http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306
Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org --- Comment #23 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-01-10 11:26:09 UTC --- It generally depends on the branch cost, e.g. out of #c19 testcase on x86_64 we generate: D.1729 = b1 != 0; D.1730 = b2 != 0; D.1731 = D.1729 & D.1730; if (D.1731 != 0) goto <D.1732>; else goto <D.1727>; <D.1732>: D.1733 = b3 != 0; D.1734 = b4 != 0; D.1735 = D.1733 & D.1734; if (D.1735 != 0) goto <D.1736>; else goto <D.1727>; <D.1736>: etc., but on other targets it could have just one comparison per conditional jump, or on the other side 4. While the tests don't have side-effects, turning too many &&s into &s wouldn't result in very good code, though of course would make it easier to perform some optimizations. Anyway, you can write it in the source as a series of ifs: array[0] = 1; if (!b1) array[0] = 0; else if (!b2) array[0] = 0; else if (!b3) array[0] = 0; ... and we wouldn't be able to optimize it anyway.