From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-139475-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 25583 invoked by alias); 21 Apr 2005 13:07:55 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Received: (qmail 25148 invoked by uid 48); 21 Apr 2005 13:07:45 -0000
Date: Thu, 21 Apr 2005 13:07:00 -0000
From: "julien dot pommier at insa-toulouse dot fr" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20050421130742.21149.julien.pommier@insa-toulouse.fr>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug c/21149] New: invalid code generation for _mm_movehl_ps SSE intrisinc
X-Bugzilla-Reason: CC
X-SW-Source: 2005-04/txt/msg03018.txt.bz2
List-Id: <gcc-bugs.sourceware.org>

The following code does generate wrong results when optimization is turned on :

#include <stdio.h>
#include <xmmintrin.h>

void pv(const char *s, __m128 v) {
  float *p = (float*)&v;
  printf("%s=[%g %g %g %g]\n", s,p[0],p[1],p[2],p[3]);
}

#define P(x) pv(#x,x)


static void plop(__m128 *Y) {
  __m128 zero = _mm_setzero_ps();
  __m128 foo = _mm_movehl_ps(zero, *Y);
  __m128 bar = _mm_movehl_ps(*Y, zero);
  P(*Y);P(foo);P(bar);
}

int main() {
  __m128 y=_mm_set_ps(-3,2,1,9);
  plop(&y); 
  return 0;
}

Here are some outputs:

> gcc-3.4 -O3 -Wall -W -msse  -o toto toto.c && ./toto
*Y=[9 1 2 -3]
foo=[0 0 9 1]
bar=[9 1 0 0]

> gcc-4.0 -g -O0 -Wall -W -msse -o toto toto.c && ./toto
*Y=[9 1 2 -3]
foo=[2 -3 0 0]
bar=[0 0 2 -3]   (this one is correct)

> gcc-4.0 -O3 -Wall -W -msse  -o toto toto.c && ./toto
*Y=[9 1 2 -3]
foo=[9 1 0 0]
bar=[0 0 2 -3]
(same output with gcc-4.1 from cvs)


Tested with:
gcc-3.4 (GCC) 3.4.4 20050314 (prerelease) (Debian 3.4.3-12)
gcc-4.0 (GCC) 4.0.0 20050410 (prerelease) (Debian 4.0-0pre10)
gcc (GCC) 4.0.0 20050418 (prerelease)
gcc (GCC) 4.1.0 20050421 (experimental)

-- 
           Summary: invalid code generation for _mm_movehl_ps SSE intrisinc
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: julien dot pommier at insa-toulouse dot fr
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21149