[llvm-branch-commits] [llvm] [BOLT] Match blocks with calls as anchors (PR #96596)

[Davide Italiano via llvm-branch-commits]

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@@ -155,5 +155,51 @@ std::string hashBlockLoose(BinaryContext &BC, const BinaryBasicBlock &BB) {
   return HashString;
 }
 
+/// An even looser hash of a basic block to use with stale profile matching,
+/// composed of the names of a block's called functions in lexicographic order.
+std::string hashBlockCalls(BinaryContext &BC, const BinaryBasicBlock &BB) {
+  // The hash is computed by creating a string of all lexicographically ordered
+  // called function names.
+  std::multiset<std::string> FunctionNames;
+  for (const MCInst &Instr : BB) {
+    // Skip non-call instructions.
+    if (!BC.MIB->isCall(Instr))
+      continue;
+    const MCSymbol *CallSymbol = BC.MIB->getTargetSymbol(Instr);
+    if (!CallSymbol)
+      continue;
+    FunctionNames.insert(std::string(CallSymbol->getName()));
+  }
+
+  std::string HashString;
+  for (const std::string &FunctionName : FunctionNames)
+    HashString.append(FunctionName);
+
+  return HashString;
+}
+
+/// The same as the above function, but for profiled functions.
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dcci wrote:

functions can be moved around the file, I wouldn't  say "same as above" -- as above can change.

https://github.com/llvm/llvm-project/pull/96596