Ignore NaCl st_blksize of 0 and buffer writes to raw_fd_ostream.

src/main.cpp

 //===- subzero/src/main.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.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines a driver for translating PNaCl bitcode into native code.
@@ skipping 322 matching lines @@
   std::ofstream Ofs;
   switch (OutFileType) {
   case Ice::FT_Elf: {
     if (OutputFilename == "-") {
       *Ls << "Error: writing binary ELF to stdout is unsupported\n";
       return GetReturnValue(Ice::EC_Args);
     }
     std::error_code EC;
     raw_fd_ostream *FdOs =
         new raw_fd_ostream(OutputFilename, EC, sys::fs::F_None);
+    // NaCl sets st_blksize to 0, and LLVM uses that to pick the
+    // default preferred buffer size. Set to something non-zero.
+    FdOs->SetBufferSize(1 << 14);
     Os.reset(FdOs);
     if (EC) {
       *Ls << "Failed to open output file: " << OutputFilename << ":\n"
           << EC.message() << "\n";
       return GetReturnValue(Ice::EC_Args);
     }
     ELFStr.reset(new Ice::ELFStreamer(*FdOs));
   } break;
   case Ice::FT_Asm:
   case Ice::FT_Iasm: {
@@ skipping 60 matching lines @@
   if (SubzeroTimingEnabled)
     Ctx.dumpTimers();
   if (TimeEachFunction) {
     const bool DumpCumulative = false;
     Ctx.dumpTimers(Ice::GlobalContext::TSK_Funcs, DumpCumulative);
   }
   const bool FinalStats = true;
   Ctx.dumpStats("_FINAL_", FinalStats);
   return GetReturnValue(Ctx.getErrorStatus()->value());
 }