Starting to refactor Target to separate out code that's needed to fully describe
target machine from those that are only needed by codegen. The goal is to
sink the essential target description into MC layer so we can start building
MC based tools without needing to link in the entire codegen.

First step is to refactor TargetRegisterInfo. This patch added a base class
MCRegisterInfo which TargetRegisterInfo is derived from. Changed TableGen to
separate register description from the rest of the stuff.

llvm-svn: 133782
diff --git a/llvm/lib/Target/X86/TargetDesc/X86TargetDesc.cpp b/llvm/lib/Target/X86/TargetDesc/X86TargetDesc.cpp
new file mode 100644
index 0000000..cf03d48
--- /dev/null
+++ b/llvm/lib/Target/X86/TargetDesc/X86TargetDesc.cpp
@@ -0,0 +1,23 @@
+//===-- X86TargetDesc.cpp - X86 Target Descriptions -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides X86 specific target descriptions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "X86TargetDesc.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "X86GenRegisterDesc.inc"
+using namespace llvm;
+
+MCRegisterInfo *createX86MCRegisterInfo() {
+  MCRegisterInfo *X = new MCRegisterInfo();
+  InitX86MCRegisterInfo(X);
+  return X;
+}