[Bug middle-end/70025] New: [6 Regression] Miscompilation of gc-7.4.2 on s390x starting with r227382

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70025

            Bug ID: 70025
           Summary: [6 Regression] Miscompilation of gc-7.4.2 on s390x
                    starting with r227382
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

typedef char (*F) (unsigned long, void *);
typedef union { struct A { char a1, a2, a3, a4; unsigned long a5; F a6; void
*a7; } b; char c[1]; } B;
struct C { const char *c1; unsigned long c2; };
typedef struct D { unsigned long d1; int d2; const char *d3; unsigned long d4,
d5; struct C d6[49]; char d7[8]; } E[1];

__attribute__ ((noinline, noclone))
void foo (register E p)
{
  asm volatile (""::"r" (p):"memory");
}

__attribute__ ((noinline, noclone))
void bar (register E p)
{
  register unsigned long k = p[0].d1 + 1;
  register struct C *l = &((p)[0].d6[(p)[0].d2]);
  register const char *m = l->c1;
  p[0].d1 = k;
  if (*m == '\0')
    {
      register struct A *f = &((B *) m)->b;
      register unsigned long n = l->c2;
      register unsigned long o = n + f->a5;
      if (k < o)
        {
          register unsigned long i;
          register unsigned long q = k + 8;
          register F a6 = f->a6;
          register void *a7 = f->a7;
          if (q > o)
            q = o;
          for (i = k; i < q; i++)
            p[0].d7[i - k] =
              (*a6) (i - n, a7);
          p[0].d4 = k;
          p[0].d3 = p[0].d7;
          p[0].d5 = q;
          return;
        }
    }
  while (p[0].d2 > 0 && l[0].c2 != l[-1].c2)
    {
      p[0].d2--;
      l--;
    }
  if (p[0].d2 == 0)
    {
      p[0].d2 = 0x55555555;
      return;
    }
  p[0].d2--;
  foo (p);
}

char
baz (unsigned long i, void *j)
{
  if (j != 0)
    __builtin_abort ();
  return (char) i;
}

int
main ()
{
  struct D p;
  struct A f;
  __builtin_memset (&f, 0, sizeof (f));
  f.a2 = 4;
  f.a5 = 13;
  f.a6 = baz;
  __builtin_memset (&p, 0, sizeof (p));
  p.d6[0].c1 = (const char *) &f;
  bar (&p);
  if (p.d4 != 1 || p.d5 != 9 || p.d3 != p.d7)
    __builtin_abort ();
  return 0;
}

is miscompiled on s390x-linux, starting with r227382 with -m64 -march=z9-109
-mtune=z10 -O2.
In *.ira we have:
(insn 97 98 191 10 (parallel [
            (set (mem/f:DI (plus:DI (reg/v/f:DI 151 [orig:129 p ] [129])
                        (const_int 16 [0x10])) [4 p_8(D)->d3+0 S8 A64])
                (plus:DI (reg/v/f:DI 151 [orig:129 p ] [129])
                    (const_int 824 [0x338])))
            (clobber (reg:CC 33 %cc))
        ]) cordbscs2.c:36 1267 {*adddi3}
     (expr_list:REG_DEAD (reg/v/f:DI 151 [orig:129 p ] [129])
        (expr_list:REG_UNUSED (reg:CC 33 %cc)
            (nil))))
but LRA incorrectly reloads it as:
(insn 97 98 224 10 (parallel [
            (set (reg/v/f:DI 1 %r1 [orig:129 p ] [129])
                (plus:DI (reg/v/f:DI 1 %r1 [orig:129 p ] [129])
                    (const_int 824 [0x338])))
            (clobber (reg:CC 33 %cc))
        ]) cordbscs2.c:36 1267 {*adddi3}
     (nil))
(insn 224 97 191 10 (set (mem/f:DI (plus:DI (reg/v/f:DI 1 %r1 [orig:129 p ]
[129])
                (const_int 16 [0x10])) [4 p_8(D)->d3+0 S8 A64])
        (reg/v/f:DI 1 %r1 [orig:129 p ] [129])) cordbscs2.c:36 995 {*movdi_64}
     (nil))
Thus it writes correct value to a wrong address.