[Bug inline-asm/20202] New: asm("movq %0, %mm0" : : "X"(*a)) generates invalid asm code

[bero at arklinux dot org]

Compiling the following code results in invalid asm: 
 
#include <stdint.h> 
 
typedef union { 
        int64_t         q; 
} __attribute__ ((aligned (8))) mmx_t; 
 
int main(int argc, char **argv) 
{ 
        mmx_t a; 
        mmx_t *b=&a; 
 
        __asm__ __volatile__("movq %0, %%mm0" : : "X" (*b));    /* produces 
invalid asm code */ 
} 
 
The equivalent 
 
#include <stdint.h> 
 
typedef union { 
        int64_t         q; 
} __attribute__ ((aligned (8))) mmx_t; 
 
int main(int argc, char **argv) 
{ 
        mmx_t a; 
 
        __asm__ __volatile__("movq %0, %%mm0" : : "X" (a));     /* works */ 
} 
 
works. 
 
 
The invalid asm code being generated is "movq %eax,%mm0".

-- 
           Summary: asm("movq %0, %mm0" : : "X"(*a)) generates invalid asm
                    code
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: inline-asm
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bero at arklinux dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-ark-linux
  GCC host triplet: i686-ark-linux
GCC target triplet: i686-ark-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20202