[PATCH] D61540: [PGO] Use sum of count values to fix func entry count and add a check to verify BFI counts

Wenlei He via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Nov 18 17:48:34 PST 2020


wenlei added a subscriber: hoy.
wenlei added a comment.

> We record function entry count and branch weights and use them to compute the count when needed. This mechanism works well in a perfect world, but often breaks in real programs

We're battling this exact problem from sample PGO side. And we have internal patches for comparing block counts from BFI with ground truth. Perhaps these all can be refactored to be shared between Instr PGO and sample PGO. + at hoy

How does fixing up entry count alone help mitigate this problem?


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