[ThinLTO] Refactor module loader handling into new LTO file (NFC)

Moved the ModuleLoader and supporting helper loadModuleFromBuffer out of
ThinLTOCodeGenerator and into new LTO.h/LTO.cpp files. This is in
preparation for a patch that will utilize these in the gold-plugin.

Note that there are some other pending patches (D20268 and D20290) that
also plan to refactor common interfaces and functionality into this same
pair of new files.

llvm-svn: 270509

1 files changed, 42 insertions, 0 deletions

diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
new file mode 100644
index 0000000..5f89e5c
--- /dev/null
+++ b/llvm/lib/LTO/LTO.cpp
@@ -0,0 +1,42 @@
+//===-LTO.cpp - LLVM Link Time Optimizer ----------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements functions and classes used to support LTO.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/LTO/LTO.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace llvm {
+
+// Simple helper to load a module from bitcode
+std::unique_ptr<Module> loadModuleFromBuffer(const MemoryBufferRef &Buffer,
+                                             LLVMContext &Context, bool Lazy) {
+  SMDiagnostic Err;
+  ErrorOr<std::unique_ptr<Module>> ModuleOrErr(nullptr);
+  if (Lazy) {
+    ModuleOrErr =
+        getLazyBitcodeModule(MemoryBuffer::getMemBuffer(Buffer, false), Context,
+                             /* ShouldLazyLoadMetadata */ Lazy);
+  } else {
+    ModuleOrErr = parseBitcodeFile(Buffer, Context);
+  }
+  if (std::error_code EC = ModuleOrErr.getError()) {
+    Err = SMDiagnostic(Buffer.getBufferIdentifier(), SourceMgr::DK_Error,
+                       EC.message());
+    Err.print("ThinLTO", errs());
+    report_fatal_error("Can't load module, abort.");
+  }
+  return std::move(ModuleOrErr.get());
+}
+}