[Bug tree-optimization/31169] Bootstrap comparison error at revision 122821
------- Comment #37 from rguenth at gcc dot gnu dot org 2007-03-30 10:01 -------
The (target) difference seems to be that I get (on x86_64)
mask_lo_45 = 0x0ffffffffffffffff >> D.33492_44;
with a value range of [0,64] for D.33492_44 and a resulting value range of
[0, +INF] for mask_lo_45, not [+INF, +INF] (which is wrong).
Note that I get the same correct behavior iff changing HWI to 32/64bits and
using -m32. This is the testcase I'm looking at:
#define HOST_WIDE_INT long
#define HOST_BITS_PER_WIDE_INT (8*8)
int
sign_bit_p (int width, HOST_WIDE_INT val_hi, unsigned HOST_WIDE_INT val_lo)
{
unsigned HOST_WIDE_INT mask_lo, lo;
HOST_WIDE_INT mask_hi, hi;
if (width > HOST_BITS_PER_WIDE_INT)
{
hi = (unsigned HOST_WIDE_INT) 1 << (width - HOST_BITS_PER_WIDE_INT - 1);
lo = 0;
mask_hi = ((unsigned HOST_WIDE_INT) -1
>> (2 * HOST_BITS_PER_WIDE_INT - width));
mask_lo = -1;
}
else
{
hi = 0;
lo = (unsigned HOST_WIDE_INT) 1 << (width - 1);
mask_hi = 0;
mask_lo = ((unsigned HOST_WIDE_INT) -1
>> (HOST_BITS_PER_WIDE_INT - width));
}
if ((val_hi & mask_hi) == hi
&& (val_lo & mask_lo) == lo)
return 1;
return 0;
}
can you confirm that this one is miscompiled? I'll try to build a cross
compiler now.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31169
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