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InstCombine: (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7272 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-07-23 19:36:21 +00:00
parent 4daaebf170
commit 06782f804f
1 changed files with 11 additions and 9 deletions
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20
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -497,23 +497,25 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
if (RHS->isAllOnesValue())
return ReplaceInstUsesWith(I, Op0);
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
Value *X = Op0I->getOperand(0);
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
if (Op0I->getOpcode() == Instruction::Xor) {
if (isOnlyUse(Op0)) {
if ((*RHS & *Op0CI)->isNullValue()) {
// (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
return BinaryOperator::create(Instruction::And, X, RHS);
} else if (isOnlyUse(Op0)) {
// (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
std::string Op0Name = Op0I->getName(); Op0I->setName("");
Instruction *And = BinaryOperator::create(Instruction::And,
Op0I->getOperand(0), RHS,
Op0Name);
X, RHS, Op0Name);
InsertNewInstBefore(And, I);
return BinaryOperator::create(Instruction::Xor, And, *RHS & *Op0CI);
}
} else if (Op0I->getOpcode() == Instruction::Or) {
// (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
if ((*RHS & *Op0CI)->isNullValue())
return BinaryOperator::create(Instruction::And, Op0I->getOperand(0),
RHS);
return BinaryOperator::create(Instruction::And, X, RHS);
Constant *Together = *RHS & *Op0CI;
if (Together == RHS) // (X | C) & C --> C
@ -523,14 +525,14 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
if (Together != Op0CI) {
// (X | C1) & C2 --> (X | (C1&C2)) & C2
std::string Op0Name = Op0I->getName(); Op0I->setName("");
Instruction *Or = BinaryOperator::create(Instruction::Or,
Op0I->getOperand(0),
Together, Op0Name);
Instruction *Or = BinaryOperator::create(Instruction::Or, X,
Together, Op0Name);
InsertNewInstBefore(Or, I);
return BinaryOperator::create(Instruction::And, Or, RHS);
}
}
}
}
}
Value *Op0NotVal = dyn_castNotVal(Op0);