[Bug target/104815] [nvptx] Use bitbucket operand when REG_UNUSED

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104815

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vr...@gcc.gnu.org>:

https://gcc.gnu.org/g:3ebcc053a4bd32973762b671b444730baf558805

commit r12-7584-g3ebcc053a4bd32973762b671b444730baf558805
Author: Tom de Vries <tdevr...@suse.de>
Date:   Mon Mar 7 14:23:03 2022 +0100

    [nvptx] Use bit-bucket operand for atom insns

    For an atomic fetch operation that doesn't use the result:
    ...
      __atomic_fetch_add (p64, v64, MEMMODEL_RELAXED);
    ...
    we currently emit:
    ...
      atom.add.u64 %r26, [%r25], %r27;
    ...

    Detect the REG_UNUSED reg-note for %r26, and emit instead:
    ...
      atom.add.u64 _, [%r25], %r27;
    ...

    Likewise for all atom insns.

    Tested on nvptx.

    gcc/ChangeLog:

    2022-03-07  Tom de Vries  <tdevr...@suse.de>

            PR target/104815
            * config/nvptx/nvptx.cc (nvptx_print_operand): Handle 'x' operand
            modifier.
            * config/nvptx/nvptx.md: Use %x0 destination operand in atom insns.

    gcc/testsuite/ChangeLog:

    2022-03-07  Tom de Vries  <tdevr...@suse.de>

            PR target/104815
            * gcc.target/nvptx/atomic-bit-bucket-dest.c: New test.