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author | Dimitry Andric <dim@FreeBSD.org> | 2017-07-19 07:02:10 +0000 |
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committer | Dimitry Andric <dim@FreeBSD.org> | 2017-07-19 07:02:10 +0000 |
commit | 93c91e39b29142dec1d03a30df9f6e757f56c193 (patch) | |
tree | 33a9b014a327e64450b3c9ed46d8c5bdb78ad345 /lib/Transforms/InstCombine/InstCombineCompares.cpp | |
parent | ca089b24d48ef6fa8da2d0bb8c25bb802c4a95c0 (diff) | |
download | src-93c91e39b29142dec1d03a30df9f6e757f56c193.tar.gz src-93c91e39b29142dec1d03a30df9f6e757f56c193.zip |
Vendor import of llvm trunk r308421:vendor/llvm/llvm-trunk-r308421
Notes
Notes:
svn path=/vendor/llvm/dist/; revision=321184
svn path=/vendor/llvm/llvm-trunk-r308421/; revision=321185; tag=vendor/llvm/llvm-trunk-r308421
Diffstat (limited to 'lib/Transforms/InstCombine/InstCombineCompares.cpp')
-rw-r--r-- | lib/Transforms/InstCombine/InstCombineCompares.cpp | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 60d1cde971dd..a8faaecb5c34 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -1814,9 +1814,21 @@ Instruction *InstCombiner::foldICmpOrConstant(ICmpInst &Cmp, BinaryOperator *Or, Builder.CreateICmp(Pred, P, ConstantInt::getNullValue(P->getType())); Value *CmpQ = Builder.CreateICmp(Pred, Q, ConstantInt::getNullValue(Q->getType())); - auto LogicOpc = Pred == ICmpInst::Predicate::ICMP_EQ ? Instruction::And - : Instruction::Or; - return BinaryOperator::Create(LogicOpc, CmpP, CmpQ); + auto BOpc = Pred == CmpInst::ICMP_EQ ? Instruction::And : Instruction::Or; + return BinaryOperator::Create(BOpc, CmpP, CmpQ); + } + + // Are we using xors to bitwise check for a pair of (in)equalities? Convert to + // a shorter form that has more potential to be folded even further. + Value *X1, *X2, *X3, *X4; + if (match(Or->getOperand(0), m_OneUse(m_Xor(m_Value(X1), m_Value(X2)))) && + match(Or->getOperand(1), m_OneUse(m_Xor(m_Value(X3), m_Value(X4))))) { + // ((X1 ^ X2) || (X3 ^ X4)) == 0 --> (X1 == X2) && (X3 == X4) + // ((X1 ^ X2) || (X3 ^ X4)) != 0 --> (X1 != X2) || (X3 != X4) + Value *Cmp12 = Builder.CreateICmp(Pred, X1, X2); + Value *Cmp34 = Builder.CreateICmp(Pred, X3, X4); + auto BOpc = Pred == CmpInst::ICMP_EQ ? Instruction::And : Instruction::Or; + return BinaryOperator::Create(BOpc, Cmp12, Cmp34); } return nullptr; @@ -3737,6 +3749,11 @@ static Instruction *processUMulZExtIdiom(ICmpInst &I, Value *MulVal, const APInt &CVal = CI->getValue(); if (CVal.getBitWidth() - CVal.countLeadingZeros() > MulWidth) return nullptr; + } else { + // In this case we could have the operand of the binary operation + // being defined in another block, and performing the replacement + // could break the dominance relation. + return nullptr; } } else { // Other uses prohibit this transformation. @@ -3856,18 +3873,17 @@ static Instruction *processUMulZExtIdiom(ICmpInst &I, Value *MulVal, } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) { assert(BO->getOpcode() == Instruction::And); // Replace (mul & mask) --> zext (mul.with.overflow & short_mask) - Value *ShortMask = - Builder.CreateTrunc(BO->getOperand(1), Builder.getIntNTy(MulWidth)); + ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1)); + APInt ShortMask = CI->getValue().trunc(MulWidth); Value *ShortAnd = Builder.CreateAnd(Mul, ShortMask); - Value *Zext = Builder.CreateZExt(ShortAnd, BO->getType()); - if (auto *ZextI = dyn_cast<Instruction>(Zext)) - IC.Worklist.Add(ZextI); + Instruction *Zext = + cast<Instruction>(Builder.CreateZExt(ShortAnd, BO->getType())); + IC.Worklist.Add(Zext); IC.replaceInstUsesWith(*BO, Zext); } else { llvm_unreachable("Unexpected Binary operation"); } - if (auto *UI = dyn_cast<Instruction>(U)) - IC.Worklist.Add(UI); + IC.Worklist.Add(cast<Instruction>(U)); } } if (isa<Instruction>(OtherVal)) |