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Re: Any way to do branch hints?
> Andrew Pinski <firstname.lastname@example.org> writes:
> > Yes,
> > __builtin_expect.
> Intel P4 has a new branch hint prefix for conditional jumps, but afaik
> gcc doesn't generate it right now even with -march=pentium4 and
> __builtin_expect. I think that is what Kean asked about.
GCC should generate these on __builtin_expect and friends even on
-mcpu=pentium4, but we usually manage to redirect things in a way so the
prefixes are not needed.
> Of course you get some part of this from the block reordering
> and the "if it jumps backwards it must be taken" heuristics,
> but telling the CPU explicitely may be a stronger hint.