https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104334
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |mrs at gcc dot gnu.org,
| |rguenth at gcc dot gnu.org,
| |rsandifo at gcc dot gnu.org
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The difference might be in:
1938 /* Optimize comparisons with constants. */
1939 if (STATIC_CONSTANT_P (yi.len == 1 && yi.val[0] >= 0))
1940 return xi.len == 1 && xi.to_uhwi () < (unsigned HOST_WIDE_INT)
yi.val[0];
1941 if (STATIC_CONSTANT_P (xi.len == 1 && xi.val[0] >= 0))
1942 return yi.len != 1 || yi.to_uhwi () > (unsigned HOST_WIDE_INT)
xi.val[0];
1943 /* Optimize the case of two HWIs. The HWIs are implicitly
sign-extended
1944 for precisions greater than HOST_BITS_WIDE_INT, but sign-extending
both
1945 values does not change the result. */
1946 if (__builtin_expect (xi.len + yi.len == 2, true))
1947 {
1948 unsigned HOST_WIDE_INT xl = xi.to_uhwi ();
1949 unsigned HOST_WIDE_INT yl = yi.to_uhwi ();
1950 return xl < yl;
1951 }
Perhaps with LTO STATIC_CONSTANT_P (yi.len && iy.val[0] >= 0) is true while
without LTO it is false.
I'll verify that. Though, xi.len == 1, xi.to_uhwi () is 3, yi.val[0] is 4 and
yi.to_uhwi () is 0.
So I think if STATIC_CONSTANT_P is true, it will return 3 < 4, while if it is
false, it will return 3 < 0.
Now, the question is, do we consider those wi::lt_p (x, 4, sign) calls invalid
if 4 is not representable in type,
or does the STATIC_CONSTANT_P case need to also check precision, or mask
Xi.val[0]?
And another question is, the 2, 3, 4 cases handling seems like an optimization,
so wi_fold at line 192 should give the right answer, but it doesn't.
