Subzero: Initial implementation of multithreaded translation.

src/IceClFlags.h

Index: src/IceClFlags.h
diff --git a/src/IceClFlags.h b/src/IceClFlags.h
index b444dc05c1964d210523ea9442894bfd14ff1ae0..d2c0243111a86f03baa4b44117dc15d679db21fb 100644
--- a/src/IceClFlags.h
+++ b/src/IceClFlags.h
@@ -28,8 +28,9 @@ public:
         DumpStats(false), AllowUninitializedGlobals(false),
         TimeEachFunction(false), DisableIRGeneration(false),
         AllowErrorRecovery(false), GenerateUnitTestMessages(false),
-        DefaultGlobalPrefix(""), DefaultFunctionPrefix(""), TimingFocusOn(""),
-        VerboseFocusOn(""), TranslateOnly("") {}
+        NumTranslationThreads(0), DefaultGlobalPrefix(""),
+        DefaultFunctionPrefix(""), TimingFocusOn(""), VerboseFocusOn(""),
+        TranslateOnly("") {}
   bool DisableInternal;
   bool SubzeroTimingEnabled;
   bool DisableTranslation;
@@ -46,6 +47,7 @@ public:
   bool DisableIRGeneration;
   bool AllowErrorRecovery;
   bool GenerateUnitTestMessages;
+  size_t NumTranslationThreads; // 0 means completely sequential
   IceString DefaultGlobalPrefix;
   IceString DefaultFunctionPrefix;
   IceString TimingFocusOn;