[ASAN] Add doFinalization to reset state

[loladiro]

Summary

If the same pass manager is used for multiple modules ASAN complains about GlobalsMD being initialized twice. Fix this by resetting GlobalsMD in a new doFinalization method to allow this use case.

[kcc]

Is a test possible for this fix?

[loladiro]

The easiest thing would probably be to change llc to reuse the pass manager if multiple modules are passed on the command line. Then this could be tested quite easily from the command line. Will draw up an appropriate patch and see if people like it.

[loladiro]

Add test case

[kcc]

LGTM,
but I would run this test on a non-empty test (with some small function in it), just in case.

lib/Transforms/Instrumentation/AddressSanitizer.cpp

struct Entry {
     LocationMetadata SourceLoc;
     StringRef Name;
     bool IsDynInit;
     bool IsBlacklisted;
   };
 
   GlobalsMetadata() : inited_(false) {}
 
+  void reset() {
+    inited_ = false;
+    Entries.clear();
+  }
+
   void init(Module &M) {
     assert(!inited_);
     inited_ = true;
     NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
     if (!Globals) return;
     for (auto MDN : Globals->operands()) {
       // Metadata node contains the global and the fields of "Entry".
       assert(MDN->getNumOperands() == 5);
Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
                                  bool IsWrite, size_t AccessSizeIndex,
                                  Value *SizeArgument, uint32_t Exp);
   void instrumentMemIntrinsic(MemIntrinsic *MI);
   Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
   bool runOnFunction(Function &F) override;
   bool maybeInsertAsanInitAtFunctionEntry(Function &F);
   void markEscapedLocalAllocas(Function &F);
   bool doInitialization(Module &M) override;
+  bool doFinalization(Module &M) override;
   static char ID;  // Pass identification, replacement for typeid
 
   DominatorTree &getDominatorTree() const { return *DT; }
 
  private:
   void initializeCallbacks(Module &M);
 
   bool LooksLikeCodeInBug11395(Instruction *I);
std::tie(AsanCtorFunction, AsanInitFunction) =
             M, kAsanModuleCtorName, kAsanInitName,
             /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
     appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
   }
   Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
   return true;
 }
 
+bool AddressSanitizer::doFinalization(Module &M) {
+  GlobalsMD.reset();
+  return false;
+}
+
 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
   // For each NSObject descendant having a +load method, this method is invoked
   // by the ObjC runtime before any of the static constructors is called.
   // Therefore we need to instrument such methods with a call to __asan_init
   // at the beginning in order to initialize our runtime before any access to
   // the shadow memory.
   // We cannot just ignore these methods, because they may call other
   // instrumented functions.

test/Transforms/AddressSanitizer/empty-twice.ll

+; Check that the address sanitizer pass can be reused
+; RUN: opt < %s -S -run-twice -asan