> Dorit Nuzman wrote: > >> H. J. Lu wrote: > >> > >>> Why don't we turn on vectorizer at -O3 or even -O2, depending on > >>> ISA? I added -ftree-vectorize to BOOT_CFLAGS on x86-64. According to > >>> -ftree-vectorizer-verbose=1, there are 82 loops vectorized in > >>> gcc source. There are no regressions. There are not much changes > >>> in bootstrap time as well as "make check" time. > >> We have about two dozen cases of packages that break when > >> -ftree-vectorize is used. I'm sure there are several more as we tend to > >> discourage such bug reports. > >> > > If you could take the time to find the reduced testcases and file PRs for > > these, that would be most appreciated. > > I believe the majority of them can be traced back to PR 25413. For > example building zlib with -O2 -march=pentium4 -ftree-vectorize will > cause several apps that link to it (firefox, openoffice, poppler, etc.) > to segfault. The vectorizer generates movdqa instructions with datarefs > that are not aligned on a 16 byte boundary. >
there is an old patch floating around by Devang to address this problem (as mentioned in the PR). we should push this forward, it's really a simple fix. I'll try to get to it soonish > Other than that, I went through the rest of our -ftree-vectorize bugs > this morning and found that many of them have been fixed in 4.2, so the > situation is much better than I originally thought. > cool! thanks, dorit > > -- > dirtyepic salesman said this vacuum's guaranteed > gentoo org it could suck an ancient virus from the sea > 9B81 6C9F E791 83BB 3AB3 5B2D E625 A073 8379 37E8 (0x837937E8) >