Fixes#202374.
Preserve LLVM function `!prof` metadata for:
- `synthetic_function_entry_count`
- `function_entry_count` with import GUID operands
The importer represents the entry count, count kind, and trailing import
GUID operands in a single `#llvm.function_entry_count` attribute,
validates malformed operands before mutating the operation, and exports
the metadata through `llvm::Function::setEntryCount`.
Tests cover import, export, malformed metadata operands, synthetic
counts, synthetic counts with trailing operands, import GUID
round-tripping, and raw i64 bit-pattern preservation.
Checks:
- `git diff --check`
- `git clang-format --diff origin/main -- ...`
- `llvm-as -disable-output` smoke check
Codex was used in making this PR.
1sgtpepper
8518c74b5e