Fix the PNaCl translator to lock the dump stream when printing errors.

src/PNaClTranslator.cpp

 //===- subzero/src/PNaClTranslator.cpp - ICE from bitcode -----------------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the PNaCl bitcode file to Ice, to machine code
@@ skipping 147 matching lines @@
   TopLevelParser(const TopLevelParser &) = delete;
   TopLevelParser &operator=(const TopLevelParser &) = delete;
 
 public:
   typedef std::vector<Ice::FunctionDeclaration *> FunctionDeclarationListType;
 
   TopLevelParser(Ice::Translator &Translator, NaClBitcodeHeader &Header,
                  NaClBitstreamCursor &Cursor, bool &ErrorStatus)
       : NaClBitcodeParser(Cursor), Translator(Translator), Header(Header),
         ErrorStatus(ErrorStatus), NumErrors(0), NumFunctionIds(0),
-        NumFunctionBlocks(0), BlockParser(nullptr) {
-    // Note: This gives the reader uncontrolled access to the dump
-    // stream, which it can then use without locking.  TODO(kschimpf):
-    // Consider reworking the LLVM side to use e.g. a callback for
-    // errors.
-    Ice::OstreamLocker L(Translator.getContext());
-    setErrStream(Translator.getContext()->getStrDump());
-  }
+        NumFunctionBlocks(0), BlockParser(nullptr) {}
 
   ~TopLevelParser() override {}
 
   Ice::Translator &getTranslator() { return Translator; }
 
   void setBlockParser(BlockParserBaseClass *NewBlockParser) {
     BlockParser = NewBlockParser;
   }
 
   // Generates error with given Message. Always returns true.
@@ skipping 244 matching lines @@
   Ice::VariableDeclaration *reportGetGlobalVariableByIDError(unsigned Index);
 
   // Reports that there is no corresponding ICE type for LLVMTy, and
   // returns ICE::IceType_void.
   Ice::Type convertToIceTypeError(Type *LLVMTy);
 };
 
 bool TopLevelParser::Error(const std::string &Message) {
   ErrorStatus = true;
   ++NumErrors;
+  Ice::GlobalContext *Context = Translator.getContext();
+  Ice::OstreamLocker L(Context);
+  raw_ostream *OldErrStream = setErrStream(Context->getStrDump());
   NaClBitcodeParser::Error(Message);
+  setErrStream(*OldErrStream);
   if (!Translator.getFlags().AllowErrorRecovery)
     report_fatal_error("Unable to continue");
   return true;
 }
 
 void TopLevelParser::reportBadTypeIDAs(unsigned ID, const ExtendedType *Ty,
                                        ExtendedType::TypeKind WantedType) {
   std::string Buffer;
   raw_string_ostream StrBuf(Buffer);
   if (Ty == nullptr) {
@@ skipping 2551 matching lines @@
 
   if (TopLevelBlocks != 1) {
     errs() << IRFilename
            << ": Contains more than one module. Found: " << TopLevelBlocks
            << "\n";
     ErrorStatus = true;
   }
 }
 
 } // end of namespace Ice