Changes in directory llvm/lib/Transforms/Scalar:
InstructionCombining.cpp updated: 1.770 -> 1.771 --- Log message: Implement two xforms: 1. ~(~X | Y) === (X & ~Y) 2. (A|B) & ~(A&B) -> A^B This allows us to transform ~(~(a|b) | (a&b)) -> a^b. This implements PR1510: http://llvm.org/PR1510 for scalar values. --- Diffs of the changes: (+26 -6) InstructionCombining.cpp | 32 ++++++++++++++++++++++++++------ 1 files changed, 26 insertions(+), 6 deletions(-) Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.770 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.771 --- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.770 Fri Jun 15 00:26:55 2007 +++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp Fri Jun 15 00:58:24 2007 @@ -3363,13 +3363,28 @@ } { - Value *A = 0, *B = 0; - if (match(Op0, m_Or(m_Value(A), m_Value(B)))) + Value *A = 0, *B = 0, *C = 0, *D = 0; + if (match(Op0, m_Or(m_Value(A), m_Value(B)))) { if (A == Op1 || B == Op1) // (A | ?) & A --> A return ReplaceInstUsesWith(I, Op1); - if (match(Op1, m_Or(m_Value(A), m_Value(B)))) + + // (A|B) & ~(A&B) -> A^B + if (match(Op1, m_Not(m_And(m_Value(C), m_Value(D))))) { + if ((A == C && B == D) || (A == D && B == C)) + return BinaryOperator::createXor(A, B); + } + } + + if (match(Op1, m_Or(m_Value(A), m_Value(B)))) { if (A == Op0 || B == Op0) // A & (A | ?) --> A return ReplaceInstUsesWith(I, Op0); + + // ~(A&B) & (A|B) -> A^B + if (match(Op0, m_Not(m_And(m_Value(C), m_Value(D))))) { + if ((A == C && B == D) || (A == D && B == C)) + return BinaryOperator::createXor(A, B); + } + } if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_Value(B)))) { @@ -4137,15 +4152,20 @@ return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS); } - // ~(~X & Y) --> (X | ~Y) - if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) { + // ~(~X & Y) --> (X | ~Y) - De Morgan's Law + // ~(~X | Y) === (X & ~Y) - De Morgan's Law + if ((Op0I->getOpcode() == Instruction::And || + Op0I->getOpcode() == Instruction::Or) && RHS->isAllOnesValue()) { if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands(); if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) { Instruction *NotY = BinaryOperator::createNot(Op0I->getOperand(1), Op0I->getOperand(1)->getName()+".not"); InsertNewInstBefore(NotY, I); - return BinaryOperator::createOr(Op0NotVal, NotY); + if (Op0I->getOpcode() == Instruction::And) + return BinaryOperator::createOr(Op0NotVal, NotY); + else + return BinaryOperator::createAnd(Op0NotVal, NotY); } } _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
