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by blablabla123 462 days ago
True, I also believed it for a second. But it's also easy to blame Ubuntu for errors. IMHO they are doing a quite decent job with assembling their packages. In fact they are also compiled with Stack fortifications. On the other hand I'm glad they are not compiled with the possibly buggy -O3. It can be nice for something performance critical but I definitely don't want a whole system compiled with -O3.
1 comments
kllrnohj 462 days ago
> with the possibly buggy -O3

-O3 isn't buggy on either GCC or Clang. Are you thinking of -Ofast and/or -ffast-math that disregard standards compliance? Those aren't part of -O3.

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BoingBoomTschak 462 days ago
-O3 itself isn't "buggy", but since it uses more optimizations, it can reveal issues in them. Other Gentoo users know: e.g. https://bugs.gentoo.org/show_bug.cgi?id=941208 https://bugs.gentoo.org/show_bug.cgi?id=940923 (search O3 in the bugzilla).
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kllrnohj 462 days ago
strict-aliasing, which is what caused that bug to manifest, is enabled at O2.
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BoingBoomTschak 462 days ago
Yep, it's what caused the bug to manifest, but who knows if that UB would have caused -O2 optimizations to mangle the result as well.

EDIT: first one is -funswitch-loops, though

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kllrnohj 462 days ago
Probably would have. There's no shortage of UB bugs revealed by O2 after all, including major security issues.
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