[Bug inline-asm/32971] New: Inline asm with offset addressing fails to compile in 4.0+ without -O

["kinetik at orcon dot net dot nz" <gcc-bugzilla at gcc dot gnu dot org>]

The following test case fails to compile without optimization with gcc 4.3.0
(20070503 (experimental)), 4.1.2 (20070502 (Red Hat 4.1.2-12)), and 4.0.4
(20060904 (prerelease) (Debian 4.0.3-7)), but succeeds with 3.3.6 (Debian
1:3.3.6-15) and 3.4.6 (Debian 3.4.6-5).  With optimization (-O and -O2), it
compiles fine with all of the gcc versions mentioned above.

The failing configurations are generating invalid assembly and gas emits the
following error:
/tmp/ccnbmIy1.s:12: Error: register value used as expression

Looking at the assembly emitted by gcc, the failing case looks like:
        lea (%edx)(%eax), %eax

..and with the working configurations, I get the expected code:
        lea 4(%eax), %eax

#include <stddef.h>

struct coord { int x; int y; };

int *
foo(struct coord * c)
{
  int * i;
  asm ("lea %1(%2), %0"
       : "=r" (i)
       : "m" (*(size_t *) offsetof(struct coord, y)),
         "r" (c)
       : "memory");
  return i;
}


-- 
           Summary: Inline asm with offset addressing fails to compile in
                    4.0+ without -O
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: inline-asm
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kinetik at orcon dot net dot nz
 GCC build triplet: i486-linux-gnu
  GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32971