Subzero: Fixed deadlock with _start but no globals

src/IceASanInstrumentation.h

 //===- subzero/src/IceASanInstrumentation.h - AddressSanitizer --*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 15 matching lines @@
 #include <condition_variable>
 
 namespace Ice {
 
 class ASanInstrumentation : public Instrumentation {
   ASanInstrumentation() = delete;
   ASanInstrumentation(const ASanInstrumentation &) = delete;
   ASanInstrumentation &operator=(const ASanInstrumentation &) = delete;
 
 public:
-  ASanInstrumentation(GlobalContext *Ctx)
-      : Instrumentation(Ctx), RzNum(0),
-        GlobalsLock(GlobalsMutex, std::defer_lock) {
+  ASanInstrumentation(GlobalContext *Ctx) : Instrumentation(Ctx), RzNum(0) {
     ICE_TLS_INIT_FIELD(LocalDtors);
   }
   void instrumentGlobals(VariableDeclarationList &Globals) override;
 
 private:
   std::string nextRzName();
   bool isInstrumentable(Cfg *Func) override;
   void instrumentFuncStart(LoweringContext &Context) override;
   void instrumentCall(LoweringContext &Context, InstCall *Instr) override;
   void instrumentRet(LoweringContext &Context, InstRet *Instr) override;
   void instrumentLoad(LoweringContext &Context, InstLoad *Instr) override;
   void instrumentStore(LoweringContext &Context, InstStore *Instr) override;
   void instrumentAccess(LoweringContext &Context, Operand *Op, SizeT Size,
                         Constant *AccessFunc);
   void instrumentStart(Cfg *Func) override;
   void finishFunc(Cfg *Func) override;
   ICE_TLS_DECLARE_FIELD(std::vector<InstCall *> *, LocalDtors);
   std::atomic<uint32_t> RzNum;
   bool DidProcessGlobals = false;
   SizeT RzGlobalsNum = 0;
   std::mutex GlobalsMutex;
-  std::unique_lock<std::mutex> GlobalsLock;
-  std::condition_variable GlobalsDoneCV;
 };
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEASANINSTRUMENTATION_H