[all-commits] [llvm/llvm-project] 39c39e: [MemCpyOpt] Don't shorten memset if destination ob...

[Nikita Popov via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 39c39e8a7f09ff8f0385ef9962d1075d9559d139
      https://github.com/llvm/llvm-project/commit/39c39e8a7f09ff8f0385ef9962d1075d9559d139
  Author: Nikita Popov <nikita.ppv at gmail.com>
  Date:   2020-10-13 (Tue, 13 Oct 2020)

  Changed paths:
    M llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
    M llvm/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll

  Log Message:
  -----------
  [MemCpyOpt] Don't shorten memset if destination observable through unwinding

MemCpyOpt can shorten a memset if it is later partially overwritten
by a memcpy. It checks that the destination is not read in between,
but we also need to make sure that the destination cannot be observed
via unwinding.

Differential Revision: https://reviews.llvm.org/D89190