[all-commits] [llvm/llvm-project] 9d1880: [libcxx] Remove empty ~__no_destroy

Vitaly Buka via All-commits all-commits at lists.llvm.org
Fri Apr 26 15:25:50 PDT 2024


  Branch: refs/heads/users/vitalybuka/spr/libcxx-avoid-__cxa_atexit-with-o0
  Home:   https://github.com/llvm/llvm-project
  Commit: 9d18805ac5395158a2a80fd2efd5edac46c70d28
      https://github.com/llvm/llvm-project/commit/9d18805ac5395158a2a80fd2efd5edac46c70d28
  Author: Vitaly Buka <vitalybuka at google.com>
  Date:   2024-04-26 (Fri, 26 Apr 2024)

  Changed paths:
    M libcxx/include/__utility/no_destroy.h
    A libcxx/test/libcxx/utilities/no_destroy.pass.cpp

  Log Message:
  -----------
  [libcxx] Remove empty ~__no_destroy

Primary motivation is that after #84651 msan will
complain if fields accessed after ~__no_destroy.

Previously msan assumed that __obj_ will have own
destructor, were we will poison the field, but it never
happened before.

After #84651 msan will complain on any field access
after `~__no_destroy`.

As is Msan does validate fields destruction order for
classes with trivial destructor.

Additionally empty destructor will register __cxa_atexit with -O0.
https://gcc.godbolt.org/z/hce587b65

We can not remove the destructor with union where
_Tp can have non-trivial destructor.

But we can remove destructor if we use in-place
new instead of union.
https://gcc.godbolt.org/z/Yqxx57eEd - empty even with -O0.

Reviewers: #reviewers-libcxx

Pull Request: https://github.com/llvm/llvm-project/pull/89882


  Commit: ac1587b0be1bbbeffb2b533c77af74415a89b802
      https://github.com/llvm/llvm-project/commit/ac1587b0be1bbbeffb2b533c77af74415a89b802
  Author: Vitaly Buka <vitalybuka at google.com>
  Date:   2024-04-26 (Fri, 26 Apr 2024)

  Changed paths:
    M libcxx/include/__utility/no_destroy.h

  Log Message:
  -----------
  Remove "unsigned"


  Commit: 15239a6aea6d71440d30e59ac7123d8241f5a993
      https://github.com/llvm/llvm-project/commit/15239a6aea6d71440d30e59ac7123d8241f5a993
  Author: Vitaly Buka <vitalybuka at google.com>
  Date:   2024-04-26 (Fri, 26 Apr 2024)

  Changed paths:
    M libcxx/include/__utility/no_destroy.h
    M libcxx/test/libcxx/utilities/no_destroy.pass.cpp

  Log Message:
  -----------
  Move field initialized and add constinit test


  Commit: acd61a447b73e1a20c63628ac7d0c66e3b734e06
      https://github.com/llvm/llvm-project/commit/acd61a447b73e1a20c63628ac7d0c66e3b734e06
  Author: Vitaly Buka <vitalybuka at google.com>
  Date:   2024-04-26 (Fri, 26 Apr 2024)

  Changed paths:
    M libcxx/test/libcxx/utilities/no_destroy.pass.cpp

  Log Message:
  -----------
  Inline test


  Commit: 5487aaffa8c975747aaf705664be30351b12736c
      https://github.com/llvm/llvm-project/commit/5487aaffa8c975747aaf705664be30351b12736c
  Author: Vitaly Buka <vitalybuka at google.com>
  Date:   2024-04-26 (Fri, 26 Apr 2024)

  Changed paths:
    M libcxx/test/libcxx/utilities/no_destroy.pass.cpp

  Log Message:
  -----------
  reorder test


Compare: https://github.com/llvm/llvm-project/compare/bd0af57f1ae6...5487aaffa8c9

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