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Fast ISel trivially coalesces away no-op casts, so check for this when

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setting kill flags.

llvm-svn: 103832
This commit is contained in:
Dan Gohman 2010-05-14 22:53:18 +00:00
parent 7a16481068
commit 4049434a04
1 changed files with 16 additions and 4 deletions
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20
lib/CodeGen/SelectionDAG/FastISel.cpp
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@ -57,11 +57,23 @@
using namespace llvm;
bool FastISel::hasTrivialKill(const Value *V) const {
// Don't consider constants or arguments to have trivial kills. Only
// instructions with a single use in the same basic block.
// Don't consider constants or arguments to have trivial kills.
const Instruction *I = dyn_cast<Instruction>(V);
return I &&
I->hasOneUse() &&
if (!I)
return false;
// No-op casts are trivially coalesced by fast-isel.
if (const CastInst *Cast = dyn_cast<CastInst>(I))
if (Cast->isNoopCast(TD.getIntPtrType(Cast->getContext())) &&
!hasTrivialKill(Cast->getOperand(0)))
return false;
// Only instructions with a single use in the same basic block are considered
// to have trivial kills.
return I->hasOneUse() &&
!(I->getOpcode() == Instruction::BitCast ||
I->getOpcode() == Instruction::PtrToInt ||
I->getOpcode() == Instruction::IntToPtr) &&
cast<Instruction>(I->use_begin())->getParent() == I->getParent();
}