[Bug target/24306] [3.4/4.0/4.1/4.2 Regression] va_arg gets confused when skipping over certain zero-sized types with -msse

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

------- Comment #5 from rguenth at gcc dot gnu dot org  2005-12-19 11:34 -------
We add some alignment fluff in the SSE type case.  The following works as
expected:

#include <stdarg.h>

typedef int __attribute__ ((vector_size (16))) foo_t;
extern void abort(void);

struct s
{
  _Complex double f[0];
} s1;

void
check (int x, ...)
{
  int y;
  va_list ap;

  va_start (ap, x);
  va_arg (ap, struct s);
  y = va_arg (ap, int);

  /* Expect output: 3 7  */
  if (y != 7)
    abort ();
}

int main()
{
  check (3, s1, 7);
  return 0;
}

.vars dump difference, working agains non-working:

--- t2.c.t96.vars       2005-12-19 12:22:09.000000000 +0100
+++ t.c.t96.vars        2005-12-19 12:15:08.000000000 +0100
@@ -5,10 +5,12 @@
 {
   char * ap;
   char * D.1699;
+  char * ap.0;

 <bb 2>:
   __builtin_va_start (&ap, 0, 0);
-  D.1699 = ap;
+  ap.0 = ap;
+  D.1699 = ap.0 + 15B & -16B;
   if (*(int *) D.1699 != 7) goto <L0>; else goto <L1>;

 <L0>:;


We have a bug here in the generic builtins.c and the config/i386/i386.c variant
of gimplify_va_arg_expr - and I have a fix.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2005-10-11 14:02:39         |2005-12-19 11:34:31
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24306