[all-commits] [llvm/llvm-project] 4d859d: [MemCpyOpt] fix incorrect handling of lifetime mar...

[Jameson Nash via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4d859dbae1a29a5fcc14f2e7e324324796ed263b
      https://github.com/llvm/llvm-project/commit/4d859dbae1a29a5fcc14f2e7e324324796ed263b
  Author: Jameson Nash <vtjnash at gmail.com>
  Date:   2025-07-26 (Sat, 26 Jul 2025)

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

  Log Message:
  -----------
  [MemCpyOpt] fix incorrect handling of lifetime markers (#143782)

Having lifetime markers should only increase the information available
to LLVM, but it would instead rely on the callback to entirely give up
if it encountered a lifetime marker that wasn't full size, but
sub-optimal lifetime markers are not supposed to be forbidding
optimizations that would otherwise apply if they were either absent or
optimal. This pass wasn't tracking GEP offsets either, so it wasn't
quite correctly handled either, although earlier sub-optimal checks
that this size is the same as the alloca test made this safe in the
past, and unlikely to have encountered anything else in the past.



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