[all-commits] [llvm/llvm-project] 070af1: [InstCombine] avoid crashing on attribute propagation

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  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 070af1b7887f80383d8473bb4da565edbde6c6b0
      https://github.com/llvm/llvm-project/commit/070af1b7887f80383d8473bb4da565edbde6c6b0
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2021-01-21 (Thu, 21 Jan 2021)

  Changed paths:
    M llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
    M llvm/test/Transforms/InstCombine/mempcpy.ll

  Log Message:
  -----------
  [InstCombine] avoid crashing on attribute propagation

In https://llvm.org/PR48810 , we are crashing while trying to
propagate attributes from mempcpy (returns void*) to memcpy
(returns nothing - void).

We can avoid the crash by removing known incompatible
attributes for the void return type.

I'm not sure if this goes far enough (should we just drop all
attributes since this isn't the same function?). We also need
to audit other transforms in LibCallSimplifier to make sure
there are no other cases that have the same problem.

Differential Revision: https://reviews.llvm.org/D95088