[Bug tree-optimization/127650] New: `va_arg` of an over-aligned emits `movdqa` from an 8-mod-16 address and cause SIGSEGV

[kyuwoncho18 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127650

            Bug ID: 127650
           Summary: `va_arg` of an over-aligned emits `movdqa` from an
                    8-mod-16 address and cause SIGSEGV
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kyuwoncho18 at gmail dot com
  Target Milestone: ---

#include <stdarg.h>
#include <stdio.h>


struct S { long a, b, c, d, e, f, g, h; };
typedef struct S S32 __attribute__((aligned(32)));

struct S gg;

void f (int n, int b, int c, int d, int e, int g, ...)
{
  va_list ap;
  va_start (ap, g);
  long L = va_arg (ap, long);
  gg = va_arg (ap, S32);
  printf ("L=%ld a=%ld h=%ld\n", L, gg.a, gg.h);
  va_end (ap);
}

int
main (void)
{
  S32 s = {0};
  f (0, 1, 2, 3, 4, 5, 0L, s);
  return 0;
}


With -O{1,2,3}, it raises SIGSEGV with movdqa xmm0, xmmword ptr [rsp + 0x104],
and the address was not 16-byte-aligned.

https://gcc.godbolt.org/z/q1bGaKda9