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llvm / llvm-project / 7f4febde1030b8bb409cc56a50e575ff08fcd6ae
commit7f4febde1030b8bb409cc56a50e575ff08fcd6ae[log] [tgz]
authorAmir Ayupov <aaupov@fb.com>Tue May 13 13:20:13 2025 -0700
committerGitHub <noreply@github.com>Tue May 13 13:20:13 2025 -0700
treebbb2df9c35bc906d1916e1b80575e1d959a5846c
parent3b3adefd58826ca4dfd87df8099766d416c54341 [diff]
[BOLT][heatmap] Compute section utilization and partition score (#139193)

Heatmap groups samples into buckets of configurable size (`--block-size`
flag with 64 bytes as the default =X86 cache line size). Buckets are
mapped to containing sections; for buckets that cover multiple sections,
they are attributed to the first overlapping section. Buckets not mapped
to a section are reported as unmapped.

Heatmap reports **section hotness** which is a percentage of samples
attributed to the section.

Define **section utilization** as a percentage of buckets with non-zero
samples relative to the total number of section buckets.

Also define section **partition score** as a product of section hotness
(where total excludes unmapped buckets) and mapped utilization, ranging 
from 0 to 1 (higher is better).

The intended use of new metrics is with **production profile** collected
from BOLT-optimized binary. In this case the partition score of .text
(hot text if function splitting is enabled) reflects **optimization
profile** representativeness and the quality of hot-cold splitting.
Partition score of 1 means that all samples fall into hot text, and all
buckets (cache lines) in hot text are exercised, equivalent to perfect
hot-cold splitting.

Test Plan: updated heatmap-preagg.test
3 files changed
tree: bbb2df9c35bc906d1916e1b80575e1d959a5846c
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. flang-rt/
  11. libc/
  12. libclc/
  13. libcxx/
  14. libcxxabi/
  15. libunwind/
  16. lld/
  17. lldb/
  18. llvm/
  19. llvm-libgcc/
  20. mlir/
  21. offload/
  22. openmp/
  23. polly/
  24. pstl/
  25. runtimes/
  26. third-party/
  27. utils/
  28. .clang-format
  29. .clang-format-ignore
  30. .clang-tidy
  31. .git-blame-ignore-revs
  32. .gitattributes
  33. .gitignore
  34. .mailmap
  35. CODE_OF_CONDUCT.md
  36. CONTRIBUTING.md
  37. LICENSE.TXT
  38. pyproject.toml
  39. README.md
  40. SECURITY.md
README.md

The LLVM Compiler Infrastructure

OpenSSF Scorecard OpenSSF Best Practices libc++

Welcome to the LLVM project!

This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.

C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.

Other components include: the libc++ C++ standard library, the LLD linker, and more.

Getting the Source Code and Building LLVM

Consult the Getting Started with LLVM page for information on building and running LLVM.

For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.

Getting in touch

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The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.