mirror of
https://github.com/RPCS3/llvm-mirror.git
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[InstCombine] break up foldICmpEqualityWithConstant(); NFCI
Almost all of these folds require changes to allow vector types. Splitting up the logic should make that easier to do incrementally. llvm-svn: 276360
This commit is contained in:
Sanjay Patel
parent
9d63784d14
commit
f1b3404e72
@ -2204,7 +2204,8 @@ Instruction *InstCombiner::foldICmpWithConstant(ICmpInst &ICI,
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Instruction *InstCombiner::foldICmpEqualityWithConstant(ICmpInst &ICI,
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Instruction *LHSI,
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ConstantInt *RHS) {
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if (!ICI.isEquality())
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BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI);
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if (!BO || !ICI.isEquality())
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return nullptr;
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const APInt &RHSV = RHS->getValue();
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@ -2212,168 +2213,176 @@ Instruction *InstCombiner::foldICmpEqualityWithConstant(ICmpInst &ICI,
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// If the first operand is (add|sub|and|or|xor|rem) with a constant, and
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// the second operand is a constant, simplify a bit.
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if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
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switch (BO->getOpcode()) {
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case Instruction::SRem:
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// If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
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if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) && BO->hasOneUse()) {
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const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
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if (V.sgt(1) && V.isPowerOf2()) {
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Value *NewRem = Builder->CreateURem(BO->getOperand(0),
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BO->getOperand(1), BO->getName());
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return new ICmpInst(ICI.getPredicate(), NewRem,
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Constant::getNullValue(BO->getType()));
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}
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switch (BO->getOpcode()) {
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case Instruction::SRem:
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// If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
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if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) && BO->hasOneUse()) {
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const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
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if (V.sgt(1) && V.isPowerOf2()) {
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Value *NewRem = Builder->CreateURem(BO->getOperand(0),
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BO->getOperand(1), BO->getName());
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return new ICmpInst(ICI.getPredicate(), NewRem,
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Constant::getNullValue(BO->getType()));
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}
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break;
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case Instruction::Add:
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// Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
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if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
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if (BO->hasOneUse())
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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ConstantExpr::getSub(RHS, BOp1C));
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} else if (RHSV == 0) {
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// Replace ((add A, B) != 0) with (A != -B) if A or B is
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// efficiently invertible, or if the add has just this one use.
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Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
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if (Value *NegVal = dyn_castNegVal(BOp1))
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return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
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if (Value *NegVal = dyn_castNegVal(BOp0))
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return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
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if (BO->hasOneUse()) {
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Value *Neg = Builder->CreateNeg(BOp1);
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Neg->takeName(BO);
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return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
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}
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}
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break;
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case Instruction::Xor:
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if (BO->hasOneUse()) {
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if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
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// For the xor case, we can xor two constants together, eliminating
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// the explicit xor.
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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ConstantExpr::getXor(RHS, BOC));
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} else if (RHSV == 0) {
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// Replace ((xor A, B) != 0) with (A != B)
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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BO->getOperand(1));
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}
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}
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break;
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case Instruction::Sub:
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if (BO->hasOneUse()) {
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if (ConstantInt *BOp0C = dyn_cast<ConstantInt>(BO->getOperand(0))) {
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// Replace ((sub A, B) != C) with (B != A-C) if A & C are constants.
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(1),
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ConstantExpr::getSub(BOp0C, RHS));
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} else if (RHSV == 0) {
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// Replace ((sub A, B) != 0) with (A != B)
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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BO->getOperand(1));
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}
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}
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break;
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case Instruction::Or:
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// If bits are being or'd in that are not present in the constant we
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// are comparing against, then the comparison could never succeed!
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if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
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Constant *NotCI = ConstantExpr::getNot(RHS);
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if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
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return replaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
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// Comparing if all bits outside of a constant mask are set?
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// Replace (X | C) == -1 with (X & ~C) == ~C.
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// This removes the -1 constant.
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if (BO->hasOneUse() && RHS->isAllOnesValue()) {
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Constant *NotBOC = ConstantExpr::getNot(BOC);
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Value *And = Builder->CreateAnd(BO->getOperand(0), NotBOC);
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return new ICmpInst(ICI.getPredicate(), And, NotBOC);
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}
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}
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break;
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case Instruction::And:
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if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
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// If bits are being compared against that are and'd out, then the
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// comparison can never succeed!
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if ((RHSV & ~BOC->getValue()) != 0)
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return replaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
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// If we have ((X & C) == C), turn it into ((X & C) != 0).
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if (RHS == BOC && RHSV.isPowerOf2())
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return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
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LHSI, Constant::getNullValue(RHS->getType()));
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// Don't perform the following transforms if the AND has multiple uses
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if (!BO->hasOneUse())
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break;
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// Replace (and X, (1 << size(X)-1) != 0) with x s< 0
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if (BOC->getValue().isSignBit()) {
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Value *X = BO->getOperand(0);
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Constant *Zero = Constant::getNullValue(X->getType());
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ICmpInst::Predicate pred =
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isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
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return new ICmpInst(pred, X, Zero);
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}
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// ((X & ~7) == 0) --> X < 8
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if (RHSV == 0 && isHighOnes(BOC)) {
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Value *X = BO->getOperand(0);
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Constant *NegX = ConstantExpr::getNeg(BOC);
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ICmpInst::Predicate pred =
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isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
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return new ICmpInst(pred, X, NegX);
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}
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}
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break;
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case Instruction::Mul:
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if (RHSV == 0 && BO->hasNoSignedWrap()) {
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if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
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// The trivial case (mul X, 0) is handled by InstSimplify
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// General case : (mul X, C) != 0 iff X != 0
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// (mul X, C) == 0 iff X == 0
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if (!BOC->isZero())
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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Constant::getNullValue(RHS->getType()));
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}
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}
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break;
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default:
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break;
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}
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} else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
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// Handle icmp {eq|ne} <intrinsic>, intcst.
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switch (II->getIntrinsicID()) {
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case Intrinsic::bswap:
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break;
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case Instruction::Add:
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// Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
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if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
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if (BO->hasOneUse())
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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ConstantExpr::getSub(RHS, BOp1C));
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} else if (RHSV == 0) {
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// Replace ((add A, B) != 0) with (A != -B) if A or B is
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// efficiently invertible, or if the add has just this one use.
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Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
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if (Value *NegVal = dyn_castNegVal(BOp1))
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return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
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if (Value *NegVal = dyn_castNegVal(BOp0))
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return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
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if (BO->hasOneUse()) {
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Value *Neg = Builder->CreateNeg(BOp1);
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Neg->takeName(BO);
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return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
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}
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}
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break;
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case Instruction::Xor:
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if (BO->hasOneUse()) {
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if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
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// For the xor case, we can xor two constants together, eliminating
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// the explicit xor.
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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ConstantExpr::getXor(RHS, BOC));
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} else if (RHSV == 0) {
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// Replace ((xor A, B) != 0) with (A != B)
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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BO->getOperand(1));
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}
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}
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break;
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case Instruction::Sub:
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if (BO->hasOneUse()) {
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if (ConstantInt *BOp0C = dyn_cast<ConstantInt>(BO->getOperand(0))) {
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// Replace ((sub A, B) != C) with (B != A-C) if A & C are constants.
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(1),
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ConstantExpr::getSub(BOp0C, RHS));
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} else if (RHSV == 0) {
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// Replace ((sub A, B) != 0) with (A != B)
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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BO->getOperand(1));
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}
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}
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break;
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case Instruction::Or:
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// If bits are being or'd in that are not present in the constant we
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// are comparing against, then the comparison could never succeed!
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if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
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Constant *NotCI = ConstantExpr::getNot(RHS);
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if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
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return replaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
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// Comparing if all bits outside of a constant mask are set?
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// Replace (X | C) == -1 with (X & ~C) == ~C.
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// This removes the -1 constant.
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if (BO->hasOneUse() && RHS->isAllOnesValue()) {
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Constant *NotBOC = ConstantExpr::getNot(BOC);
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Value *And = Builder->CreateAnd(BO->getOperand(0), NotBOC);
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return new ICmpInst(ICI.getPredicate(), And, NotBOC);
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}
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}
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break;
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case Instruction::And:
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if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
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// If bits are being compared against that are and'd out, then the
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// comparison can never succeed!
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if ((RHSV & ~BOC->getValue()) != 0)
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return replaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
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// If we have ((X & C) == C), turn it into ((X & C) != 0).
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if (RHS == BOC && RHSV.isPowerOf2())
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return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
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LHSI, Constant::getNullValue(RHS->getType()));
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// Don't perform the following transforms if the AND has multiple uses
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if (!BO->hasOneUse())
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break;
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// Replace (and X, (1 << size(X)-1) != 0) with x s< 0
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if (BOC->getValue().isSignBit()) {
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Value *X = BO->getOperand(0);
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Constant *Zero = Constant::getNullValue(X->getType());
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ICmpInst::Predicate pred =
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isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
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return new ICmpInst(pred, X, Zero);
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}
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// ((X & ~7) == 0) --> X < 8
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if (RHSV == 0 && isHighOnes(BOC)) {
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Value *X = BO->getOperand(0);
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Constant *NegX = ConstantExpr::getNeg(BOC);
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ICmpInst::Predicate pred =
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isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
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return new ICmpInst(pred, X, NegX);
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}
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}
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break;
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case Instruction::Mul:
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if (RHSV == 0 && BO->hasNoSignedWrap()) {
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if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
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// The trivial case (mul X, 0) is handled by InstSimplify
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// General case : (mul X, C) != 0 iff X != 0
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// (mul X, C) == 0 iff X == 0
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if (!BOC->isZero())
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return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
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Constant::getNullValue(RHS->getType()));
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}
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}
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break;
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default:
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break;
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}
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return nullptr;
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}
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Instruction *InstCombiner::foldICmpIntrinsicWithConstant(ICmpInst &ICI,
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Instruction *LHSI,
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ConstantInt *RHS) {
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IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI);
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if (!II || !ICI.isEquality())
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return nullptr;
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// Handle icmp {eq|ne} <intrinsic>, intcst.
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const APInt &RHSV = RHS->getValue();
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switch (II->getIntrinsicID()) {
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case Intrinsic::bswap:
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Worklist.Add(II);
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ICI.setOperand(0, II->getArgOperand(0));
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ICI.setOperand(1, Builder->getInt(RHSV.byteSwap()));
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return &ICI;
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case Intrinsic::ctlz:
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case Intrinsic::cttz:
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// ctz(A) == bitwidth(a) -> A == 0 and likewise for !=
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if (RHSV == RHS->getType()->getBitWidth()) {
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Worklist.Add(II);
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ICI.setOperand(0, II->getArgOperand(0));
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ICI.setOperand(1, Builder->getInt(RHSV.byteSwap()));
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ICI.setOperand(1, ConstantInt::get(RHS->getType(), 0));
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return &ICI;
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case Intrinsic::ctlz:
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case Intrinsic::cttz:
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// ctz(A) == bitwidth(a) -> A == 0 and likewise for !=
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if (RHSV == RHS->getType()->getBitWidth()) {
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Worklist.Add(II);
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ICI.setOperand(0, II->getArgOperand(0));
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ICI.setOperand(1, ConstantInt::get(RHS->getType(), 0));
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return &ICI;
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}
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break;
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case Intrinsic::ctpop:
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// popcount(A) == 0 -> A == 0 and likewise for !=
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if (RHS->isZero()) {
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Worklist.Add(II);
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ICI.setOperand(0, II->getArgOperand(0));
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ICI.setOperand(1, RHS);
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return &ICI;
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}
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break;
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default:
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break;
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}
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break;
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case Intrinsic::ctpop:
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// popcount(A) == 0 -> A == 0 and likewise for !=
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if (RHS->isZero()) {
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Worklist.Add(II);
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ICI.setOperand(0, II->getArgOperand(0));
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ICI.setOperand(1, RHS);
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return &ICI;
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}
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break;
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default:
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break;
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}
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return nullptr;
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}
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@ -3634,6 +3643,8 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
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return Res;
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if (Instruction *Res = foldICmpEqualityWithConstant(I, LHSI, CI))
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return Res;
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if (Instruction *Res = foldICmpIntrinsicWithConstant(I, LHSI, CI))
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return Res;
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}
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// (icmp eq/ne (udiv A, B), 0) -> (icmp ugt/ule i32 B, A)
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if (I.isEquality() && CI->isZero() &&
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@ -585,6 +585,8 @@ private:
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ConstantInt *RHS);
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Instruction *foldICmpEqualityWithConstant(ICmpInst &ICI, Instruction *LHS,
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ConstantInt *RHS);
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Instruction *foldICmpIntrinsicWithConstant(ICmpInst &ICI, Instruction *LHS,
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ConstantInt *RHS);
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Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
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ConstantInt *AndRHS, BinaryOperator &TheAnd);
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