[Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax"

[richardpku at gmail dot com]

#include <stdint.h>
uint64_t extract_double (double x)
{
    union {
        double dbl;
        uint64_t u;
    } t;
    t.dbl = x;
    return t.u;
}

Compile this function with "x86_64-pc-linux-gnu-gcc -O2 -march=core2 -S a.c",
and we get the following assembly codes:

extract_double:
.LFB0:
    .cfi_startproc
    movd    %xmm0, %rax
    ret

The instruction "movd %xmm0, %rax" is nonstandard. Movd should be replaced by
movq.

(GNU assembler silently accepts it as if it were "movq %xmm0, %rax", so it
probably has caused no practical problems.)


-- 
           Summary: x86-64: Nonstandard instruction "movd %xmm0, %rax"
           Product: gcc
           Version: 4.4.3
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: richardpku at gmail dot com
 GCC build triplet: x86_64-linux-gnu
  GCC host triplet: i686-linux-gnu
GCC target triplet: x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215