diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp | 24 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/demorgan.ll | 9 |
2 files changed, 17 insertions, 16 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp index e37ceb58f15..41ae37ee127 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -2438,16 +2438,20 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) { if (match(&I, m_Not(m_BinOp(NotOp)))) { if (NotOp->getOpcode() == Instruction::And || NotOp->getOpcode() == Instruction::Or) { - // ~(~X & Y) --> (X | ~Y) - De Morgan's Law - // ~(~X | Y) === (X & ~Y) - De Morgan's Law - if (dyn_castNotVal(NotOp->getOperand(1))) - NotOp->swapOperands(); - if (Value *Op0NotVal = dyn_castNotVal(NotOp->getOperand(0))) { - Value *NotY = Builder->CreateNot( - NotOp->getOperand(1), NotOp->getOperand(1)->getName() + ".not"); - if (NotOp->getOpcode() == Instruction::And) - return BinaryOperator::CreateOr(Op0NotVal, NotY); - return BinaryOperator::CreateAnd(Op0NotVal, NotY); + // We must eliminate the and/or for this transform to not increase the + // instruction count. + if (NotOp->hasOneUse()) { + // ~(~X & Y) --> (X | ~Y) - De Morgan's Law + // ~(~X | Y) === (X & ~Y) - De Morgan's Law + if (dyn_castNotVal(NotOp->getOperand(1))) + NotOp->swapOperands(); + if (Value *Op0NotVal = dyn_castNotVal(NotOp->getOperand(0))) { + Value *NotY = Builder->CreateNot( + NotOp->getOperand(1), NotOp->getOperand(1)->getName() + ".not"); + if (NotOp->getOpcode() == Instruction::And) + return BinaryOperator::CreateOr(Op0NotVal, NotY); + return BinaryOperator::CreateAnd(Op0NotVal, NotY); + } } // ~(X & Y) --> (~X | ~Y) - De Morgan's Law diff --git a/llvm/test/Transforms/InstCombine/demorgan.ll b/llvm/test/Transforms/InstCombine/demorgan.ll index d98dddb9275..fc4af3c6dad 100644 --- a/llvm/test/Transforms/InstCombine/demorgan.ll +++ b/llvm/test/Transforms/InstCombine/demorgan.ll @@ -286,8 +286,7 @@ define i8 @demorgan_nor_use2c(i8 %A, i8 %B) { ; CHECK-NEXT: [[NOTA:%.*]] = xor i8 %A, -1 ; CHECK-NEXT: [[C:%.*]] = or i8 [[NOTA]], %B ; CHECK-NEXT: [[USE2C:%.*]] = mul i8 [[C]], 23 -; CHECK-NEXT: [[B_NOT:%.*]] = xor i8 %B, -1 -; CHECK-NEXT: [[NOTC:%.*]] = and i8 [[B_NOT]], %A +; CHECK-NEXT: [[NOTC:%.*]] = xor i8 [[C]], -1 ; CHECK-NEXT: [[R:%.*]] = sdiv i8 [[NOTC]], [[USE2C]] ; CHECK-NEXT: ret i8 [[R]] ; @@ -330,8 +329,7 @@ define i8 @demorgan_nor_use2ac(i8 %A, i8 %B) { ; CHECK-NEXT: [[USE2A:%.*]] = mul i8 [[NOTA]], 17 ; CHECK-NEXT: [[C:%.*]] = or i8 [[NOTA]], %B ; CHECK-NEXT: [[USE2C:%.*]] = mul i8 [[C]], 23 -; CHECK-NEXT: [[B_NOT:%.*]] = xor i8 %B, -1 -; CHECK-NEXT: [[NOTC:%.*]] = and i8 [[B_NOT]], %A +; CHECK-NEXT: [[NOTC:%.*]] = xor i8 [[C]], -1 ; CHECK-NEXT: [[R1:%.*]] = sdiv i8 [[NOTC]], [[USE2C]] ; CHECK-NEXT: [[R2:%.*]] = sdiv i8 [[R1]], [[USE2A]] ; CHECK-NEXT: ret i8 [[R2]] @@ -354,8 +352,7 @@ define i8 @demorgan_nor_use2bc(i8 %A, i8 %B) { ; CHECK-NEXT: [[NOTA:%.*]] = xor i8 %A, -1 ; CHECK-NEXT: [[C:%.*]] = or i8 [[NOTA]], %B ; CHECK-NEXT: [[USE2C:%.*]] = mul i8 [[C]], 23 -; CHECK-NEXT: [[B_NOT:%.*]] = xor i8 %B, -1 -; CHECK-NEXT: [[NOTC:%.*]] = and i8 [[B_NOT]], %A +; CHECK-NEXT: [[NOTC:%.*]] = xor i8 [[C]], -1 ; CHECK-NEXT: [[R1:%.*]] = sdiv i8 [[NOTC]], [[USE2C]] ; CHECK-NEXT: [[R2:%.*]] = sdiv i8 [[R1]], [[USE2B]] ; CHECK-NEXT: ret i8 [[R2]] |
