Sam James <s...@gentoo.org> writes: > [[PGP Signed Part:Undecided]] > > Sam James <s...@gentoo.org> writes: > >> Alexe Stefan <stefanalex...@gmail.com> writes: >> >>> Does enabling USE=valgrind impact runtime performance in any way? >> >> A very small amount because it adds a check at runtime for whether >> the application is running under Valgrind. The compiler may be able >> to optimise this a bit if it can determine it's unlikely (if the >> Valgrind headers don't already do this, they should probably mark >> them as cold functions). > > Sorry, I should say, they're hot functions but the if()s for them > should be unlikely()'d.
Alexander Monakov reached out and pointed out this isn't right - they're actually branchless and just encoded in nops, so there's really essentially no runtime cost.
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