Subzero: Fixed deadlock with _start but no globals

src/IceASanInstrumentation.cpp

 //===- subzero/src/IceASanInstrumentation.cpp - ASan ------------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 56 matching lines @@
 bool ASanInstrumentation::isInstrumentable(Cfg *Func) {
   std::string FuncName = Func->getFunctionName().toStringOrEmpty();
   return FuncName == "" ||
          (FuncBlackList.count(FuncName) == 0 && FuncName.find(ASanPrefix) != 0);
 }
 
 // Create redzones around all global variables, ensuring that the initializer
 // types of the redzones and their associated globals match so that they are
 // laid out together in memory.
 void ASanInstrumentation::instrumentGlobals(VariableDeclarationList &Globals) {
+  std::unique_lock<std::mutex> _(GlobalsMutex);
   if (DidProcessGlobals)
     return;
   VariableDeclarationList NewGlobals;
   // Global holding pointers to all redzones
   auto *RzArray = VariableDeclaration::create(&NewGlobals);
   // Global holding sizes of all redzones
   auto *RzSizes = VariableDeclaration::create(&NewGlobals);
 
   RzArray->setName(Ctx, RzArrayName);
   RzSizes->setName(Ctx, RzSizesName);
@@ skipping 41 matching lines @@
     NewGlobals.push_back(RzLeft);
     NewGlobals.push_back(Global);
     NewGlobals.push_back(RzRight);
     RzGlobalsNum += 2;
   }
 
   // Replace old list of globals, without messing up arena allocators
   Globals.clear();
   Globals.merge(&NewGlobals);
   DidProcessGlobals = true;
-  GlobalsDoneCV.notify_all();
 
   // Log the new set of globals
   if (BuildDefs::dump() && (getFlags().getVerbose() & IceV_GlobalInit)) {
     OstreamLocker _(Ctx);
     Ctx->getStrDump() << "========= Instrumented Globals =========\n";
     for (VariableDeclaration *Global : Globals) {
       Global->dump(Ctx->getStrDump());
     }
   }
 }
@@ skipping 176 matching lines @@
 
 void ASanInstrumentation::instrumentStart(Cfg *Func) {
   Constant *ShadowMemInit =
       Ctx->getConstantExternSym(Ctx->getGlobalString("__asan_init"));
   constexpr SizeT NumArgs = 3;
   constexpr Variable *Void = nullptr;
   constexpr bool NoTailCall = false;
   auto *Call = InstCall::create(Func, NumArgs, Void, ShadowMemInit, NoTailCall);
   Func->getEntryNode()->getInsts().push_front(Call);
 
-  // wait to get the final count of global redzones
-  if (!DidProcessGlobals) {
-    GlobalsLock.lock();
-    while (!DidProcessGlobals)
-      GlobalsDoneCV.wait(GlobalsLock);
-    GlobalsLock.release();
-  }
+  instrumentGlobals(*getGlobals());
+
   Call->addArg(ConstantInteger32::create(Ctx, IceType_i32, RzGlobalsNum));
   Call->addArg(Ctx->getConstantSym(0, Ctx->getGlobalString(RzArrayName)));
   Call->addArg(Ctx->getConstantSym(0, Ctx->getGlobalString(RzSizesName)));
 }
 
 // TODO(tlively): make this more efficient with swap idiom
 void ASanInstrumentation::finishFunc(Cfg *) {
   ICE_TLS_GET_FIELD(LocalDtors)->clear();
 }
 
 } // end of namespace Ice