[all-commits] [llvm/llvm-project] 8bd205: [LangRef] Clarify the behavior of memory access in...

[Juneyoung Lee via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 8bd205bf1de486a32abd956390f6527da4c13e33
      https://github.com/llvm/llvm-project/commit/8bd205bf1de486a32abd956390f6527da4c13e33
  Author: Juneyoung Lee <aqjune at gmail.com>
  Date:   2020-09-26 (Sat, 26 Sep 2020)

  Changed paths:
    M llvm/docs/LangRef.rst

  Log Message:
  -----------
  [LangRef] Clarify the behavior of memory access instructions when pointers/sizes aren't well-defined

This is a patch to LangRef that clarifies the behavior of load/store/memset/memcpy/memmove when the pointers or sizes are not well-defined
as well.

MSan detects a case when e.g., only lower bits of address are garbage when `-msan-check-access-address` is enabled, and it does not directly conflict with this patch because a C program should not use a pointer with undef bits and reasonable optimizations do not convert a well-defined pointer into a pointer with undef bits.

This patch contains a definition of a well-defined value as well.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D87994