[Bug other/102408] New: [OpenACC] omp-oacc-neuter-broadcast.cc: random() not available on all platforms

[Bug other/102408] New: [OpenACC] omp-oacc-neuter-broadcast.cc: random() not available on all platforms

[pexu@gcc-bugzilla.mail.kapsi.fi]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102408

            Bug ID: 102408
           Summary: [OpenACC] omp-oacc-neuter-broadcast.cc: random() not
                    available on all platforms
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pexu@gcc-bugzilla.mail.kapsi.fi
  Target Milestone: ---
              Host: x86_64-linux-gnu
            Target: x86_64-w64-mingw32

Hi.

random() is not available on all platforms (it's XSI), e.g. mingw.

I wonder if the simplest thing would be simply to use rand() or std::rand()
given that the required random value is quite small?

<...>/gcc/omp-oacc-neuter-broadcast.cc: In function 'void
oacc_do_neutering(long long unsigned int, long long unsigned int)':
<...>/gcc/omp-oacc-neuter-broadcast.cc:1786:23: error: 'random' was not
declared in this scope; did you mean 'rand'?
 1786 |    base = bounds_lo + random () % 512;

The problematic commit:
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=2a3f9f6532bb21d8ab6f16fbe9ee603f6b1405f2

[Bug other/102408] [OpenACC] omp-oacc-neuter-broadcast.cc: random() not available on all platforms

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102408

Thomas Schwinge <tschwinge at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-09-20
                 CC|                            |jules at gcc dot gnu.org,
                   |                            |tschwinge at gcc dot gnu.org
           Keywords|                            |openacc
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |tschwinge at gcc dot gnu.org

--- Comment #1 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
Sorry for the temporary breakage, I'll get this sorted out tomorrow; see
<http://mid.mail-archive.com/87zgsb9t1x.fsf@euler.schwinge.homeip.net>.

[Bug other/102408] [OpenACC] omp-oacc-neuter-broadcast.cc: random() not available on all platforms

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102408

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Thomas Schwinge <tschwinge@gcc.gnu.org>:

https://gcc.gnu.org/g:e87789f197e47259c94349821d3446f7d959e08f

commit r12-3726-ge87789f197e47259c94349821d3446f7d959e08f
Author: Thomas Schwinge <thomas@codesourcery.com>
Date:   Tue Sep 21 08:54:49 2021 +0200

    Evaluate 'random ()' to '0' in 'pass_omp_oacc_neuter_broadcast'

    Julian Brown,
    <http://mid.mail-archive.com/20210920134603.16459021@squid.athome>:

    | [...] the randomness shouldn't be necessary for the
    | correctness of the patch (i.e. it could just be "base = bounds_lo", or
    | indeed folded into the line after).
    |
    | The "ar.invalid ()" case happens when we fail to allocate a block of
    | memory in LDS space for broadcasting a particular set of variables,
    | and trigger a fall-back path in the broadcasting code that adds extra
    | barriers around the broadcast in question. I imagine I was thinking
    | that adding randomness could mean we can "get lucky" sometimes and
    | avoid needing those barriers in some cases, but in fact I don't think
    | that was implemented, so the randomness is useless. (Or it could just
    | have been leftover debug code... oops).

            gcc/
            PR other/102408
            * omp-oacc-neuter-broadcast.cc (oacc_do_neutering): Evaluate
            'random ()' to '0'.

[Bug other/102408] [OpenACC] omp-oacc-neuter-broadcast.cc: random() not available on all platforms

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102408

Thomas Schwinge <tschwinge at gcc dot gnu.org> changed:

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

--- Comment #3 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
Fixed.