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IC: (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)

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Minor code cleanup


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7262 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-07-23 17:57:01 +00:00
parent 2b8e478b5d
commit c6a8aff3f6
1 changed files with 16 additions and 4 deletions
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20
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -493,19 +493,31 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
return ReplaceInstUsesWith(I, Op1);
// and X, -1 == X
if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1))
if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
if (RHS->isAllOnesValue())
return ReplaceInstUsesWith(I, Op0);
// (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
if (Op0I->getOpcode() == Instruction::Xor && isOnlyUse(Op0))
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
std::string Op0Name = Op0I->getName(); Op0I->setName("");
Instruction *And = BinaryOperator::create(Instruction::And,
Op0I->getOperand(0), RHS,
Op0Name);
InsertNewInstBefore(And, I);
return BinaryOperator::create(Instruction::Xor, And, *RHS & *Op0CI);
}
}
Value *Op0NotVal = dyn_castNotVal(Op0);
Value *Op1NotVal = dyn_castNotVal(Op1);
// (~A & ~B) == (~(A | B)) - Demorgan's Law
if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
Instruction *Or = BinaryOperator::create(Instruction::Or, Op0NotVal,
Op1NotVal,I.getName()+".demorgan",
&I);
WorkList.push_back(Or);
Op1NotVal,I.getName()+".demorgan");
InsertNewInstBefore(Or, I);
return BinaryOperator::createNot(Or);
}