Subzero: Add locking to prepare for multithreaded translation.

src/PNaClTranslator.cpp

Index: src/PNaClTranslator.cpp
diff --git a/src/PNaClTranslator.cpp b/src/PNaClTranslator.cpp
index beb4e22922f56d7001f6622b8887ed8cc5406925..a405d8b25c5425ad0f25cb390f5b87301283d89c 100644
--- a/src/PNaClTranslator.cpp
+++ b/src/PNaClTranslator.cpp
@@ -166,6 +166,11 @@ public:
       : 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());
   }
 
@@ -2814,8 +2819,7 @@ private:
       Decl->setName(Trans.createUnnamedName(Prefix, NameIndex));
       ++NameIndex;
     } else {
-      Trans.checkIfUnnamedNameSafe(Decl->getName(), Context, Prefix,
-                                   Trans.getContext()->getStrDump());
+      Trans.checkIfUnnamedNameSafe(Decl->getName(), Context, Prefix);
     }
   }