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Oops, wasn't intending to commit this. Partial revert of r132194. 

llvm-svn: 132195
This commit is contained in:
Eli Friedman 2011-05-27 18:04:04 +00:00
parent fe84bd659c
commit b868c83e67
1 changed files with 9 additions and 6 deletions
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15
llvm/lib/Transforms/Scalar/LICM.cpp
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@ -372,11 +372,7 @@ bool LICM::canSinkOrHoistInst(Instruction &I) {
return !pointerInvalidatedByLoop(LI->getOperand(0), Size,
LI->getMetadata(LLVMContext::MD_tbaa));
} else if (CallInst *CI = dyn_cast<CallInst>(&I)) {
// Don't sink or hoist dbg info; it's legal, but not useful.
if (isa<DbgInfoIntrinsic>(I))
return false;
// Handle simple cases by querying alias analysis.
// Handle obvious cases efficiently.
AliasAnalysis::ModRefBehavior Behavior = AA->getModRefBehavior(CI);
if (Behavior == AliasAnalysis::DoesNotAccessMemory)
return true;
@ -526,7 +522,14 @@ void LICM::sink(Instruction &I) {
SSA.AddAvailableValue(ExitBlock, New);
}
assert(NumInserted && "We shouldn't see dead instructions here!");
// If the instruction doesn't dominate any exit blocks, it must be dead.
if (NumInserted == 0) {
CurAST->deleteValue(&I);
if (!I.use_empty())
I.replaceAllUsesWith(UndefValue::get(I.getType()));
I.eraseFromParent();
return;
}
// Next, rewrite uses of the instruction, inserting PHI nodes as needed.
for (Value::use_iterator UI = I.use_begin(), UE = I.use_end(); UI != UE; ) {