Bitcode streaming

lib/Bitcode/Reader/BitcodeStream.cpp

Index: lib/Bitcode/Reader/BitcodeStream.cpp
diff --git a/lib/Bitcode/Reader/BitcodeStream.cpp b/lib/Bitcode/Reader/BitcodeStream.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7206dbad6abc21ac81745e91a5efda8302648ed8
--- /dev/null
+++ b/lib/Bitcode/Reader/BitcodeStream.cpp
@@ -0,0 +1,52 @@
+//===---- llvm/Bitcode/Reader/BitcodeStream.cpp -  ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Support for streaming (lazy reading) of bitcode files on disk
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Bitcode/BitcodeStream.h"
+#include "llvm/Support/SourceMgr.h"
+#include <string>
+#include <cerrno>
+#include <cstdio>
+
+namespace {
+class FileStream {
+ FILE *Fd;
+ public:
+ FileStream() : Fd(NULL) {}
+ size_t FileGetBytes(unsigned char *buf, size_t len) {
+  return fread(buf, 1, len, Fd);
+ }
+
+ bool OpenFileStream(const std::string &Filename) {
+  Fd = fopen(Filename.c_str(), "r");
+  return Fd != NULL;
+ }
+};
+
+static FileStream *stream;
+size_t FileStreamCallback(unsigned char *buf, size_t len) {
+  return stream->FileGetBytes(buf, len);
+}
+}
+
+namespace llvm {
+StreamChunkCallback GetBitcodeFileStream(const std::string &Filename,
+                                         SMDiagnostic &Err) {
+  stream = new FileStream();
+  if (!stream->OpenFileStream(Filename)) {
+    Err = SMDiagnostic(Filename, SourceMgr::DK_Error,
+                       "Could not open input file");
+    return NULL;
+  }
+  return FileStreamCallback;
+}
+}