https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67609
--- Comment #30 from Vladimir Makarov <vmakarov at gcc dot gnu.org> --- (In reply to Richard Henderson from comment #29) > > > Ho hum. Sorry, Vlad, if I'd bothered bootstrapping I'd have seen this > myself. > Please change != to < in the patch to re-try. (That is, allow the TO mode to > be wider than the FROM mode in order to support the paradoxical subregs seen > above.) Thanks. I've checked the patch on Haswell x86-64 SPEC2000 using -O3 -mtune=corei7. The patch changes code of 3 out of 12 SPECInt tests and 9 of 14 SPECFP tests. The code size always increases. No surprise. But the change is insignificant (about 0.001%). The biggest SPEC rate decrease is achieved on SPECFP and is only about 0.15%. So I guess the patch is ok to fix the problem.