[Bug c++/99508] New: Asm labels declared inside a function are ignored

[Bug c++/99508] New: Asm labels declared inside a function are ignored

[frank.mehnert at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99508

            Bug ID: 99508
           Summary: Asm labels declared inside a function are ignored
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: frank.mehnert at googlemail dot com
  Target Milestone: ---

This is apparently a gcc-11 regression. Following example:

#include <cstdio>
void foo()
{
  void bar() asm ("bar_assembler");
  extern unsigned buzz asm("buzz_assembler");
  bar();
  printf("%d\n", buzz);
}

Compile this C++ source code with -c and look at the generated symbols with
'objdump -tC'. 

g++-10:
0000000000000000         *UND*  0000000000000000 bar_assembler
0000000000000000         *UND*  0000000000000000 buzz_assembler
0000000000000000         *UND*  0000000000000000 printf

g++-11: (Debian experimental 20210306):
0000000000000000         *UND*  0000000000000000 bar()
0000000000000000         *UND*  0000000000000000 buzz
0000000000000000         *UND*  0000000000000000 printf

g++11 produces the same result as g++10 if 'bar' and 'buzz' are declared
outside foo().

[Bug c++/99508] [11 Regression] Asm labels declared inside a function are ignored

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99508

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
      Known to work|                            |10.2.1
            Summary|Asm labels declared inside  |[11 Regression] Asm labels
                   |a function are ignored      |declared inside a function
                   |                            |are ignored
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Target Milestone|---                         |11.0
           Keywords|                            |wrong-code
   Last reconfirmed|                            |2021-03-10
      Known to fail|                            |11.0

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  Works with the C frontend.

[Bug c++/99508] [11 Regression] Asm labels declared inside a function are ignored

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99508

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |nathan at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
This changed with r11-3699-g4e62aca0e0520e4ed2532f2d8153581190621c1a

[Bug c++/99508] [11 Regression] Asm labels declared inside a function are ignored

[nathan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99508

Nathan Sidwell <nathan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |nathan at gcc dot gnu.org

--- Comment #3 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
Apparently copy_decl doesn't copy_decl :)

[Bug c++/99508] [11 Regression] Asm labels declared inside a function are ignored

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99508

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Nathan Sidwell <nathan@gcc.gnu.org>:

https://gcc.gnu.org/g:b97af562b574697a4fff7fb8c69f579c01e70dec

commit r11-7605-gb97af562b574697a4fff7fb8c69f579c01e70dec
Author: Nathan Sidwell <nathan@acm.org>
Date:   Wed Mar 10 07:39:51 2021 -0800

    c++: Propagate assembler name from local-externs [PR 99508]

    This is another place where our one-true-decl representation breaks
    down.  The fix here propagates the assembly name to the ns-scope
    alias.  that fixes the reported problem but changes the behaviour when
    the user has explicitly declared the entity in its namespace.
    However, we didn't handle that case 'correctly' anyway before.
    Previously we'd also ignore the explicitly specified assembler name,
    now we propagate it.  It's not clear to me what the desired semantics
    would be in decorating just one of the local extern declarations this
    way.  I don't think we can really do better without propagating this
    aliasing property into the middle end (which is also needed for some
    constexpr handling, see PR97306).  I tried that before and it turned
    into a rat-hole.

            PR c++/99508
            gcc/cp/
            * decl.c (make_rtl_for_nonlocal_decl): Propagate local-extern's
            assembler name to the ns alias.
            gcc/testsuite/
            * g++.dg/ext/pr99508.C: New.

[Bug c++/99508] [11 Regression] Asm labels declared inside a function are ignored

[nathan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99508

Nathan Sidwell <nathan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
b97af562b57 2021-03-10 | c++: Propagate assembler name from local-externs [PR
99508]

[Bug c++/99508] [11 Regression] Asm labels declared inside a function are ignored

[frank.mehnert at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99508

--- Comment #6 from Frank Mehnert <frank.mehnert at googlemail dot com> ---
Fix confirmed. Thanks guys!