[PATCH] D156278: [BOLT] Fine-tuning hash computation for stale matching

[Sergey Pupyrev via Phabricator via llvm-commits]

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spupyrev retitled this revision from "[BOLT] better hashing" to "[BOLT] Fine-tuning hash computation for stale matching".
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minor tweaks


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fixing tests


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adding a test check


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added a test


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Ready for review now


Fine-tuning hash computation for stale matching:

- introducing a new "loose" basic block hash that allows to match many more blocks than before;
- tweaking params of the inference algorithm that find (slightly) better solutions;
- added more meaningful tests for stale matching.

Tested the changes on several open-source benchmarks (clang, rocksdb, chrome) 
and one prod workload using different compiler modes (LTO/PGO etc). There is
always an improvement in the quality of inferred profiles.
(The current implementation is still not optimal but the diff is a step forward;
I am open to further suggestions)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D156278

Files:
  bolt/include/bolt/Core/HashUtilities.h
  bolt/include/bolt/Core/MCPlusBuilder.h
  bolt/lib/Core/HashUtilities.cpp
  bolt/lib/Profile/StaleProfileMatching.cpp
  bolt/lib/Target/X86/X86MCPlusBuilder.cpp
  bolt/test/X86/Inputs/blarge_profile_stale.yaml
  bolt/test/X86/reader-stale-yaml.test

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