[all-commits] [llvm/llvm-project] 3f078b: [AAPointerInfo] OffsetInfo: Unassigned is distinct...

[Sameer Sahasrabuddhe via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 3f078b308bc67d3a05dc0de2588790ed9669febc
      https://github.com/llvm/llvm-project/commit/3f078b308bc67d3a05dc0de2588790ed9669febc
  Author: Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>
  Date:   2022-09-28 (Wed, 28 Sep 2022)

  Changed paths:
    M llvm/include/llvm/Transforms/IPO/Attributor.h
    M llvm/lib/Transforms/IPO/AttributorAttributes.cpp
    A llvm/test/CodeGen/AMDGPU/attributor.ll
    M llvm/test/Transforms/Attributor/value-simplify-pointer-info.ll

  Log Message:
  -----------
  [AAPointerInfo] OffsetInfo: Unassigned is distinct from Unknown

A User like the PHINode may be visited multiple times for the same pointer along
different def-use edges. The uninitialized state of OffsetInfo at the first
visit needs to be distinct from the Unknown value that may be assigned after
processing the PHINode. Without that, a PHINode with all inputs Unknown is never
followed to its uses. This results in incorrect optimization because some
interfering accessess are missed.

Differential Revision: https://reviews.llvm.org/D134704