[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
