[PATCH] D47345: [InstructionCombining] Replace small allocations with local/global variable

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


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Comment at: lib/Transforms/InstCombine/InstructionCombining.cpp:2299
+
+  if (LI->getLoopFor(Malloc->getParent())) {
+    // Do not optimize if malloc is in loop
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xbolva00 wrote:
> efriedma wrote:
> > This isn't sufficient to guarantee malloc will be called once; getLoopFor won't find irreducible loops.
> How can we fix it and detect them?
> 
> I read some comments about irreducible loops in getNearestLoop...
There's a helper containsIrreducibleCFG.


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Comment at: lib/Transforms/InstCombine/InstructionCombining.cpp:2276
+bool InstCombiner::eliminateSmallAllocations(Value *Op, CallInst &FI) {
+  static MapVector<Function *, unsigned> Eliminations;
+  Function *F = FI.getFunction();
----------------
You can't use a static variable like this; LLVM can run on multiple threads in a program at the same time.


https://reviews.llvm.org/D47345