Fix pnacl-sz to return with staus 0 in report_fatal_error.

src/IceCompileServer.cpp

 //===- subzero/src/IceCompileServer.cpp - Compile server ------------------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 75 matching lines @@
         new llvm::raw_fd_ostream(Filename, EC, llvm::sys::fs::F_None));
   }
 }
 
 ErrorCodes getReturnValue(const Ice::ClFlagsExtra &Flags, ErrorCodes Val) {
   if (Flags.getAlwaysExitSuccess())
     return EC_None;
   return Val;
 }
 
+// Reports fatal error message, and then exits with success status 0.
+void reportFatalErrorThenExitSuccess(void * UserData,
+                                     const std::string &Reason,
+                                     bool GenCrashDag) {
+  (void)UserData;
+  (void)GenCrashDag;
+
+  // Note: This code is (mostly) copied from llvm/lib/Support/ErrorHandling.cpp
+
+  // Blast the result out to stderr.  We don't try hard to make sure this
+  // succeeds (e.g. handling EINTR) and we can't use errs() here because
+  // raw ostreams can call report_fatal_error.
+  llvm::SmallVector<char, 64> Buffer;
+  llvm::raw_svector_ostream OS(Buffer);
+  OS << "LLVM ERROR: " << Reason << "\n";
+  llvm::StringRef MessageStr = OS.str();
+  ssize_t written = ::write(2, MessageStr.data(), MessageStr.size());
+  (void)written; // If something went wrong, we deliberately just give up.
+
+  // If we reached here, we are failing ungracefully. Run the interrupt handlers
+  // to make sure any special cleanups get done, in particular that we remove
+  // files registered with RemoveFileOnSignal.
+  llvm::sys::RunInterruptHandlers();
+
+  exit(0);
+}
+
 } // end of anonymous namespace
 
 void CLCompileServer::run() {
   if (BuildDefs::dump()) {
     llvm::sys::PrintStackTraceOnErrorSignal();
   }
   ClFlags::parseFlags(argc, argv);
   ClFlags Flags;
   ClFlagsExtra ExtraFlags;
   ClFlags::getParsedClFlags(Flags);
   ClFlags::getParsedClFlagsExtra(ExtraFlags);
 
+  // Override report_fatal_error if we want to exit with 0 status.
+  if (ExtraFlags.getAlwaysExitSuccess())
+    llvm::install_fatal_error_handler(reportFatalErrorThenExitSuccess, this);
+
   std::error_code EC;
   std::unique_ptr<Ostream> Ls = makeStream(ExtraFlags.getLogFilename(), EC);
   if (EC) {
     llvm::report_fatal_error("Unable to open log file");
   }
   Ls->SetUnbuffered();
   std::unique_ptr<Ostream> Os;
   std::unique_ptr<ELFStreamer> ELFStr;
   switch (Flags.getOutFileType()) {
   case FT_Elf: {
@@ skipping 51 matching lines @@
     });
     CompileThread.join();
   } else {
     getCompiler().run(ExtraFlags, *Ctx.get(), std::move(InputStream));
   }
   transferErrorCode(getReturnValue(
       ExtraFlags, static_cast<ErrorCodes>(Ctx->getErrorStatus()->value())));
 }
 
 } // end of namespace Ice