[llvm] [StructuralHash] Global Variable (PR #118412)

[Kyungwoo Lee via llvm-commits]

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@@ -65,19 +65,44 @@ class StructuralHashImpl {
     }
   }
 
-  stable_hash hashAPInt(const APInt &I) {
+  static stable_hash hashAPInt(const APInt &I) {
     SmallVector<stable_hash> Hashes;
     Hashes.emplace_back(I.getBitWidth());
     auto RawVals = ArrayRef<uint64_t>(I.getRawData(), I.getNumWords());
     Hashes.append(RawVals.begin(), RawVals.end());
     return stable_hash_combine(Hashes);
   }
 
-  stable_hash hashAPFloat(const APFloat &F) {
+  static stable_hash hashAPFloat(const APFloat &F) {
     return hashAPInt(F.bitcastToAPInt());
   }
 
-  stable_hash hashGlobalValue(const GlobalValue *GV) {
+  static stable_hash hashGlobalVariable(const GlobalVariable &GVar) {
+    if (!GVar.hasInitializer())
+      return hashGlobalValue(&GVar);
+
+    // Hash the contents of a string.
+    if (GVar.getName().starts_with(".str"))
+      return hashConstant(GVar.getInitializer());
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kyulee-com wrote:

I only use `hashInitializer()` to determine if the global variable (beginning with `.str`) has an initializer. While I don't specifically verify if it's a string literal, this approach should suffice for most scenarios. It's still safe for our purposes, even if it's not a string literal. The only concern is avoiding an initializer that recursively references the current global variable itself. I assume that the cases filtered out here and below do not include such instances.

https://github.com/llvm/llvm-project/pull/118412