[Bug target/55461] New: _mm_loadu_si128 generates wrong instruction on 4.8

["andi-gcc at firstfloor dot org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55461

             Bug #: 55461
           Summary: _mm_loadu_si128 generates wrong instruction on 4.8
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: andi-gcc@firstfloor.org


Following test case compiled with -Os -msse4.2 generates with 4.8:

.L3:
        movups  (%rdi), %xmm0         <--------------- wrong data type, should
be movupd
        pcmpistrm       $24, (%rdi,%rsi), %xmm0
        jna     .L2
        addq    $16, %rdi
        jmp     .L3

4.7 gives the correct (although it makes a mess out of the loop):

L3:
        movdqu  (%rdi,%rsi), %xmm1
        movdqu  (%rdi), %xmm2
        pcmpistrm       $24, %xmm1, %xmm2
        jna     .L2
        addq    $16, %rdi
        jmp     .L3


A simpler test case gives the correct movupd, so it must be related to the
funky pointer arithmetic the test case does. But in any case it should not turn
an integer vector into a float vector

#include <nmmintrin.h>

int c_strcmp(char *a, char *b)
{
        unsigned long diff = (unsigned long)b - (unsigned long)a;
        int r = 16;
        a -= r;
        for (;;) {

                if (_mm_cmpistra(_mm_loadu_si128((__m128i *)a),
                                 _mm_loadu_si128((__m128i *)((unsigned long)a +
diff)),
                                 0x18)) {
                        a += r;
                        continue;
                }
                /* check C here */
                return 0;
        }
        return 0;

}