[PATCH] Fix a performance problem in gep(gep ...) merging

[Quentin Colombet]

Hi Wei,

What performance numbers do you have to back up your change?

Now the optimization looks too conservative too me. I may be wrong, but I would like to see evidences of that.

Thanks,
-Quentin


REPOSITORY
  rL LLVM

================
Comment at: lib/Transforms/InstCombine/InstructionCombining.cpp:1473
@@ +1472,3 @@
+        // before.
+        if (!isa<Constant>(GO1) || !isa<Constant>(SO1))
+          return nullptr;
----------------
This seems too conservative. In particular, in your comment you had mentioned the number of users.
What does a heuristic based on that give?

http://reviews.llvm.org/D8911

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