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ConstantFold: Clean up X * undef code

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No functional change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223970 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2014-12-10 21:58:17 +00:00
parent 72c6bdbf70
commit 3e04c3e253
1 changed files with 8 additions and 6 deletions
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14
lib/IR/ConstantFold.cpp
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@ -915,12 +915,14 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
return C1;
return Constant::getNullValue(C1->getType()); // undef & X -> 0
case Instruction::Mul: {
ConstantInt *CI;
// X * undef -> undef if X is odd or undef
if (((CI = dyn_cast<ConstantInt>(C1)) && CI->getValue()[0]) ||
((CI = dyn_cast<ConstantInt>(C2)) && CI->getValue()[0]) ||
(isa<UndefValue>(C1) && isa<UndefValue>(C2)))
return UndefValue::get(C1->getType());
// undef * undef -> undef
if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
return C1;
const APInt *CV;
// X * undef -> undef if X is odd
if (match(C1, m_APInt(CV)) || match(C2, m_APInt(CV)))
if ((*CV)[0])
return UndefValue::get(C1->getType());
// X * undef -> 0 otherwise
return Constant::getNullValue(C1->getType());