Quuxplusone added a comment.
This feels like the wrong approach to me... but I admit that I don't know what
the "right" approach might be. (I doubt any right approach exists.)
if (ch == ' ') [[likely]] {
goto whitespace; // A
} else if (ch == '\n' || ch == '\t') [[unlikely]] {
goto whitespace; // B
} else {
foo();
}
[[likely]] whitespace: bar(); // C
It seems like this patch would basically "copy" the `[[likely]]` attribute from
line C up to lines A and B, where it would reinforce the likelihood of path A
and (maybe?) "cancel out" the unlikelihood of path B, without actually saying
anything specifically about the likelihood of label C (which is surely what the
programmer intended by applying the attribute, right?). OTOH, I can't think of
any particular optimization that would care about the likelihood of label C. I
could imagine trying to align label C to a 4-byte boundary or something, but
that wouldn't be an //optimization// on any platform as far as I know.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D86559/new/
https://reviews.llvm.org/D86559
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