[llvm-branch-commits] [BOLT] Hash-based function matching (PR #95821)

[via llvm-branch-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-bolt

Author: shaw young (shawbyoung)

<details>
<summary>Changes</summary>

Using the hashes of binary and profiled functions
to recover functions with changed names.

Test Plan: tbd


---
Full diff: https://github.com/llvm/llvm-project/pull/95821.diff


1 Files Affected:

- (modified) bolt/lib/Profile/YAMLProfileReader.cpp (+17) 


``````````diff
diff --git a/bolt/lib/Profile/YAMLProfileReader.cpp b/bolt/lib/Profile/YAMLProfileReader.cpp
index f25f59201f1cd..f0fcb1c130002 100644
--- a/bolt/lib/Profile/YAMLProfileReader.cpp
+++ b/bolt/lib/Profile/YAMLProfileReader.cpp
@@ -415,6 +415,23 @@ Error YAMLProfileReader::readProfile(BinaryContext &BC) {
     if (!YamlBF.Used && BF && !ProfiledFunctions.count(BF))
       matchProfileToFunction(YamlBF, *BF);
 
+  // Uses the strict hash of profiled and binary functions to match functions
+  // that are not matched by name or common name.
+  std::unordered_map<size_t, BinaryFunction*> StrictBinaryFunctionHashes;
+  StrictBinaryFunctionHashes.reserve(BC.getBinaryFunctions().size());
+
+  for (auto& [_, BF] : BC.getBinaryFunctions()) {
+    StrictBinaryFunctionHashes[BF.getHash()] = &BF;
+  }
+
+  for (auto YamlBF : YamlBP.Functions) {
+    auto It = StrictBinaryFunctionHashes.find(YamlBF.Hash);
+    if (It != StrictBinaryFunctionHashes.end() && !ProfiledFunctions.count(It->second)) {
+      auto *BF = It->second;
+      matchProfileToFunction(YamlBF, *BF);
+    }
+  }
+
   for (yaml::bolt::BinaryFunctionProfile &YamlBF : YamlBP.Functions)
     if (!YamlBF.Used && opts::Verbosity >= 1)
       errs() << "BOLT-WARNING: profile ignored for function " << YamlBF.Name

``````````

</details>


https://github.com/llvm/llvm-project/pull/95821