Refactor Subzero initialization and add a browser callback handler.

src/IceBrowserCompileServer.h

+//===- subzero/src/IceBrowserCompileServer.h - Browser server ---*- C++ -*-===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the browser-specific compile server.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUBZERO_SRC_ICEBROWSERCOMPILESERVER_H
+#define SUBZERO_SRC_ICEBROWSERCOMPILESERVER_H
+
+#include <thread>
+
+#include "IceClFlags.h"
+#include "IceClFlagsExtra.h"
+#include "IceCompileServer.h"
+#include "IceDefs.h"
+#include "IceELFStreamer.h"
+
+namespace llvm {
+class QueueStreamer;
+class raw_fd_ostream;
+};
+
+namespace Ice {
+
+// The browser variant of the compile server.
+// Compared to the commandline version, this version gets compile
+// requests over IPC. Each compile request will have a slimmed down
+// version of argc, argv while other flags are set to defaults that
+// make sense in the browser case. The output file is specified via
+// a posix FD, and input bytes are pushed to the server.
+class BrowserCompileServer : public CompileServer {
+  BrowserCompileServer() = delete;
+  BrowserCompileServer(const BrowserCompileServer &) = delete;
+  BrowserCompileServer &operator=(const BrowserCompileServer &) = delete;
+
+public:
+  explicit BrowserCompileServer(Compiler &Comp)
+      : CompileServer(Comp), InputStream(nullptr) {}
+
+  ~BrowserCompileServer() final;
+
+  void run() final;
+
+  // Parse and set up the flags for compile jobs.
+  void getParsedFlags(uint32_t NumThreads, int argc, char **argv);
+
+  // Creates the streams + context and starts the compile thread,
+  // handing off the streams + context.
+  void startCompileThread(int OutFD);
+
+  // Call to push more bytes to the current input stream.
+  // Returns false on success and true on error.
+  bool pushInputBytes(const void *Data, size_t NumBytes);
+
+  // Notify the input stream of EOF.
+  void endInputStream();
+
+  // Wait for the compile thread to complete then reset the state.
+  void waitForCompileThread() {
+    CompileThread.join();
+    LastError.assign(Ctx->getErrorStatus()->value());
+    // Reset some state. The InputStream is deleted by the compiler
+    // so only reset this to nullptr. Free and flush the rest
+    // of the streams.
+    InputStream = nullptr;
+    EmitStream.reset(nullptr);
+    ELFStream.reset(nullptr);
+  }
+
+private:
+  // This currently only handles a single compile request, hence one copy
+  // of the state.
+  std::unique_ptr<GlobalContext> Ctx;
+  // A borrowed reference to the current InputStream. The compiler owns
+  // the actual reference so the server must be careful not to access
+  // after the compiler is done.
+  llvm::QueueStreamer *InputStream;
+  std::unique_ptr<Ostream> LogStream;
+  std::unique_ptr<llvm::raw_fd_ostream> EmitStream;
+  std::unique_ptr<ELFStreamer> ELFStream;
+  ClFlags Flags;
+  ClFlagsExtra ExtraFlags;
+  std::thread CompileThread;
+};
+
+} // end of namespace Ice
+
+#endif // SUBZERO_SRC_ICEBROWSERCOMPILESERVER_H