[Bug rtl-optimization/55686] [4.8 Regression] ICE in assign_by_spills, at lra-assigns.c:1244

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55686

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-12-14 
11:26:15 UTC ---
Even more reduced:

struct S { unsigned long *s, *t; };
unsigned long *q;

void
foo (struct S *x, unsigned long y, unsigned long z, int w)
{
  unsigned long *d = x->t, j;
  if (w)
    for (j = 0; j < z; j++)
      *d++ = q[-j];
  register unsigned long *g __asm__ ("edi");
  register struct S *h __asm__ ("esi");
  h->s = g;
  h->t--;
  foo (h, h->t[-1], g[1], (int) g[2]);
  goto *(void *) *g;
}

ICEd with reload too, starting with
http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=185465
The reload ICE was
pr55686.c: In function ‘foo’:
pr55686.c:17:1: error: unable to find a register to spill in class ‘DIREG’
pr55686.c:17:1: error: this is the insn:
(insn 29 28 30 5 (parallel [
            (set (mem:SI (reg/v/f:SI 1 dx [orig:66 d ] [66]) [4 MEM[base: d_9,
offset: 4294967292B]+0 S4 A32])
                (reg:SI 0 ax [orig:67 D.1379 ] [67]))
            (set (reg/v/f:SI 1 dx [orig:66 d ] [66])
                (plus:SI (reg/v/f:SI 1 dx [orig:66 d ] [66])
                    (const_int 4 [0x4])))
        ]) pr55686.c:10 883 {*strsetsi_1}
     (expr_list:REG_DEAD (reg:SI 0 ax [orig:67 D.1379 ] [67])
        (nil)))
pr55686.c:17:1: internal compiler error: in spill_failure, at reload1.c:2120
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.