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fold constantexprs more aggressively, fixing PR1265

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35336 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-03-25 05:47:04 +00:00
parent 7177c3a60a
commit 2ef14d9f7c
1 changed files with 17 additions and 2 deletions
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19
lib/VMCore/ConstantFold.cpp
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@ -519,10 +519,20 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
return Constant::getNullValue(CI->getType()); // X % 1 == 0
break;
case Instruction::And:
if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2))
if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) {
if (CI->isZero()) return const_cast<Constant*>(C2); // X & 0 == 0
if (CI->isAllOnesValue())
return const_cast<Constant*>(C1); // X & -1 == X
if (C2->isNullValue()) return const_cast<Constant*>(C2); // X & 0 == 0
// (zext i32 to i64) & 4294967295 -> (zext i32 to i64)
if (CE1->getOpcode() == Instruction::ZExt) {
APInt PossiblySetBits
= cast<IntegerType>(CE1->getOperand(0)->getType())->getMask();
PossiblySetBits.zext(C1->getType()->getPrimitiveSizeInBits());
if ((PossiblySetBits & CI->getValue()) == PossiblySetBits)
return const_cast<Constant*>(C1);
}
}
if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
@ -543,6 +553,11 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
case Instruction::Xor:
if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X
break;
case Instruction::AShr:
if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero.
return ConstantExpr::getLShr(const_cast<Constant*>(C1),
const_cast<Constant*>(C2));
break;
}
}
} else if (isa<ConstantExpr>(C2)) {