[all-commits] [llvm/llvm-project] 213124: [LLVM][MemCpyOpt] Unify alias tags if we optimize ...

[Dominik Adamski via All-commits]

  Branch: refs/heads/release/20.x
  Home:   https://github.com/llvm/llvm-project
  Commit: 2131242240f71926e45e58ad6ec66aced4756e48
      https://github.com/llvm/llvm-project/commit/2131242240f71926e45e58ad6ec66aced4756e48
  Author: Dominik Adamski <dominik.adamski at amd.com>
  Date:   2025-04-15 (Tue, 15 Apr 2025)

  Changed paths:
    M llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
    A llvm/test/Transforms/MemCpyOpt/memcpy-tbaa.ll
    M llvm/test/Transforms/MemCpyOpt/stack-move.ll

  Log Message:
  -----------
  [LLVM][MemCpyOpt] Unify alias tags if we optimize allocas (#129537)

Optimization of alloca instructions may lead to invalid alias tags.
Incorrect alias tags can result in incorrect optimization outcomes for
Fortran source code compiled by Flang with flags: `-O3 -mmlir
-local-alloc-tbaa -flto`.

This commit removes alias tags when memcpy optimization replaces two
arrays with one array, thus ensuring correct compilation of Fortran
source code using flags: `-O3 -mmlir -local-alloc-tbaa -flto`.

This commit is also a proposal to fix the reported issue:
https://github.com/llvm/llvm-project/issues/133984

---------

Co-authored-by: Shilei Tian <i at tianshilei.me>
(cherry picked from commit 716b02d8c575afde7af1af13df145019659abca2)



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