[clang] [compiler-rt] [llvm] [ASan] Add metadata to renamed instructions so ASan doesn't use the i… (PR #119387)

[Florian Hahn via llvm-commits]

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@@ -3391,6 +3391,27 @@ static void findStoresToUninstrumentedArgAllocas(
   }
 }
 
+StringRef getAllocaName(AllocaInst *AI) {
+  // Alloca could have been renamed for uniqueness. Its true name will have been
+  // recorded as an annotation.
+  if (AI->hasMetadata(LLVMContext::MD_annotation)) {
+    MDTuple *Annotation =
+        (MDTuple *)AI->getMetadata(LLVMContext::MD_annotation);
+    for (int i = 0; i < Annotation->getNumOperands(); i++) {
+      if (auto Tuple = dyn_cast<MDTuple>(Annotation->getOperand(i))) {
+        for (int i = 0; i < Tuple->getNumOperands(); i++) {
+          if (auto stringMetadata = dyn_cast<MDString>(Tuple->getOperand(i))) {
+            if (stringMetadata->getString() == "alloca_name_altered") {
+              return ((MDString *)Tuple->getOperand(i + 1).get())->getString();
+            }
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fhahn wrote:

There should be an easy way to do this :) 

Might be good to use some early continues to reduce the nesting here.

https://github.com/llvm/llvm-project/pull/119387