[compiler-rt] [llvm] [msan] Add experimental '-mllvm -msan-embed-faulting-instruction' and MSAN_OPTIONS=print_faulting_instruction (PR #136539)

[Florian Mayer via llvm-commits]

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@@ -1455,21 +1513,51 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
     // correct origin.
     bool Combine = !MS.TrackOrigins;
     Instruction *Instruction = InstructionChecks.front().OrigIns;
+
+    Value *InstName = nullptr;
+    if (ClEmbedFaultingInst >= 1) {
+      IRBuilder<> IRB0(Instruction);
+      std::string str;
+      StringRef InstNameStrRef;
+
+      // Dumping the full instruction is expensive because the operands etc.
+      // likely make the string unique per instruction instance, hence we
+      // offer a choice whether to only print the instruction name.
+      if (ClEmbedFaultingInst >= 2) {
+        llvm::raw_string_ostream buf(str);
+        Instruction->print(buf);
+        InstNameStrRef = StringRef(str);
+      } else if (ClEmbedFaultingInst >= 1) {
+        if (CallInst *CI = dyn_cast<CallInst>(Instruction)) {
+          if (CI->getCalledFunction()) {
+            Twine description = "call " + CI->getCalledFunction()->getName();
+            SmallVector<char> maybeBuf;
+            InstNameStrRef = description.toStringRef(maybeBuf);
+          } else {
+            InstNameStrRef = StringRef("Unknown call");
+          }
+        } else {
+          InstNameStrRef = StringRef(Instruction->getOpcodeName());
+        }
+      }
+
+      InstName = IRB0.CreateGlobalString(InstNameStrRef);
+    }
+
     Value *Shadow = nullptr;
     for (const auto &ShadowData : InstructionChecks) {
       assert(ShadowData.OrigIns == Instruction);
       IRBuilder<> IRB(Instruction);
 
       Value *ConvertedShadow = ShadowData.Shadow;
-
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fmayer wrote:

unrelated change

https://github.com/llvm/llvm-project/pull/136539