Re: bootstrap failure on ppc64-linux: ICE in set_variable_part

[Janis Johnson <janis187 at us dot ibm dot com>]

On Mon, 2007-09-17 at 23:41 +0200, Andreas Schwab wrote:
> Janis Johnson <janis187@us.ibm.com> writes:
> 
> > Bootstrap of powerpc64-linux fails building libgfortran with:
> >
> > /home/janis/gcc_trunk_anonsvn/gcc/libgfortran/io/read.c: In function 'set_integer':
> > /home/janis/gcc_trunk_anonsvn/gcc/libgfortran/io/read.c:81: internal compiler error: in set_variable_part, at var-tracking.c:2381
> > Please submit a full bug report, with preprocessed source if appropriate.
> > See <http://gcc.gnu.org/bugs.html> for instructions.
> >
> > My last successful build was revision 128522; earliest known break
> > was 128536, still breaks with 128551.
> 
> Bisection has identified this change:
> 
> 2007-09-16  Richard Sandiford  <rsandifo@nildram.co.uk>
> 
> 	* dse.c (find_shift_sequence): Allow word as well as subword shifts.
> 	Do the tentative shift expansion with the DF_NO_INSN_RESCAN flag set.
> 	Fix the call to insn_rtx_cost.  Skip access sizes that require a
> 	real truncation of the store register.  Use convert_move instead
> 	of gen_lowpart when narrowing the result.
> 	(replace_read): Use convert_move instead of gen_lowpart when
> 	narrowing the store rhs.

My hunt just found the same patch  Here's a small test that fails
with cc1 for powerpc64-linux with "-O2 -g -m64 -mstrict-align":
-------------
extern void *memcpy (void *, const void *, signed long);

void
set_integer (void *dest, __int128_t value, int length)
{
  switch (length)
    {
    case 16:
      {
         __int128_t tmp = value;
         memcpy (dest, (void *) &tmp, length);
      }
      break;
    case 1:
      {
        signed char tmp = value;
        memcpy (dest, (void *) &tmp, length);
      }
      break;
    }
}
-----------
Janis