[Bug middle-end/47895] New: usage of __attribute__ ((__target__ ("xyz"))) with buitins

[Bug middle-end/47895] New: usage of __attribute__ ((__target__ ("xyz"))) with buitins

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47895

           Summary: usage of __attribute__ ((__target__ ("xyz"))) with
                    buitins
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: vincenzo.innocente@cern.ch


I would like to generate code for multiple targets from the same source when
using builtins
(
I think that this issue has been discussed before for instance in
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39840
) 


I have code as in the example below that compiles only with -mavx.
In such a case it will use AVX instruction for all functions including the one
"targetted" for sse3
while I would like to obtain an object file that I can run on multiple
platform.
This problem occurs only when builtins are used: standard c code is correctly
emitted accordingly to the target provided that the minimal -m is used.

Is there any preprocessor flag to "activate" all intrinsics and builtins in
x86intrin.h?

-----------------------------
example

#include <x86intrin.h>

float  __attribute__ ((__target__ ("sse3"))) sum3(float const * __restrict__ x,
float const * __restrict__ y, float const * __restrict__ z) {
  __m128 sum = _mm_setzero_ps();
  for (int i=0; i!=1024; i+=4)
    sum  += _mm_add_ps(_mm_loadu_ps(z+i),
                       _mm_mul_ps(_mm_loadu_ps(x+i),_mm_loadu_ps(y+i)) );
    sum = _mm_hadd_ps(sum,sum);
    sum = _mm_hadd_ps(sum,sum);
  float ret;
  _mm_store_ss(&ret,sum);
  return ret;
}

float  __attribute__ ((__target__ ("avx"))) sumv(float const * __restrict__ x,
float const * __restrict__ y, float const * __restrict__ z) {
  __m256 sum = _mm256_setzero_ps();
  for (int i=0; i!=1024; i+=8)
    sum  += _mm256_add_ps(_mm256_loadu_ps(z+i),
                       _mm256_mul_ps(_mm256_loadu_ps(x+i),_mm256_loadu_ps(y+i))
);
    sum = _mm256_hadd_ps(sum,sum);
    sum = _mm256_hadd_ps(sum,sum);
    sum = _mm256_hadd_ps(sum,sum);
  float ret[8];
  _mm256_store_ps(ret,sum);
  return ret[0];
}

[Bug middle-end/47895] usage of __attribute__ ((__target__ ("xyz"))) with buitins

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47895

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-02-25 14:44:27 UTC ---
A way easier and more portable way is to split your source into multiple
compilation units and use appropriate flags to compile them.

[Bug middle-end/47895] usage of __attribute__ ((__target__ ("xyz"))) with buitins

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47895

--- Comment #2 from vincenzo Innocente <vincenzo.innocente at cern dot ch> 2011-02-26 09:55:03 UTC ---
I find that the solution with multiple files shifts the problem to the build
system, which is not necessarily an easier solution in all projects, and make
maintenance more difficult as more files need to be tracked for each single
algorithm.
I would much prefer a solution that is fully confined to the source code
without involving the configuration and build system. 

In any case at the moment there is a clear unbalance between plane c code, for
which a single compilation unit with multiple functions for different "targets"
do work, and code exploiting builtins for which __attribute__ ((__target__
("xyz"))) is not ineffective.
I consider this behavior a defect.

[Bug middle-end/47895] usage of __attribute__ ((__target__ ("xyz"))) with buitins

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47895

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
             Target|                            |x86_64
         Resolution|---                         |FIXED
   Target Milestone|---                         |4.9.0
      Known to work|                            |4.9.0, 5.1.0

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This has been fixed since GCC 4.9.0.

[Bug middle-end/47895] usage of __attribute__ ((__target__ ("xyz"))) with buitins

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47895

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This was fixed by r0-124016.