https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109907
--- Comment #16 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #14)
> Actually I take back on what is going on those 3. But I will be looking into
> it.
>
>
> x.0_1 = (signed long) x_4(D);
> _2 = x.0_1 >> 31;
> _3 = (unsigned char) _2;
> _5 = _3 & 1;
we could pattern match this on the gimple using something like:
(simplify
(bit_and (convert? (rshift (nop_convert? @1) INTEGER_CST@2)) integer_onep)
(if (wi::to_wide (@2) == TYPE_PRECISION (TREE_TYPE (@0)) - 1)
(with
{ tree utype = unsigned_type_for (type); }
(convert (rshift (convert:utype @1) @2)))
But that still fails because combine really does not like subregs:
Trying 6 -> 12:
6: r47:SI=r48:SI 0>>0x1f
REG_DEAD r48:SI
12: r24:QI=r47:SI#0
REG_DEAD r47:SI
Failed to match this instruction:
(set (reg/i:QI 24 r24)
(subreg:QI (lshiftrt:SI (reg:SI 48)
(const_int 31 [0x1f])) 0))
