[Bug tree-optimization/41857] New: Loop optimizer breaks __ea pointers with -mea64

["uweigand at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

The following test case

__ea char *strchr_ea (__ea const char *s, int c);
__ea char *foo (__ea char *s)
{
  __ea char *ret = s;
  int i;

  for (i = 0; i < 3; i++)
    ret = strchr_ea (ret, s[i]);

  return ret;
}

results in an ICE when compiled with -O -mea64.

The reason is that the loop optimizers use an induction variable
of type "long long int" to represent s+i, instead of using the
appropriate pointer type.

This causes rewrite_use_address to call create_mem_ref with an
affine expression none of whose subexpressions is of pointer type.
Therefore, the induction variable is assigned as the "index" of
a TARGET_MEM_REF, which means it gets converted to sizetype.

As sizetype is smaller than the __ea pointer type in the -ea64 case,
this means that value would be truncated.  This is later caught by
an assertion in convert_memory_address, which causes the ICE.

Note that use of an integral induction variable was introduced as
part of the fix to PR tree-optimization/27865:
http://gcc.gnu.org/ml/gcc-patches/2006-08/msg00198.html

It seems to me it would be preferable to keep using pointer variables
where possible, even on platforms where sizetype is the same size as
pointers, in order to properly identify address base registers where
this makes a performance difference.


-- 
           Summary: Loop optimizer breaks __ea pointers with -mea64
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: uweigand at gcc dot gnu dot org
        ReportedBy: uweigand at gcc dot gnu dot org
GCC target triplet: spu-unknown-elf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41857