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| author | Nick Lewycky <nicholas@mxc.ca> | 2008-08-17 19:58:24 +0000 |
|---|---|---|
| committer | Nick Lewycky <nicholas@mxc.ca> | 2008-08-17 19:58:24 +0000 |
| commit | 53b44029d663b57ddac9a042a9c04fad7762442f (patch) | |
| tree | 90d9f4204f41b4ddeff0d2a1f69ea7e8f87afcae /llvm/lib | |
| parent | f37daa50dae04e34c34711fba2357e39f74d19a7 (diff) | |
| download | bcm5719-llvm-53b44029d663b57ddac9a042a9c04fad7762442f.tar.gz bcm5719-llvm-53b44029d663b57ddac9a042a9c04fad7762442f.zip | |
Consider the case where xor by -1 and xor by 128 have been combined already to
produce an xor by 127.
llvm-svn: 54906
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/InstructionCombining.cpp | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp index 32232a65889..defad26f8a1 100644 --- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp @@ -5503,8 +5503,8 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { return new ICmpInst(I.getPredicate(), Op0I->getOperand(0), Op1I->getOperand(0)); } else { - // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) { + // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b if (CI->getValue().isSignBit()) { ICmpInst::Predicate Pred = I.isSignedPredicate() ? I.getUnsignedPredicate() @@ -5512,6 +5512,17 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { return new ICmpInst(Pred, Op0I->getOperand(0), Op1I->getOperand(0)); } + + // icmp u/s (a ^ ~signbit), (b ^ ~signbit) --> icmp s/u b, a + if ((~CI->getValue()).isSignBit()) { + ICmpInst::Predicate Pred = I.isSignedPredicate() + ? I.getUnsignedPredicate() + : I.getSignedPredicate(); + Pred = I.getSwappedPredicate(Pred); + return new ICmpInst(Pred, Op0I->getOperand(0), + Op1I->getOperand(0)); + + } } } break; @@ -5818,6 +5829,17 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, return new ICmpInst(Pred, LHSI->getOperand(0), ConstantInt::get(RHSV ^ SignBit)); } + + // (icmp u/s (xor A ~SignBit), C) -> (icmp ~s/u A, (xor C ~SignBit)) + if (!ICI.isEquality() && (~XorCST->getValue()).isSignBit()) { + const APInt &NotSignBit = XorCST->getValue(); + ICmpInst::Predicate Pred = ICI.isSignedPredicate() + ? ICI.getUnsignedPredicate() + : ICI.getSignedPredicate(); + Pred = ICI.getSwappedPredicate(Pred); + return new ICmpInst(Pred, LHSI->getOperand(0), + ConstantInt::get(RHSV ^ NotSignBit)); + } } break; case Instruction::And: // (icmp pred (and X, AndCST), RHS) |
