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simplify (x+c)^signbit as (x+c+signbit), pointed out by PR1288. This implements

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test/Transforms/InstCombine/xor.ll:test28


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35584 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-04-02 05:36:22 +00:00
parent 7a32bc9b9b
commit 5c6e2db0c4
1 changed files with 7 additions and 1 deletions
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8
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -4005,7 +4005,7 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
return BinaryOperator::createOr(Op0NotVal, NotY); return BinaryOperator::createOr(Op0NotVal, NotY);
} }
} }
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
if (Op0I->getOpcode() == Instruction::Add) { if (Op0I->getOpcode() == Instruction::Add) {
// ~(X-c) --> (-c-1)-X // ~(X-c) --> (-c-1)-X
@ -4015,6 +4015,12 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
ConstantExpr::getSub(NegOp0CI, ConstantExpr::getSub(NegOp0CI,
ConstantInt::get(I.getType(), 1)), ConstantInt::get(I.getType(), 1)),
Op0I->getOperand(0)); Op0I->getOperand(0));
} else if (RHS->getValue().isMinSignedValue()) {
// (X + C) ^ signbit -> (X + C + signbit)
Constant *C = ConstantInt::get(RHS->getValue() + Op0CI->getValue());
return BinaryOperator::createAdd(Op0I->getOperand(0), C);
} }
} else if (Op0I->getOpcode() == Instruction::Or) { } else if (Op0I->getOpcode() == Instruction::Or) {
// (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0 // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0