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Before promoting a malloc type, remove dead uses. This makes instcombine

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more effective at promoting these allocations, catching them earlier in the
compile process.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23959 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-10-24 06:22:12 +00:00
parent b3f8397a3d
commit b53c2382a9
1 changed files with 20 additions and 0 deletions
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20
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -3769,6 +3769,26 @@ Instruction *InstCombiner::PromoteCastOfAllocation(CastInst &CI,
const PointerType *PTy = dyn_cast<PointerType>(CI.getType());
if (AI.isArrayAllocation() || !PTy) return 0;
// Remove any uses of AI that are dead.
assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
std::vector<Instruction*> DeadUsers;
for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
Instruction *User = cast<Instruction>(*UI++);
if (isInstructionTriviallyDead(User)) {
while (UI != E && *UI == User)
++UI; // If this instruction uses AI more than once, don't break UI.
// Add operands to the worklist.
AddUsesToWorkList(*User);
++NumDeadInst;
DEBUG(std::cerr << "IC: DCE: " << *User);
User->eraseFromParent();
removeFromWorkList(User);
}
}
// Finally, if the instruction now has one use, delete it.
if (!AI.hasOneUse()) return 0;
// Get the type really allocated and the type casted to.