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Small improvement: if a function doesn't access memory, we don't need to scan

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it for potentially undeading pointers.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40933 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2007-08-08 17:58:56 +00:00
parent bb3abf41a8
commit df359c264e
1 changed files with 8 additions and 2 deletions
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10
lib/Transforms/Scalar/DeadStoreElimination.cpp
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@ -287,6 +287,13 @@ bool DSE::handleEndBlock(BasicBlock& BB,
deadPointers.erase(A); deadPointers.erase(A);
continue; continue;
} else if (CallSite::get(BBI).getInstruction() != 0) { } else if (CallSite::get(BBI).getInstruction() != 0) {
// If this call does not access memory, it can't
// be undeadifying any of our pointers.
CallSite CS = CallSite::get(BBI);
if (CS.getCalledFunction() &&
AA.doesNotAccessMemory(CS.getCalledFunction()))
continue;
// Remove any pointers made undead by the call from the dead set // Remove any pointers made undead by the call from the dead set
std::vector<Instruction*> dead; std::vector<Instruction*> dead;
for (SmallPtrSet<AllocaInst*, 64>::iterator I = deadPointers.begin(), for (SmallPtrSet<AllocaInst*, 64>::iterator I = deadPointers.begin(),
@ -298,8 +305,7 @@ bool DSE::handleEndBlock(BasicBlock& BB,
TD.getTypeSize((*I)->getAllocatedType()); TD.getTypeSize((*I)->getAllocatedType());
// See if the call site touches it // See if the call site touches it
AliasAnalysis::ModRefResult A = AA.getModRefInfo(CallSite::get(BBI), AliasAnalysis::ModRefResult A = AA.getModRefInfo(CS, *I, pointerSize);
*I, pointerSize);
if (A == AliasAnalysis::ModRef || A == AliasAnalysis::Ref) if (A == AliasAnalysis::ModRef || A == AliasAnalysis::Ref)
dead.push_back(*I); dead.push_back(*I);
} }