Allow Subzero to parse function blocks in parallel.

src/IceCompiler.cpp

 //===- subzero/src/IceCompiler.cpp - Driver for bitcode translation -------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 45 matching lines @@
 }
 
 } // end of anonymous namespace
 
 void Compiler::run(const Ice::ClFlags &Flags, GlobalContext &Ctx,
                    std::unique_ptr<llvm::DataStreamer> &&InputStream) {
   // The Minimal build (specifically, when dump()/emit() are not implemented)
   // allows only --filetype=obj. Check here to avoid cryptic error messages
   // downstream.
   if (!BuildDefs::dump() && Ctx.getFlags().getOutFileType() != FT_Elf) {
-    // TODO(stichnot): Access the actual command-line argument via
-    // llvm::Option.ArgStr and .ValueStr .
     Ctx.getStrError()
         << "Error: only --filetype=obj is supported in this build.\n";
     Ctx.getErrorStatus()->assign(EC_Args);
     return;
   }
 
   TimerMarker T(Ice::TimerStack::TT_szmain, &Ctx);
 
   Ctx.emitFileHeader();
   Ctx.startWorkerThreads();
 
   std::unique_ptr<Translator> Translator;
   const IceString &IRFilename = Flags.getIRFilename();
   const bool BuildOnRead = Flags.getBuildOnRead() && !llvmIRInput(IRFilename);
   if (BuildOnRead) {
     std::unique_ptr<PNaClTranslator> PTranslator(new PNaClTranslator(&Ctx));
     std::unique_ptr<llvm::StreamingMemoryObject> MemObj(
         new llvm::StreamingMemoryObjectImpl(InputStream.release()));
     PTranslator->translate(IRFilename, std::move(MemObj));
     Translator.reset(PTranslator.release());
   } else if (BuildDefs::llvmIr()) {
     if (BuildDefs::browser()) {
       Ctx.getStrError()
           << "non BuildOnRead is not supported w/ PNACL_BROWSER_TRANSLATOR\n";
       Ctx.getErrorStatus()->assign(EC_Args);
+      Ctx.waitForWorkerThreads();
       return;
     }
     // Globals must be kept alive after lowering when converting from LLVM to
     // Ice.
     Ctx.setDisposeGlobalVariablesAfterLowering(false);
     // Parse the input LLVM IR file into a module.
     llvm::SMDiagnostic Err;
     TimerMarker T1(Ice::TimerStack::TT_parse, &Ctx);
     llvm::DiagnosticHandlerFunction DiagnosticHandler =
         Flags.getLLVMVerboseErrors()
             ? redirectNaClDiagnosticToStream(llvm::errs())
             : nullptr;
     std::unique_ptr<llvm::Module> Mod =
         NaClParseIRFile(IRFilename, Flags.getInputFileFormat(), Err,
                         llvm::getGlobalContext(), DiagnosticHandler);
     if (!Mod) {
       Err.print(Flags.getAppName().c_str(), llvm::errs());
       Ctx.getErrorStatus()->assign(EC_Bitcode);
+      Ctx.waitForWorkerThreads();
       return;
     }
 
     std::unique_ptr<Converter> Converter(new class Converter(Mod.get(), &Ctx));
     Converter->convertToIce();
     Translator.reset(Converter.release());
   } else {
     Ctx.getStrError() << "Error: Build doesn't allow LLVM IR, "
                       << "--build-on-read=0 not allowed\n";
     Ctx.getErrorStatus()->assign(EC_Args);
+    Ctx.waitForWorkerThreads();
     return;
   }
 
   Ctx.waitForWorkerThreads();
   if (Translator->getErrorStatus()) {
     Ctx.getErrorStatus()->assign(Translator->getErrorStatus().value());
   } else {
     Ctx.lowerGlobals("last");
     Ctx.lowerProfileData();
     Ctx.lowerConstants();
@@ skipping 11 matching lines @@
 
   if (Ctx.getFlags().getTimeEachFunction()) {
     constexpr bool NoDumpCumulative = false;
     Ctx.dumpTimers(GlobalContext::TSK_Funcs, NoDumpCumulative);
   }
   constexpr bool FinalStats = true;
   Ctx.dumpStats("_FINAL_", FinalStats);
 }
 
 } // end of namespace Ice