[Bug target/60032] [4.9 regression] ICE in reload_cse_simplify_operands, at postreload.c:411

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60032

Alan Modra <amodra at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-02-04
                 CC|                            |amodra at gmail dot com
     Ever confirmed|0                           |1

--- Comment #1 from Alan Modra <amodra at gmail dot com> ---
Reduced testcase

void foo (void)
{
  register float __attribute__ ((mode(SD))) r31 __asm__ ("r31");
  register float __attribute__ ((mode(SD))) fr1 __asm__ ("fr1");

  __asm__ ("#" : "=d" (fr1));
  r31 = fr1;
  __asm__ ("#" : : "r" (r31));
}


This:
enum machine_mode
rs6000_secondary_memory_needed_mode (enum machine_mode mode)
{
  if (mode == SDmode)
    return DDmode;
  return mode;
}

doesn't play well with the following code in reload1.c

#ifdef SECONDARY_MEMORY_NEEDED
  /* If we need a memory location to do the move, do it that way.  */
  else if ((tem1 = replaced_subreg (in), tem2 = replaced_subreg (out),
        (REG_P (tem1) && REG_P (tem2)))
       && REGNO (tem1) < FIRST_PSEUDO_REGISTER
       && REGNO (tem2) < FIRST_PSEUDO_REGISTER
       && SECONDARY_MEMORY_NEEDED (REGNO_REG_CLASS (REGNO (tem1)),
                       REGNO_REG_CLASS (REGNO (tem2)),
                       GET_MODE (out)))
    {
      /* Get the memory to use and rewrite both registers to its mode.  */
      rtx loc = get_secondary_mem (in, GET_MODE (out), opnum, type);

      if (GET_MODE (loc) != GET_MODE (out))
    out = gen_rtx_REG (GET_MODE (loc), reg_or_subregno (out));

      if (GET_MODE (loc) != GET_MODE (in))
    in = gen_rtx_REG (GET_MODE (loc), reg_or_subregno (in));

      gen_reload (loc, in, opnum, type);
      gen_reload (out, loc, opnum, type);
    }
#endif

get_secondary_mem() gives you a DD mem, and the reload out reg
(reg/v:SD 31 31 [ r31 ]) is rewritten to (reg/v:DD 31 31 [ r31 ])

A DDmode requires two gprs when 32-bit, and of course we don't have r32..