https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109907
--- Comment #23 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
Thank you so much for looking into this.
For the test case from comment #21 though, the problem is somewhere in tree
optimizations.
> unsigned char lfsr32_mpp_ge0 (unsigned long number)
> {
> unsigned char b = 0;
> if (number >= 0) b--;
> if (number & (1UL << 29)) b++;
> if (number & (1UL << 13)) b++;
>
> return b;
> }
The -fdump-tree-optimized dump reads:
;; Function lfsr32_mpp_ge0 (lfsr32_mpp_ge0, funcdef_no=0, decl_uid=1880,
cgraph_uid=1, symbol_order=0)
unsigned char lfsr32_mpp_ge0 (long unsigned int number)
{
unsigned char b;
long unsigned int _1;
long unsigned int _2;
_Bool _3;
unsigned char _8;
_Bool _9;
unsigned char _10;
unsigned char _11;
<bb 2> [local count: 1073741824]:
_1 = number_5(D) & 536870912;
_2 = number_5(D) & 8192;
if (_2 != 0)
goto <bb 4>; [50.00%]
else
goto <bb 3>; [50.00%]
<bb 3> [local count: 536870912]:
_9 = _1 == 0;
_10 = (unsigned char) _9;
_11 = -_10;
goto <bb 5>; [100.00%]
<bb 4> [local count: 536870913]:
_3 = _1 != 0;
_8 = (unsigned char) _3;
<bb 5> [local count: 1073741824]:
# b_4 = PHI <_11(3), _8(4)>
return b_4;
}
The ANDs are expanded by expand_binop() and later passes have to deal with the
32-bit arithmnetic. combine finds one combination of andsi3 into
"*sbrx_and_branch<mode>_split" with mode=si, but apart from that the mess still
lives in asm.
