[Bug c++/68484] New: _mm_storel_epi64((__m128i *)x, m); does nothing if "x" is a "volatile" ptr

[vvsed at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68484

            Bug ID: 68484
           Summary: _mm_storel_epi64((__m128i *)x, m); does nothing if "x"
                    is a "volatile" ptr
           Product: gcc
           Version: 5.1.0
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vvsed at hotmail dot com
  Target Milestone: ---

Created attachment 36803
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36803&action=edit
It's *.ii file for the above source.

The following program prints "0 0" instead of "1 1".
If we use _mm_storel_pi() instead of _mm_storel_epi64(), it's OK.
The CPU is Intel Haswell with Windows 7.1.
Same with 4.8, 4.9, 5.1 g++ versions.


/*
D:\Tools\MinGW64\bin\g++.exe -m64 -O2 -Wall -Wextra -save-temps gcerr.cpp
-ovx_class_gc

Compiler: http://tdm-gcc.tdragon.net/about

_mm_storel_epi64((__m128i *)x, m); does nothing if "x" is a "volatile" ptr
*/

#include <stdio.h>
#include <emmintrin.h>

int main(int argc, const char *argv[])
{
        int     _x[2] = {0};
        int * volatile x = _x;
        __m128i m = _mm_set1_epi32(1);
        char    s[1];

        _mm_storel_epi64((__m128i *)x, m);
//      _mm_storel_pi((__m64 *)x, *(__m128 *)&m);       //OK

        fprintf(stdout, "%d %d \npress Enter", x[0], x[1]);

        gets(s);
        return 0;
}