http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54116
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-07-29
10:13:41 UTC ---
The tree level looks correct:
<bb 4>:
# ivtmp.23_69 = PHI <ivtmp.23_68(5), ivtmp.23_66(3)>
D.1771_65 = (void *) ivtmp.23_69;
D.1717_6 = MEM[base: D.1771_65, offset: 0B];
D.1722_10 = MEM[base: D.1771_65, offset: 4B];
D.1723_11 = D.1722_10 | D.1717_6;
D.1727_15 = MEM[base: D.1771_65, offset: 8B];
D.1731_19 = MEM[base: D.1771_65, offset: 12B];
D.1732_20 = D.1731_19 | D.1727_15;
D.1733_21 = D.1732_20 | D.1723_11;
ivtmp.23_68 = ivtmp.23_69 + 16;
if (D.1733_21 != 0)
goto <bb 6>;
else
goto <bb 5>;
<bb 5>:
goto <bb 4>;
<bb 6>:
# D.1723_22 = PHI <D.1723_11(4), D.1723_36(2)>
# D.1732_23 = PHI <D.1732_20(4), D.1732_45(2)>
D.1737_25 = D.1723_22 * D.1732_23;
return D.1737_25;
--- CUT ----
Are you trying to say GCC should copy the loop header in this case?
Or keeping around x[i]|x[i+1] and x[i+2]|x[i+3] result increases register
pressure and exposes issues with 2-operand machines in some cases?
