[PATCH] D158668: RFC: Add getLikelyBranchWeight helper function

Wed Aug 23 16:38:42 PDT 2023

MatzeB added a comment.

> I'd also posit, that maybe since we're changing this we should reevaluate the numbers we use as defaults.

Heh, same here. Internally we have a handful of functions that end up using `[[likely]]` loop conditions in a triple-nested loops leading to the estimated block frequencies going through the roof and unjustly dominating everything else in the program... Though admittedly I am not decided yet whether I want to blame the 2000:1 ratio or rather the programmers for using the annotation too freely.

There is also a disconnect with the GCC documentation saying `__attribute__((expected))` corresponding to a 99:1 ratio.

Anyway we probably need a separate/patch discussion to not derail this diff too much...

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https://reviews.llvm.org/D158668