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Minor cleanup, plus implement InstCombine/xor.ll:test17

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9711 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-11-04 23:50:51 +00:00
parent 519c6965f5
commit ad5b4fb6b7
1 changed files with 17 additions and 3 deletions
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20
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1000,23 +1000,37 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
if (RHS == ConstantBool::True && SCI->hasOneUse())
return new SetCondInst(SCI->getInverseCondition(),
SCI->getOperand(0), SCI->getOperand(1));
// ~(c-X) == X-(c-1) == X+(-c+1)
if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue() &&
isa<Constant>(Op0I->getOperand(0))) {
Constant *ConstantRHS = *-*cast<Constant>(Op0I->getOperand(0)) +
*ConstantInt::get(I.getType(), 1);
return BinaryOperator::create(Instruction::Add, Op0I->getOperand(1),
ConstantRHS);
}
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
if (Op0I->getOpcode() == Instruction::Add) {
switch (Op0I->getOpcode()) {
case Instruction::Add:
// ~(X-c) --> (-c-1)-X
if (RHS->isAllOnesValue())
return BinaryOperator::create(Instruction::Sub,
*-*Op0CI -
*ConstantInt::get(I.getType(), 1),
Op0I->getOperand(0));
} else if (Op0I->getOpcode() == Instruction::And) {
break;
case Instruction::And:
// (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
if ((*RHS & *Op0CI)->isNullValue())
return BinaryOperator::create(Instruction::Or, Op0, RHS);
} else if (Op0I->getOpcode() == Instruction::Or) {
break;
case Instruction::Or:
// (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
if ((*RHS & *Op0CI) == RHS)
return BinaryOperator::create(Instruction::And, Op0, ~*RHS);
break;
default: break;
}
}
}