpInst>(Y))
if (Value *Res = FoldAndOfICmps(LHS, Cmp))
return ReplaceInstUsesWith(I, Builder->CreateAnd(Res, X));
}
if (RHS && match(Op0, m_OneUse(m_And(m_Value(X), m_Value(Y))))) {
if (auto *Cmp = dyn_cast<ICmpInst>(X))
if (Value *Res = FoldAndOfICmps(Cmp, RHS))
return ReplaceInstUsesWith(I, Builder->CreateAnd(Res, Y));
if (auto *Cmp = dyn_cast<ICmpInst>(Y))
if (Value *Res = FoldAndOfICmps(Cmp, RHS))
return ReplaceInstUsesWith(I, Builder->CreateAnd(Res, X));
}
}
// If and'ing two fcmp, try combine them into one.
if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
if (Value *Res = FoldAndOfFCmps(LHS, RHS))
return ReplaceInstUsesWith(I, Res);
if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
Value *Op0COp = Op0C->getOperand(0);
Type *SrcTy = Op0COp->getType();
// fold (and (cast A), (cast B)) -> (cast (and A, B))
if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) {
if (Op0C->getOpcode() == Op1C->getOpcode() && // same cast kind ?
SrcTy == Op1C->getOperand(0)->getType() &&
SrcTy->isIntOrIntVectorTy()) {
Value *Op1COp = Op1C->getOperand(0);
// Only do this if the casts both really cause code to be generated.
if (ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) &&
ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) {
Value *NewOp = Builder->CreateAnd(Op0COp, Op1COp, I.getName());
return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
}
// If this is and(cast(icmp), cast(icmp)), try to fold this even if the
// cast is otherwise not optimizable. This happens for vector sexts.
if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1COp))
if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0COp))
if (Value *Res = FoldAndOfICmps(LHS, RHS))
return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
// If this is and(cast(fcmp), cast(fcmp)), try to fold this even if the
// cast is otherwise not optimizable. This happens for vector sexts.
if (FCmpInst *RHS = dyn_cast<FCmpInst>(Op1COp))
if (FCmpInst *LHS = dyn_cast<FCmpInst>(Op0COp))
if (Value *Res = FoldAndOfFCmps(LHS, RHS))
return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
}
}
// If we are masking off the sign bit of a floating-point value, convert
// this to the canonical fabs intrinsic call and cast back to integer.
// The backend should know how to optimize fabs().
// TODO: This transform should also apply to vectors.
ConstantInt *CI;
if (isa<BitCastInst>(Op0C) && SrcTy->isFloatingPointTy() &&
match(Op1, m_ConstantInt(CI)) && CI->isMaxValue(true)) {
Module *M = I.getModule();
Function *Fabs = Intrinsic::getDeclaration(M, Intrinsic::fabs, SrcTy);
Value *Call = Builder->CreateCall(Fabs, Op0COp, "fabs");
return CastInst::CreateBitOrPointerCast(Call, I.getType());
}
}
{
Value *X = nullptr;
bool OpsSwapped = false;
// Canonicalize SExt or Not to the LHS
if (match(Op1, m_SExt(m_Value())) ||
match(Op1, m_Not(m_Value()))) {
std::swap(Op0, Op1);
OpsSwapped = true;
}
// Fold (and (sext bool to A), B) --> (select bool, B, 0)
if (match(Op0, m_SExt(m_Value(X))) &&
X->getType()->getScalarType()->isIntegerTy(1)) {
Value *Zero = Constant::getNullValue(Op1->getType());
return SelectInst::Create(X, Op1, Zero);
}
// Fold (and ~(sext bool to A), B) --> (select bool, 0, B)
if (match(Op0, m_Not(m_SExt(m_Value(X)))) &&
X->getType()->getScalarType()->isIntegerTy(1)) {
Value *Zero = Constant::getNullValue(Op0->getType());
return SelectInst::Create(X, Zero, Op1);
}
if (OpsSwapped)
std::swap(Op0, Op1);
}
return Changed ? &I : nullptr;
}
/// Analyze the specified subexpression and see if it is capable of providing
/// pieces of a bswap or bitreverse. The subexpression provides a potential
/// piece of a bswap or bitreverse if it can be proven that each non-zero bit in
/// the output of the expression came from a corresponding bit in some other
/// value. This function is recursive, and the end result is a mapping of
/// (value, bitnumber) to bitnumber. It is the caller's responsibility to
/// validate that all `value`s are identical and that the bitnumber to bitnumber
/// mapping is correct for a bswap or bitreverse.
///
/// For example, if the current subexpression if "(shl i32 %X, 24)" then we know
/// that the expression deposits the low byte of %X into the high byte of the
/// result and that all other bits are zero. This expression is accepted,
/// BitValues[24-31] are set to %X and BitProvenance[24-31] are set to [0-7].
///
/// 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 bits that the subexpression is later shifted. For
/// example, if the expression is later right shifted by 16 bits, the
/// OverallLeftShift value would be -16 on entry. This is used to specify which
/// bits of BitValues are actually being set.
///
/// Similarly, BitMask is a bitmask where a bit is clear if its corresponding
/// bit is masked to zero by a user. For example, in (X & 255), X will be
/// processed with a bytemask of 255. BitMask is always in the local
/// (OverallLeftShift) coordinate space.
///
static bool CollectBitParts(Value *V, int OverallLeftShift, APInt BitMask,
SmallVectorImpl<Value *> &BitValues,
SmallVectorImpl<int> &BitProvenance) {
if (Instruction *I = dyn_cast<Instruction>(V)) {
// If this is an or instruction, it may be an inner node of the bswap.
if (I->getOpcode() == Instruction::Or)
return CollectBitParts(I->getOperand(0), OverallLeftShift, BitMask,
BitValues, BitProvenance) ||
CollectBitParts(I->getOperand(1), OverallLeftShift, BitMask,
BitValues, BitProvenance);
// If this is a logical shift by a constant, recurse with OverallLeftShift
// and BitMask adjusted.
if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
unsigned ShAmt =
cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
// Ensure the shift amount is defined.
if (ShAmt > BitValues.size())
return true;
unsigned BitShift = ShAmt;
if (I->getOpcode() == Instruction::Shl) {
// X << C -> collect(X, +C)
OverallLeftShift += BitShift;
BitMask = BitMask.lshr(BitShift);
} else {
// X >>u C -> collect(X, -C)
OverallLeftShift -= BitShift;
BitMask = BitMask.shl(BitShift);
}
if (OverallLeftShift >= (int)BitValues.size())
return true;
if (OverallLeftShift <= -(int)BitValues.size())
return true;
return CollectBitParts(I->getOperand(0), OverallLeftShift, BitMask,
BitValues, BitProvenance);
}
// If this is a logical 'and' with a mask that clears bits, clear the
// corresponding bits in BitMask.
if (I->getOpcode() == Instruction::And &&
isa<ConstantInt>(I->getOperand(1))) {
unsigned NumBits = BitValues.size();
APInt Bit(I->getType()->getPrimitiveSizeInBits(), 1);
const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
for (unsigned i = 0; i != NumBits; ++i, Bit <<= 1) {
// If this bit is masked out by a later operation, we don't care what
// the and mask is.
if (BitMask[i] == 0)
continue;
// If the AndMask is zero for this bit, clear the bit.
APInt MaskB = AndMask & Bit;
if (MaskB == 0) {
BitMask.clearBit(i);
continue;
}
// Otherwise, this bit is kept.
}
return CollectBitParts(I->getOperand(0), OverallLeftShift, BitMask,
BitValues, BitProvenance);
}
}
// Okay, we got to something that isn't a shift, 'or' or 'and'. This must be
// the input value to the bswap/bitreverse. To be part of a bswap or
// bitreverse we must be demanding a contiguous range of bits from it.
unsigned InputBitLen = BitMask.countPopulation();
unsigned InputBitNo = BitMask.countTrailingZeros();
if (BitMask.getBitWidth() - BitMask.countLeadingZeros() - InputBitNo !=
InputBitLen)
// Not a contiguous set range of bits!
return true;
// We know we're moving a contiguous range of bits from the input to the
// output. Record which bits in the output came from which bits in the input.
unsigned DestBitNo = InputBitNo + OverallLeftShift;
for (unsigned I = 0; I < InputBitLen; ++I)
BitProvenance[DestBitNo + I] = InputBitNo + I;
// If the destination bit value is already defined, the values are or'd
// together, which isn't a bswap/bitreverse (unless it's an or of the same
// bits).
if (BitValues[DestBitNo] && BitValues[DestBitNo] != V)
return true;
for (unsigned I = 0; I < InputBitLen; ++I)
BitValues[DestBitNo + I] = V;
return false;
}
static bool bitTransformIsCorrectForBSwap(unsigned From, unsigned To,
unsigned BitWidth) {
if (From % 8 != To % 8)
return false;
// Convert from bit indices to byte indices and check for a byte reversal.
From >>= 3;
To >>= 3;
BitWidth >>= 3;
return From == BitWidth - To - 1;
}
static bool bitTransformIsCorrectForBitReverse(unsigned From, unsigned To,
unsigned BitWidth) {
return From == BitWidth - To - 1;
}
/// Given an OR instruction, check to see if this is a bswap or bitreverse
/// idiom. If so, insert the new intrinsic and return it.
Instruction *InstCombiner::MatchBSwapOrBitReverse(BinaryOperator &I) {
IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
if (!ITy)
return nullptr; // Can't do vectors.
unsigned BW = ITy->getBitWidth();
/// We keep track of which bit (BitProvenance) inside which value (BitValues)
/// defines each bit in the result.
SmallVector<Value *, 8> BitValues(BW, nullptr);
SmallVector<int, 8> BitProvenance(BW, -1);
// Try to find all the pieces corresponding to the bswap.
APInt BitMask = APInt::getAllOnesValue(BitValues.size());
if (CollectBitParts(&I, 0, BitMask, BitValues, BitProvenance))
return nullptr;
// Check to see if all of the bits come from the same value.
Value *V = BitValues[0];
if (!V) return nullptr; // Didn't find a bit? Must be zero.
if (!std::all_of(BitValues.begin(), BitValues.end(),
[&](const Value *X) { return X == V; }))
return nullptr;
// Now, is the bit permutation correct for a bswap or a bitreverse? We can
// only byteswap values with an even number of bytes.
bool OKForBSwap = BW % 16 == 0, OKForBitReverse = true;;
for (unsigned i = 0, e = BitValues.size(); i != e; ++i) {
OKForBSwap &= bitTransformIsCorrectForBSwap(BitProvenance[i], i, BW);
OKForBitReverse &=
bitTransformIsCorrectForBitReverse(BitProvenance[i], i, BW);
}
Intrinsic::ID Intrin;
if (OKForBSwap)
Intrin = Intrinsic::bswap;
else if (OKForBitReverse)
Intrin = Intrinsic::bitreverse;
else
return nullptr;
Function *F = Intrinsic::getDeclaration(I.getModule(), Intrin, ITy);
return CallInst::Create(F, V);
}
/// 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".
static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
Value *C, Value *D) {
// If A is not a select of -1/0, this cannot match.
Value *Cond = nullptr;
if (!match(A, m_SExt(m_Value(Cond))) ||
!Cond->getType()->isIntegerTy(1))
return nullptr;
// ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B.
if (match(D, m_Not(m_SExt(m_Specific(Cond)))))
return SelectInst::Create(Cond, C, B);
if (match(D, m_SExt(m_Not(m_Specific(Cond)))))
return SelectInst::Create(Cond, C, B);
// ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D.
if (match(B, m_Not(m_SExt(m_Specific(Cond)))))
return SelectInst::Create(Cond, C, D);
if (match(B, m_SExt(m_Not(m_Specific(Cond)))))
return SelectInst::Create(Cond, C, D);
return nullptr;
}
/// Fold (icmp)|(icmp) if possible.
Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
Instruction *CxtI) {
ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
// Fold (iszero(A & K1) | iszero(A & K2)) -> (A & (K1 | K2)) != (K1 | K2)
// if K1 and K2 are a one-bit mask.
ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1));
ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1));
if (LHS->getPredicate() == ICmpInst::ICMP_EQ && LHSCst && LHSCst->isZero() &&
RHS->getPredicate() == ICmpInst::ICMP_EQ && RHSCst && RHSCst->isZero()) {
BinaryOperator *LAnd = dyn_cast<BinaryOperator>(LHS->getOperand(0));
BinaryOperator *RAnd = dyn_cast<BinaryOperator>(RHS->getOperand(0));
if (LAnd && RAnd && LAnd->hasOneUse() && RHS->hasOneUse() &&
LAnd->getOpcode() == Instruction::And &&
RAnd->getOpcode() == Instruction::And) {
Value *Mask = nullptr;
Value *Masked = nullptr;
if (LAnd->getOperand(0) == RAnd->getOperand(0) &&
isKnownToBeAPowerOfTwo(LAnd->getOperand(1), DL, false, 0, AC, CxtI,
DT) &&
isKnownToBeAPowerOfTwo(RAnd->getOperand(1), DL, false, 0, AC, CxtI,
DT)) {
Mask = Builder->CreateOr(LAnd->getOperand(1), RAnd->getOperand(1));
Masked = Builder->CreateAnd(LAnd->getOperand(0), Mask);
} else if (LAnd->getOperand(1) == RAnd->getOperand(1) &&
isKnownToBeAPowerOfTwo(LAnd->getOperand(0), DL, false, 0, AC,
CxtI, DT) &&
isKnownToBeAPowerOfTwo(RAnd->getOperand(0), DL, false, 0, AC,
CxtI, DT)) {
Mask = Builder->CreateOr(LAnd->getOperand(0), RAnd->getOperand(0));
Masked = Builder->CreateAnd(LAnd->getOperand(1), Mask);
}
if (Masked)
return Builder->CreateICmp(ICmpInst::ICMP_NE, Masked, Mask);
}
}
// Fold (icmp ult/ule (A + C1), C3) | (icmp ult/ule (A + C2), C3)
// --> (icmp ult/ule ((A & ~(C1 ^ C2)) + max(C1, C2)), C3)
// The original condition actually refers to the following two ranges:
// [MAX_UINT-C1+1, MAX_UINT-C1+1+C3] and [MAX_UINT-C2+1, MAX_UINT-C2+1+C3]
// We can fold these two ranges if:
// 1) C1 and C2 is unsigned greater than C3.
// 2) The two ranges are separated.
// 3) C1 ^ C2 is one-bit mask.
// 4) LowRange1 ^ LowRange2 and HighRange1 ^ HighRange2 are one-bit mask.
// This implies all values in the two ranges differ by exactly one bit.
if ((LHSCC == ICmpInst::ICMP_ULT || LHSCC == ICmpInst::ICMP_ULE) &&
LHSCC == RHSCC && LHSCst && RHSCst && LHS->hasOneUse() &&
RHS->hasOneUse() && LHSCst->getType() == RHSCst->getType() &&
LHSCst->getValue() == (RHSCst->getValue())) {
Value *LAdd = LHS->getOperand(0);
Value *RAdd = RHS->getOperand(0);
Value *LAddOpnd, *RAddOpnd;
ConstantInt *LAddCst, *RAddCst;
if (match(LAdd, m_Add(m_Value(LAddOpnd), m_ConstantInt(LAddCst))) &&
match(RAdd, m_Add(m_Value(RAddOpnd), m_ConstantInt(RAddCst))) &&
LAddCst->getValue().ugt(LHSCst->getValue()) &&
RAddCst->getValue().ugt(LHSCst->getValue())) {
APInt DiffCst = LAddCst->getValue() ^ RAddCst->getValue();
if (LAddOpnd == RAddOpnd && DiffCst.isPowerOf2()) {
ConstantInt *MaxAddCst = nullptr;
if (LAddCst->getValue().ult(RAddCst->getValue()))
MaxAddCst = RAddCst;
else
MaxAddCst = LAddCst;
APInt RRangeLow = -RAddCst->getValue();
APInt RRangeHigh = RRangeLow + LHSCst->getValue();
APInt LRangeLow = -LAddCst->getValue();
APInt LRangeHigh = LRangeLow + LHSCst->getValue();
APInt LowRangeDiff = RRangeLow ^ LRangeLow;
APInt HighRangeDiff = RRangeHigh ^ LRangeHigh;
APInt RangeDiff = LRangeLow.sgt(RRangeLow) ? LRangeLow - RRangeLow
: RRangeLow - LRangeLow;
if (LowRangeDiff.isPowerOf2() && LowRangeDiff == HighRangeDiff &&
RangeDiff.ugt(LHSCst->getValue())) {
Value *MaskCst = ConstantInt::get(LAddCst->getType(), ~DiffCst);
Value *NewAnd = Builder->CreateAnd(LAddOpnd, MaskCst);
Value *NewAdd = Builder->CreateAdd(NewAnd, MaxAddCst);
return (Builder->CreateICmp(LHS->getPredicate(), NewAdd, LHSCst));
}
}
}
}
// (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
if (PredicatesFoldable(LHSCC, RHSCC)) {
if (LHS->getOperand(0) == RHS->getOperand(1) &&
LHS->getOperand(1) == RHS->getOperand(0))
LHS->swapOperands();
if (LHS->getOperand(0) == RHS->getOperand(0) &&
LHS->getOperand(1) == RHS->getOperand(1)) {
Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
unsigned Code = getICmpCode(LHS) | getICmpCode(RHS);
bool isSigned = LHS->isSigned() || RHS->isSigned();
return getNewICmpValue(isSigned, Code, Op0, Op1, Builder);
}
}
// handle (roughly):
// (icmp ne (A & B), C) | (icmp ne (A & D), E)
if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, false, Builder))
return V;
Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0);
if (LHS->hasOneUse() || RHS->hasOneUse()) {
// (icmp eq B, 0) | (icmp ult A, B) -> (icmp ule A, B-1)
// (icmp eq B, 0) | (icmp ugt B, A) -> (icmp ule A, B-1)
Value *A = nullptr, *B = nullptr;
if (LHSCC == ICmpInst::ICMP_EQ && LHSCst && LHSCst->isZero()) {
B = Val;
if (RHSCC == ICmpInst::ICMP_ULT && Val == RHS->getOperand(1))
A = Val2;
else if (RHSCC == ICmpInst::ICMP_UGT && Val == Val2)
A = RHS->getOperand(1);
}
// (icmp ult A, B) | (icmp eq B, 0) -> (icmp ule A, B-1)
// (icmp ugt B, A) | (icmp eq B, 0) -> (icmp ule A, B-1)
else if (RHSCC == ICmpInst::ICMP_EQ && RHSCst && RHSCst->isZero()) {
B = Val2;
if (LHSCC == ICmpInst::ICMP_ULT && Val2 == LHS->getOperand(1))
A = Val;
else if (LHSCC == ICmpInst::ICMP_UGT && Val2 == Val)
A = LHS->getOperand(1);
}
if (A && B)
return Builder->CreateICmp(
ICmpInst::ICMP_UGE,
Builder->CreateAdd(B, ConstantInt::getSigned(B->getType(), -1)), A);
}
// E.g. (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n
if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/true))
return V;
// E.g. (icmp sgt x, n) | (icmp slt x, 0) --> icmp ugt x, n
if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/true))
return V;
// This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
if (!LHSCst || !RHSCst) return nullptr;
if (LHSCst == RHSCst && LHSCC == RHSCC) {
// (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
if (LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
Value *NewOr = Builder->CreateOr(Val, Val2);
return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
}
}
// (icmp ult (X + CA), C1) | (icmp eq X, C2) -> (icmp ule (X + CA), C1)
// iff C2 + CA == C1.
if (LHSCC == ICmpInst::ICMP_ULT && RHSCC == ICmpInst::ICMP_EQ) {
ConstantInt *AddCst;
if (match(Val, m_Add(m_Specific(Val2), m_ConstantInt(AddCst))))
if (RHSCst->getValue() + AddCst->getValue() == LHSCst->getValue())
return Builder->CreateICmpULE(Val, LHSCst);
}
// From here on, we only handle:
// (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
if (Val != Val2) return nullptr;
// ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
return nullptr;
// We can't fold (ugt x, C) | (sgt x, C2).
if (!PredicatesFoldable(LHSCC, RHSCC))
return nullptr;
// Ensure that the larger constant is on the RHS.
bool ShouldSwap;
if (CmpInst::isSigned(LHSCC) ||
(ICmpInst::isEquality(LHSCC) &&
CmpInst::isSigned(RHSCC)))
ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
else
ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
if (ShouldSwap) {
std::swap(LHS, RHS);
std::swap(LHSCst, RHSCst);
std::swap(LHSCC, RHSCC);
}
// At this point, we know we have two icmp instructions
// comparing a value against two constants and or'ing the result
// together. Because of the above check, we know that we only have
// ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
// icmp folding check above), that the two constants are not
// equal.
assert(LHSCst != RHSCst && "Compares not folded above?");
switch (LHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ:
if (LHS->getOperand(0) == RHS->getOperand(0)) {
// if LHSCst and RHSCst differ only by one bit:
// (A == C1 || A == C2) -> (A | (C1 ^ C2)) == C2
assert(LHSCst->getValue().ule(LHSCst->getValue()));
APInt Xor = LHSCst->getValue() ^ RHSCst->getValue();
if (Xor.isPowerOf2()) {
Value *Cst = Builder->getInt(Xor);
Value *Or = Builder->CreateOr(LHS->getOperand(0), Cst);
return Builder->CreateICmp(ICmpInst::ICMP_EQ, Or, RHSCst);
}
}
if (LHSCst == SubOne(RHSCst)) {
// (X == 13 | X == 14) -> X-13 <u 2
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
return Builder->CreateICmpULT(Add, AddCST);
}
break; // (X == 13 | X == 15) -> no change
case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
break;
case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
return RHS;
}
break;
case ICmpInst::ICMP_NE:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
return LHS;
case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
return Builder->getTrue();
}
case ICmpInst::ICMP_ULT:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
break;
case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
// If RHSCst is [us]MAXINT, it is always false. Not handling
// this can cause overflow.
if (RHSCst->isMaxValue(false))
return LHS;
return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), false, false);
case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
break;
case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
return RHS;
case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
break;
}
break;
case ICmpInst::ICMP_SLT:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
break;
case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2
// If RHSCst is [us]MAXINT, it is always false. Not handling
// this can cause overflow.
if (RHSCst->isMaxValue(true))
return LHS;
return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), true, false);
case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
break;
case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
return RHS;
case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
break;
}
break;
case ICmpInst::ICMP_UGT:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
return LHS;
case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
break;
case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
return Builder->getTrue();
case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
break;
}
break;
case ICmpInst::ICMP_SGT:
switch (RHSCC) {
default: llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
return LHS;
case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
break;
case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
return Builder->getTrue();
case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
break;
}
break;
}
return nullptr;
}
/// Optimize (fcmp)|(fcmp). NOTE: Unlike the rest of instcombine, this returns
/// a Value which should already be inserted into the function.
Value *InstCombiner::FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS) {
if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
RHS->getPredicate() == FCmpInst::FCMP_UNO &&
LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) {
if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
// If either of the constants are nans, then the whole thing returns
// true.
if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
return Builder->getTrue();
// Otherwise, no need to compare the two constants, compare the
// rest.
return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0));
}
// Handle vector zeros. This occurs because the canonical form of
// "fcmp uno x,x" is "fcmp uno x, 0".
if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
isa<ConstantAggregateZero>(RHS->getOperand(1)))
return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0));
return nullptr;
}
Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
// Swap RHS operands to match LHS.
Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
std::swap(Op1LHS, Op1RHS);
}
if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
// Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y).
if (Op0CC == Op1CC)
return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
if (Op0CC == FCmpInst::FCMP_TRUE || Op1CC == FCmpInst::FCMP_TRUE)
return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
if (Op0CC == FCmpInst::FCMP_FALSE)
return RHS;
if (Op1CC == FCmpInst::FCMP_FALSE)
return LHS;
bool Op0Ordered;
bool Op1Ordered;
unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
if (Op0Ordered == Op1Ordered) {
// If both are ordered or unordered, return a new fcmp with
// or'ed predicates.
return getFCmpValue(Op0Ordered, Op0Pred|Op1Pred, Op0LHS, Op0RHS, Builder);
}
}
return nullptr;
}
/// This helper function folds:
///
/// ((A | B) & C1) | (B & C2)
///
/// into:
///
/// (A & C1) | B
///
/// when the XOR of the two constants is "all ones" (-1).
Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
Value *A, Value *B, Value *C) {
ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
if (!CI1) return nullptr;
Value *V1 = nullptr;
ConstantInt *CI2 = nullptr;
if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return nullptr;
APInt Xor = CI1->getValue() ^ CI2->getValue();
if (!Xor.isAllOnesValue()) return nullptr;
if (V1 == A || V1 == B) {
Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1);
return BinaryOperator::CreateOr(NewOp, V1);
}
return nullptr;
}
/// \brief This helper function folds:
///
/// ((A | B) & C1) ^ (B & C2)
///
/// into:
///
/// (A & C1) ^ B
///
/// when the XOR of the two constants is "all ones" (-1).
Instruction *InstCombiner::FoldXorWithConstants(BinaryOperator &I, Value *Op,
Value *A, Value *B, Value *C) {
ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
if (!CI1)
return nullptr;
Value *V1 = nullptr;
ConstantInt *CI2 = nullptr;
if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2))))
return nullptr;
APInt Xor = CI1->getValue() ^ CI2->getValue();
if (!Xor.isAllOnesValue())
return nullptr;
if (V1 == A || V1 == B) {
Value *NewOp = Builder->CreateAnd(V1 == A ? B : A, CI1);
return BinaryOperator::CreateXor(NewOp, V1);
}
return nullptr;
}
Instruction *InstCombiner::visitOr(BinaryOperator &I) {
bool Changed = SimplifyAssociativeOrCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyVectorOp(I))
return ReplaceInstUsesWith(I, V);
if (Value *V = SimplifyOrInst(Op0, Op1, DL, TLI, DT, AC))
return ReplaceInstUsesWith(I, V);
// (A&B)|(A&C) -> A&(B|C) etc
if (Value *V = SimplifyUsingDistributiveLaws(I))
return ReplaceInstUsesWith(I, V);
// See if we can simplify any instructions used by the instruction whose sole
// purpose is to compute bits we don't care about.
if (SimplifyDemandedInstructionBits(I))
return &I;
if (Value *V = SimplifyBSwap(I))
return ReplaceInstUsesWith(I, V);
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
ConstantInt *C1 = nullptr; Value *X = nullptr;
// (X & C1) | C2 --> (X | C2) & (C1|C2)
// iff (C1 & C2) == 0.
if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) &&
(RHS->getValue() & C1->getValue()) != 0 &&
Op0->hasOneUse()) {
Value *Or = Builder->CreateOr(X, RHS);
Or->takeName(Op0);
return BinaryOperator::CreateAnd(Or,
Builder->getInt(RHS->getValue() | C1->getValue()));
}
// (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) &&
Op0->hasOneUse()) {
Value *Or = Builder->CreateOr(X, RHS);
Or->takeName(Op0);
return BinaryOperator::CreateXor(Or,
Builder->getInt(C1->getValue() & ~RHS->getValue()));
}
// Try to fold constant and into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldOpIntoSelect(I, SI))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
}
Value *A = nullptr, *B = nullptr;
ConstantInt *C1 = nullptr, *C2 = nullptr;
// (A | B) | C and A | (B | C) -> bswap if possible.
bool OrOfOrs = match(Op0, m_Or(m_Value(), m_Value())) ||
match(Op1, m_Or(m_Value(), m_Value()));
// (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
bool OrOfShifts = match(Op0, m_LogicalShift(m_Value(), m_Value())) &&
match(Op1, m_LogicalShift(m_Value(), m_Value()));
// (A & B) | (C & D) -> bswap if possible.
bool OrOfAnds = match(Op0, m_And(m_Value(), m_Value())) &&
match(Op1, m_And(m_Value(), m_Value()));
if (OrOfOrs || OrOfShifts || OrOfAnds)
if (Instruction *BSwap = MatchBSwapOrBitReverse(I))
return BSwap;
// (X^C)|Y -> (X|Y)^C iff Y&C == 0
if (Op0->hasOneUse() &&
match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
MaskedValueIsZero(Op1, C1->getValue(), 0, &I)) {
Value *NOr = Builder->CreateOr(A, Op1);
NOr->takeName(Op0);
return BinaryOperator::CreateXor(NOr, C1);
}
// Y|(X^C) -> (X|Y)^C iff Y&C == 0
if (Op1->hasOneUse() &&
match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
MaskedValueIsZero(Op0, C1->getValue(), 0, &I)) {
Value *NOr = Builder->CreateOr(A, Op0);
NOr->takeName(Op0);
return BinaryOperator::CreateXor(NOr, C1);
}
// ((~A & B) | A) -> (A | B)
if (match(Op0, m_And(m_Not(m_Value(A)), m_Value(B))) &&
match(Op1, m_Specific(A)))
return BinaryOperator::CreateOr(A, B);
// ((A & B) | ~A) -> (~A | B)
if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
match(Op1, m_Not(m_Specific(A))))
return BinaryOperator::CreateOr(Builder->CreateNot(A), B);
// (A & (~B)) | (A ^ B) -> (A ^ B)
if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) &&
match(Op1, m_Xor(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateXor(A, B);
// (A ^ B) | ( A & (~B)) -> (A ^ B)
if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
match(Op1, m_And(m_Specific(A), m_Not(m_Specific(B)))))
return BinaryOperator::CreateXor(A, B);
// (A & C)|(B & D)
Value *C = nullptr, *D = nullptr;
if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
match(Op1, m_And(m_Value(B), m_Value(D)))) {
Value *V1 = nullptr, *V2 = nullptr;
C1 = dyn_cast<ConstantInt>(C);
C2 = dyn_cast<ConstantInt>(D);
if (C1 && C2) { // (A & C1)|(B & C2)
if ((C1->getValue() & C2->getValue()) == 0) {
// ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2)
// iff (C1&C2) == 0 and (N&~C1) == 0
if (match(A, m_Or(m_Value(V1), m_Value(V2))) &&
((V1 == B &&
MaskedValueIsZero(V2, ~C1->getValue(), 0, &I)) || // (V|N)
(V2 == B &&
MaskedValueIsZero(V1, ~C1->getValue(), 0, &I)))) // (N|V)
return BinaryOperator::CreateAnd(A,
Builder->getInt(C1->getValue()|C2->getValue()));
// Or commutes, try both ways.
if (match(B, m_Or(m_Value(V1), m_Value(V2))) &&
((V1 == A &&
MaskedValueIsZero(V2, ~C2->getValue(), 0, &I)) || // (V|N)
(V2 == A &&
MaskedValueIsZero(V1, ~C2->getValue(), 0, &I)))) // (N|V)
return BinaryOperator::CreateAnd(B,
Builder->getInt(C1->getValue()|C2->getValue()));
// ((V|C3)&C1) | ((V|C4)&C2) --> (V|C3|C4)&(C1|C2)
// iff (C1&C2) == 0 and (C3&~C1) == 0 and (C4&~C2) == 0.
ConstantInt *C3 = nullptr, *C4 = nullptr;
if (match(A, m_Or(m_Value(V1), m_ConstantInt(C3))) &&
(C3->getValue() & ~C1->getValue()) == 0 &&
match(B, m_Or(m_Specific(V1), m_ConstantInt(C4))) &&
(C4->getValue() & ~C2->getValue()) == 0) {
V2 = Builder->CreateOr(V1, ConstantExpr::getOr(C3, C4), "bitfield");
return BinaryOperator::CreateAnd(V2,
Builder->getInt(C1->getValue()|C2->getValue()));
}
}
}
// (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants.
// Don't do this for vector select idioms, the code generator doesn't handle
// them well yet.
if (!I.getType()->isVectorTy()) {
if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D))
return Match;
if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C))
return Match;
if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D))
return Match;
if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C))
return Match;
}
// ((A&~B)|(~A&B)) -> A^B
if ((match(C, m_Not(m_Specific(D))) &&
match(B, m_Not(m_Specific(A)))))
return BinaryOperator::CreateXor(A, D);
// ((~B&A)|(~A&B)) -> A^B
if ((match(A, m_Not(m_Specific(D))) &&
match(B, m_Not(m_Specific(C)))))
return BinaryOperator::CreateXor(C, D);
// ((A&~B)|(B&~A)) -> A^B
if ((match(C, m_Not(m_Specific(B))) &&
match(D, m_Not(m_Specific(A)))))
return BinaryOperator::CreateXor(A, B);
// ((~B&A)|(B&~A)) -> A^B
if ((match(A, m_Not(m_Specific(B))) &&
match(D, m_Not(m_Specific(C)))))
return BinaryOperator::CreateXor(C, B);
// ((A|B)&1)|(B&-2) -> (A&1) | B
if (match(A, m_Or(m_Value(V1), m_Specific(B))) ||
match(A, m_Or(m_Specific(B), m_Value(V1)))) {
Instruction *Ret = FoldOrWithConstants(I, Op1, V1, B, C);
if (Ret) return Ret;
}
// (B&-2)|((A|B)&1) -> (A&1) | B
if (match(B, m_Or(m_Specific(A), m_Value(V1))) ||
match(B, m_Or(m_Value(V1), m_Specific(A)))) {
Instruction *Ret = FoldOrWithConstants(I, Op0, A, V1, D);
if (Ret) return Ret;
}
// ((A^B)&1)|(B&-2) -> (A&1) ^ B
if (match(A, m_Xor(m_Value(V1), m_Specific(B))) ||
match(A, m_Xor(m_Specific(B), m_Value(V1)))) {
Instruction *Ret = FoldXorWithConstants(I, Op1, V1, B, C);
if (Ret) return Ret;
}
// (B&-2)|((A^B)&1) -> (A&1) ^ B
if (match(B, m_Xor(m_Specific(A), m_Value(V1))) ||
match(B, m_Xor(m_Value(V1), m_Specific(A)))) {
Instruction *Ret = FoldXorWithConstants(I, Op0, A, V1, D);
if (Ret) return Ret;
}
}
// (A ^ B) | ((B ^ C) ^ A) -> (A ^ B) | C
if (match(Op0, m_Xor(m_Value(A), m_Value(B))))
if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A))))
if (Op1->hasOneUse() || cast<BinaryOperator>(Op1)->hasOneUse())
return BinaryOperator::CreateOr(Op0, C);
// ((A ^ C) ^ B) | (B ^ A) -> (B ^ A) | C
if (match(Op0, m_Xor(m_Xor(m_Value(A), m_Value(C)), m_Value(B))))
if (match(Op1, m_Xor(m_Specific(B), m_Specific(A))))
if (Op0->hasOneUse() || cast<BinaryOperator>(Op0)->hasOneUse())
return BinaryOperator::CreateOr(Op1, C);
// ((B | C) & A) | B -> B | (A & C)
if (match(Op0, m_And(m_Or(m_Specific(Op1), m_Value(C)), m_Value(A))))
return BinaryOperator::CreateOr(Op1, Builder->CreateAnd(A, C));
if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder))
return DeMorgan;
// Canonicalize xor to the RHS.
bool SwappedForXor = false;
if (match(Op0, m_Xor(m_Value(), m_Value()))) {
std::swap(Op0, Op1);
SwappedForXor = true;
}
// A | ( A ^ B) -> A | B
// A | (~A ^ B) -> A | ~B
// (A & B) | (A ^ B)
if (match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
if (Op0 == A || Op0 == B)
return BinaryOperator::CreateOr(A, B);
if (match(Op0, m_And(m_Specific(A), m_Specific(B))) ||
match(Op0, m_And(m_Specific(B), m_Specific(A))))
return BinaryOperator::CreateOr(A, B);
if (Op1->hasOneUse() && match(A, m_Not(m_Specific(Op0)))) {
Value *Not = Builder->CreateNot(B, B->getName()+".not");
return BinaryOperator::CreateOr(Not, Op0);
}
if (Op1->hasOneUse() && match(B, m_Not(m_Specific(Op0)))) {
Value *Not = Builder->CreateNot(A, A->getName()+".not");
return BinaryOperator::CreateOr(Not, Op0);
}
}
// A | ~(A | B) -> A | ~B
// A | ~(A ^ B) -> A | ~B
if (match(Op1, m_Not(m_Value(A))))
if (BinaryOperator *B = dyn_cast<BinaryOperator>(A))
if ((Op0 == B->getOperand(0) || Op0 == B->getOperand(1)) &&
Op1->hasOneUse() && (B->getOpcode() == Instruction::Or ||
B->getOpcode() == Instruction::Xor)) {
Value *NotOp = Op0 == B->getOperand(0) ? B->getOperand(1) :
B->getOperand(0);
Value *Not = Builder->CreateNot(NotOp, NotOp->getName()+".not");
return BinaryOperator::CreateOr(Not, Op0);
}
// (A & B) | ((~A) ^ B) -> (~A ^ B)
if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
match(Op1, m_Xor(m_Not(m_Specific(A)), m_Specific(B))))
return BinaryOperator::CreateXor(Builder->CreateNot(A), B);
// ((~A) ^ B) | (A & B) -> (~A ^ B)
if (match(Op0, m_Xor(m_Not(m_Value(A)), m_Value(B))) &&
match(Op1, m_And(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateXor(Builder->CreateNot(A), B);
if (SwappedForXor)
std::swap(Op0, Op1);
{
ICmpInst *LHS = dyn_cast<ICmpInst>(Op0);
ICmpInst *RHS = dyn_cast<ICmpInst>(Op1);
if (LHS && RHS)
if (Value *Res = FoldOrOfICmps(LHS, RHS, &I))
return ReplaceInstUsesWith(I, Res);
// TODO: Make this recursive; it's a little tricky because an arbitrary
// number of 'or' instructions might have to be created.
Value *X, *Y;
if (LHS && match(Op1, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) {
if (auto *Cmp = dyn_cast<ICmpInst>(X))
if (Value *Res = FoldOrOfICmps(LHS, Cmp, &I))
return ReplaceInstUsesWith(I, Builder->CreateOr(Res, Y));
if (auto *Cmp = dyn_cast<ICmpInst>(Y))
if (Value *Res = FoldOrOfICmps(LHS, Cmp, &I))
return ReplaceInstUsesWith(I, Builder->CreateOr(Res, X));
}
if (RHS && match(Op0, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) {
if (auto *Cmp = dyn_cast<ICmpInst>(X))
if (Value *Res = FoldOrOfICmps(Cmp, RHS, &I))
return ReplaceInstUsesWith(I, Builder->CreateOr(Res, Y));
if (auto *Cmp = dyn_cast<ICmpInst>(Y))
if (Value *Res = FoldOrOfICmps(Cmp, RHS, &I))
return ReplaceInstUsesWith(I, Builder->CreateOr(Res, X));
}
}
// (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y)
if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
if (Value *Res = FoldOrOfFCmps(LHS, RHS))
return ReplaceInstUsesWith(I, Res);
// fold (or (cast A), (cast B)) -> (cast (or A, B))
if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
CastInst *Op1C = dyn_cast<CastInst>(Op1);
if (Op1C && Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
Type *SrcTy = Op0C->getOperand(0)->getType();
if (SrcTy == Op1C->getOperand(0)->getType() &&
SrcTy->isIntOrIntVectorTy()) {
Value *Op0COp = Op0C->getOperand(0), *Op1COp = Op1C->getOperand(0);
if ((!isa<ICmpInst>(Op0COp) || !isa<ICmpInst>(Op1COp)) &&
// Only do this if the casts both really cause code to be
// generated.
ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) &&
ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) {
Value *NewOp = Builder->CreateOr(Op0COp, Op1COp, I.getName());
return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
}
// If this is or(cast(icmp), cast(icmp)), try to fold this even if the
// cast is otherwise not optimizable. This happens for vector sexts.
if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1COp))
if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0COp))
if (Value *Res = FoldOrOfICmps(LHS, RHS, &I))
return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
// If this is or(cast(fcmp), cast(fcmp)), try to fold this even if the
// cast is otherwise not optimizable. This happens for vector sexts.
if (FCmpInst *RHS = dyn_cast<FCmpInst>(Op1COp))
if (FCmpInst *LHS = dyn_cast<FCmpInst>(Op0COp))
if (Value *Res = FoldOrOfFCmps(LHS, RHS))
return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
}
}
}
// or(sext(A), B) -> A ? -1 : B where A is an i1
// or(A, sext(B)) -> B ? -1 : A where B is an i1
if (match(Op0, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1))
return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1);
if (match(Op1, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1))
return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0);
// Note: If we've gotten to the point of visiting the outer OR, then the
// inner one couldn't be simplified. If it was a constant, then it won't
// be simplified by a later pass either, so we try swapping the inner/outer
// ORs in the hopes that we'll be able to simplify it this way.
// (X|C) | V --> (X|V) | C
if (Op0->hasOneUse() && !isa<ConstantInt>(Op1) &&
match(Op0, m_Or(m_Value(A), m_ConstantInt(C1)))) {
Value *Inner = Builder->CreateOr(A, Op1);
Inner->takeName(Op0);
return BinaryOperator::CreateOr(Inner, C1);
}
// Change (or (bool?A:B),(bool?C:D)) --> (bool?(or A,C):(or B,D))
// Since this OR statement hasn't been optimized further yet, we hope
// that this transformation will allow the new ORs to be optimized.
{
Value *X = nullptr, *Y = nullptr;
if (Op0->hasOneUse() && Op1->hasOneUse() &&
match(Op0, m_Select(m_Value(X), m_Value(A), m_Value(B))) &&
match(Op1, m_Select(m_Value(Y), m_Value(C), m_Value(D))) && X == Y) {
Value *orTrue = Builder->CreateOr(A, C);
Value *orFalse = Builder->CreateOr(B, D);
return SelectInst::Create(X, orTrue, orFalse);
}
}
return Changed ? &I : nullptr;
}
Instruction *InstCombiner::visitXor(BinaryOperator &I) {
bool Changed = SimplifyAssociativeOrCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyVectorOp(I))
return ReplaceInstUsesWith(I, V);
if (Value *V = SimplifyXorInst(Op0, Op1, DL, TLI, DT, AC))
return ReplaceInstUsesWith(I, V);
// (A&B)^(A&C) -> A&(B^C) etc
if (Value *V = SimplifyUsingDistributiveLaws(I))
return ReplaceInstUsesWith(I, V);
// See if we can simplify any instructions used by the instruction whose sole
// purpose is to compute bits we don't care about.
if (SimplifyDemandedInstructionBits(I))
return &I;
if (Value *V = SimplifyBSwap(I))
return ReplaceInstUsesWith(I, V);
// Is this a ~ operation?
if (Value *NotOp = dyn_castNotVal(&I)) {
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
if (Op0I->getOpcode() == Instruction::And ||
Op0I->getOpcode() == Instruction::Or) {
// ~(~X & Y) --> (X | ~Y) - De Morgan's Law
// ~(~X | Y) === (X & ~Y) - De Morgan's Law
if (dyn_castNotVal(Op0I->getOperand(1)))
Op0I->swapOperands();
if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
Value *NotY =
Builder->CreateNot(Op0I->getOperand(1),
Op0I->getOperand(1)->getName()+".not");
if (Op0I->getOpcode() == Instruction::And)
return BinaryOperator::CreateOr(Op0NotVal, NotY);
return BinaryOperator::CreateAnd(Op0NotVal, NotY);
}
// ~(X & Y) --> (~X | ~Y) - De Morgan's Law
// ~(X | Y) === (~X & ~Y) - De Morgan's Law
if (IsFreeToInvert(Op0I->getOperand(0),
Op0I->getOperand(0)->hasOneUse()) &&
IsFreeToInvert(Op0I->getOperand(1),
Op0I->getOperand(1)->hasOneUse())) {
Value *NotX =
Builder->CreateNot(Op0I->getOperand(0), "notlhs");
Value *NotY =
Builder->CreateNot(Op0I->getOperand(1), "notrhs");
if (Op0I->getOpcode() == Instruction::And)
return BinaryOperator::CreateOr(NotX, NotY);
return BinaryOperator::CreateAnd(NotX, NotY);
}
} else if (Op0I->getOpcode() == Instruction::AShr) {
// ~(~X >>s Y) --> (X >>s Y)
if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0)))
return BinaryOperator::CreateAShr(Op0NotVal, Op0I->getOperand(1));
}
}
}
if (Constant *RHS = dyn_cast<Constant>(Op1)) {
if (RHS->isAllOnesValue() && Op0->hasOneUse())
// xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
if (CmpInst *CI = dyn_cast<CmpInst>(Op0))
return CmpInst::Create(CI->getOpcode(),
CI->getInversePredicate(),
CI->getOperand(0), CI->getOperand(1));
}
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
// fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {
if (CI->hasOneUse() && Op0C->hasOneUse()) {
Instruction::CastOps Opcode = Op0C->getOpcode();
if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) &&
(RHS == ConstantExpr::getCast(Opcode, Builder->getTrue(),
Op0C->getDestTy()))) {
CI->setPredicate(CI->getInversePredicate());
return CastInst::Create(Opcode, CI, Op0C->getType());
}
}
}
}
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
// ~(c-X) == X-c-1 == X+(-c-1)
if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
ConstantInt::get(I.getType(), 1));
return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS);
}
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
if (Op0I->getOpcode() == Instruction::Add) {
// ~(X-c) --> (-c-1)-X
if (RHS->isAllOnesValue()) {
Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
return BinaryOperator::CreateSub(
ConstantExpr::getSub(NegOp0CI,
ConstantInt::get(I.getType(), 1)),
Op0I->getOperand(0));
} else if (RHS->getValue().isSignBit()) {
// (X + C) ^ signbit -> (X + C + signbit)
Constant *C = Builder->getInt(RHS->getValue() + Op0CI->getValue());
return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
}
} else if (Op0I->getOpcode() == Instruction::Or) {
// (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue(),
0, &I)) {
Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
// Anything in both C1 and C2 is known to be zero, remove it from
// NewRHS.
Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS);
NewRHS = ConstantExpr::getAnd(NewRHS,
ConstantExpr::getNot(CommonBits));
Worklist.Add(Op0I);
I.setOperand(0, Op0I->getOperand(0));
I.setOperand(1, NewRHS);
return &I;
}
} else if (Op0I->getOpcode() == Instruction::LShr) {
// ((X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3)
// E1 = "X ^ C1"
BinaryOperator *E1;
ConstantInt *C1;
if (Op0I->hasOneUse() &&
(E1 = dyn_cast<BinaryOperator>(Op0I->getOperand(0))) &&
E1->getOpcode() == Instruction::Xor &&
(C1 = dyn_cast<ConstantInt>(E1->getOperand(1)))) {
// fold (C1 >> C2) ^ C3
ConstantInt *C2 = Op0CI, *C3 = RHS;
APInt FoldConst = C1->getValue().lshr(C2->getValue());
FoldConst ^= C3->getValue();
// Prepare the two operands.
Value *Opnd0 = Builder->CreateLShr(E1->getOperand(0), C2);
Opnd0->takeName(Op0I);
cast<Instruction>(Opnd0)->setDebugLoc(I.getDebugLoc());
Value *FoldVal = ConstantInt::get(Opnd0->getType(), FoldConst);
return BinaryOperator::CreateXor(Opnd0, FoldVal);
}
}
}
}
// Try to fold constant and into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldOpIntoSelect(I, SI))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
}
BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
if (Op1I) {
Value *A, *B;
if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
if (A == Op0) { // B^(B|A) == (A|B)^B
Op1I->swapOperands();
I.swapOperands();
std::swap(Op0, Op1);
} else if (B == Op0) { // B^(A|B) == (A|B)^B
I.swapOperands(); // Simplified below.
std::swap(Op0, Op1);
}
} else if (match(Op1I, m_And(m_Value(A), m_Value(B))) &&
Op1I->hasOneUse()){
if (A == Op0) { // A^(A&B) -> A^(B&A)
Op1I->swapOperands();
std::swap(A, B);
}
if (B == Op0) { // A^(B&A) -> (B&A)^A
I.swapOperands(); // Simplified below.
std::swap(Op0, Op1);
}
}
}
BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
if (Op0I) {
Value *A, *B;
if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
Op0I->hasOneUse()) {
if (A == Op1) // (B|A)^B == (A|B)^B
std::swap(A, B);
if (B == Op1) // (A|B)^B == A & ~B
return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1));
} else if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
Op0I->hasOneUse()){
if (A == Op1) // (A&B)^A -> (B&A)^A
std::swap(A, B);
if (B == Op1 && // (B&A)^A == ~B & A
!isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
return BinaryOperator::CreateAnd(Builder->CreateNot(A), Op1);
}
}
}
if (Op0I && Op1I) {
Value *A, *B, *C, *D;
// (A & B)^(A | B) -> A ^ B
if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
if ((A == C && B == D) || (A == D && B == C))
return BinaryOperator::CreateXor(A, B);
}
// (A | B)^(A & B) -> A ^ B
if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
match(Op1I, m_And(m_Value(C), m_Value(D)))) {
if ((A == C && B == D) || (A == D && B == C))
return BinaryOperator::CreateXor(A, B);
}
// (A | ~B) ^ (~A | B) -> A ^ B
if (match(Op0I, m_Or(m_Value(A), m_Not(m_Value(B)))) &&
match(Op1I, m_Or(m_Not(m_Specific(A)), m_Specific(B)))) {
return BinaryOperator::CreateXor(A, B);
}
// (~A | B) ^ (A | ~B) -> A ^ B
if (match(Op0I, m_Or(m_Not(m_Value(A)), m_Value(B))) &&
match(Op1I, m_Or(m_Specific(A), m_Not(m_Specific(B))))) {
return BinaryOperator::CreateXor(A, B);
}
// (A & ~B) ^ (~A & B) -> A ^ B
if (match(Op0I, m_And(m_Value(A), m_Not(m_Value(B)))) &&
match(Op1I, m_And(m_Not(m_Specific(A)), m_Specific(B)))) {
return BinaryOperator::CreateXor(A, B);
}
// (~A & B) ^ (A & ~B) -> A ^ B
if (match(Op0I, m_And(m_Not(m_Value(A)), m_Value(B))) &&
match(Op1I, m_And(m_Specific(A), m_Not(m_Specific(B))))) {
return BinaryOperator::CreateXor(A, B);
}
// (A ^ C)^(A | B) -> ((~A) & B) ^ C
if (match(Op0I, m_Xor(m_Value(D), m_Value(C))) &&
match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
if (D == A)
return BinaryOperator::CreateXor(
Builder->CreateAnd(Builder->CreateNot(A), B), C);
if (D == B)
return BinaryOperator::CreateXor(
Builder->CreateAnd(Builder->CreateNot(B), A), C);
}
// (A | B)^(A ^ C) -> ((~A) & B) ^ C
if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
match(Op1I, m_Xor(m_Value(D), m_Value(C)))) {
if (D == A)
return BinaryOperator::CreateXor(
Builder->CreateAnd(Builder->CreateNot(A), B), C);
if (D == B)
return BinaryOperator::CreateXor(
Builder->CreateAnd(Builder->CreateNot(B), A), C);
}
// (A & B) ^ (A ^ B) -> (A | B)
if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
match(Op1I, m_Xor(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateOr(A, B);
// (A ^ B) ^ (A & B) -> (A | B)
if (match(Op0I, m_Xor(m_Value(A), m_Value(B))) &&
match(Op1I, m_And(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateOr(A, B);
}
Value *A = nullptr, *B = nullptr;
// (A & ~B) ^ (~A) -> ~(A & B)
if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) &&
match(Op1, m_Not(m_Specific(A))))
return BinaryOperator::CreateNot(Builder->CreateAnd(A, B));
// (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
if (PredicatesFoldable(LHS->getPredicate(), RHS->getPredicate())) {
if (LHS->getOperand(0) == RHS->getOperand(1) &&
LHS->getOperand(1) == RHS->getOperand(0))
LHS->swapOperands();
if (LHS->getOperand(0) == RHS->getOperand(0) &&
LHS->getOperand(1) == RHS->getOperand(1)) {
Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS);
bool isSigned = LHS->isSigned() || RHS->isSigned();
return ReplaceInstUsesWith(I,
getNewICmpValue(isSigned, Code, Op0, Op1,
Builder));
}
}
// fold (xor (cast A), (cast B)) -> (cast (xor A, B))
if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
Type *SrcTy = Op0C->getOperand(0)->getType();
if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntegerTy() &&
// Only do this if the casts both really cause code to be generated.
ShouldOptimizeCast(Op0C->getOpcode(), Op0C->getOperand(0),
I.getType()) &&
ShouldOptimizeCast(Op1C->getOpcode(), Op1C->getOperand(0),
I.getType())) {
Value *NewOp = Builder->CreateXor(Op0C->getOperand(0),
Op1C->getOperand(0), I.getName());
return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
}
}
}
return Changed ? &I : nullptr;
}