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

llvm-svn: 9711
This commit is contained in:
Chris Lattner 2003-11-04 23:50:51 +00:00
parent f6368c803c
commit e580666532
1 changed files with 17 additions and 3 deletions
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20
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1001,22 +1001,36 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
return new SetCondInst(SCI->getInverseCondition(), return new SetCondInst(SCI->getInverseCondition(),
SCI->getOperand(0), SCI->getOperand(1)); 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 (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
if (Op0I->getOpcode() == Instruction::Add) { switch (Op0I->getOpcode()) {
case Instruction::Add:
// ~(X-c) --> (-c-1)-X // ~(X-c) --> (-c-1)-X
if (RHS->isAllOnesValue()) if (RHS->isAllOnesValue())
return BinaryOperator::create(Instruction::Sub, return BinaryOperator::create(Instruction::Sub,
*-*Op0CI - *-*Op0CI -
*ConstantInt::get(I.getType(), 1), *ConstantInt::get(I.getType(), 1),
Op0I->getOperand(0)); Op0I->getOperand(0));
} else if (Op0I->getOpcode() == Instruction::And) { break;
case Instruction::And:
// (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
if ((*RHS & *Op0CI)->isNullValue()) if ((*RHS & *Op0CI)->isNullValue())
return BinaryOperator::create(Instruction::Or, Op0, RHS); 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 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
if ((*RHS & *Op0CI) == RHS) if ((*RHS & *Op0CI) == RHS)
return BinaryOperator::create(Instruction::And, Op0, ~*RHS); return BinaryOperator::create(Instruction::And, Op0, ~*RHS);
break;
default: break;
} }
} }
} }