Amir Ayupov c00c62c113 [BOLT] Add pseudo probe inline tree to YAML profile ...

Add probe inline tree information to YAML profile, at function level:
- function GUID,
- checksum,
- parent node id,
- call site in the parent.

This information is used for pseudo probe block matching (#99891).

The encoding adds/changes probe information in multiple levels of
YAML profile:
- BinaryProfile: add pseudo_probe_desc with GUIDs and Hashes, which
  permits deduplication of data:
  - many GUIDs are duplicate as the same callee is commonly inlined
    into multiple callers,
  - hashes are also very repetitive, especially for functions with
    low block counts.
- FunctionProfile: add inline tree (see above). Top-level function
  is included as root of function inline tree, which makes guid and
  pseudo_probe_desc_hash fields redundant.
- BlockProfile: densely-encoded block probe information:
  - probes reference their containing inline tree node,
  - separate lists for block, call, indirect call probes,
  - block probe encoding is specialized: ids are encoded as bitset
    in uint64_t. If only block probe with id=1 is present, it's
    encoded as implicit entry (id=0, omitted).
  - inline tree nodes with identical probes share probe description
    where node indices are combined into a list.

On top of #107970, profile with new probe encoding has the following
characteristics (profile for a large binary):

- Profile without probe information: 33MB, 3.8MB compressed (baseline).
- Profile with inline tree information: 92MB, 14MB compressed.

Profile processing time (YAML parsing, inference, attaching steps):
- profile without pseudo probes: 5s,
- profile with pseudo probes, without pseudo probe matching: 11s,
- with pseudo probe matching: 12.5s.

Test Plan: updated pseudoprobe-decoding-inline.test

Reviewers: wlei-llvm, ayermolo, rafaelauler, dcci, maksfb

Reviewed By: wlei-llvm, rafaelauler

Pull Request: https://github.com/llvm/llvm-project/pull/107137

2024-09-12 20:51:35 -07:00

5.1 KiB

Raw Blame History

View Raw