https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77499
--- Comment #7 from avieira at gcc dot gnu.org --- if-convert is a no go here, for the reason Andrew pointed out, sorry missed that comment! So I dont know... Only thing I can think of is better "value-range"-like analysis for combine, but that might be too costly? The fact is that for the code-hoisting to work here, the pseudo for r112 has to be shared among both code-paths, so unless you add an extra move: BB0: r112:SI = r0:SI BB 1: ... r116:SI=r112:SI 0>>0x1 rNEW:SI=zero_extend(r116:SI#0) ... if CC goto BB2 else BB Extra BB 2: r127:SI=rNEW:SI^r129:SI r112:SI=zero_extend(r127:SI#0) if LOOP: goto BB1 else BB exit BB EXTRA: r112:SI=rNEW:SI if LOOP: goto BB1 else BB exit And you end up with an extra move rather than a zero_extend. But maybe the move can be optimized away in later stages? Or maybe put in the same conditional execution block as the XOR...
