Add support to the X86 backend for emitting ELF files. To use this, we

currently use: llc t.bc --filetype=obj

This will produce a t.o file which is dumpable with readelf.  Currently
the file produced is empty, but the scaffolding to do more is now in place.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22292 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86ELFWriter.cpp

@@ -0,0 +1,34 @@
+//===-- X86ELFWriter.cpp - Emit an ELF file for the X86 backend -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements an ELF writer for the X86 backend.  The public interface
+// to this file is the createX86ELFObjectWriterPass function.
+//
+//===----------------------------------------------------------------------===//
+
+#include "X86.h"
+#include "llvm/CodeGen/ELFWriter.h"
+using namespace llvm;
+
+namespace {
+  class X86ELFWriter : public ELFWriter {
+  public:
+    X86ELFWriter(std::ostream &O, TargetMachine &TM) : ELFWriter(O, TM) {
+      e_machine = 3;   // EM_386
+    }
+  };
+}
+
+/// createX86ELFObjectWriterPass - Returns a pass that outputs the generated
+/// code as an ELF object file.
+///
+FunctionPass *llvm::createX86ELFObjectWriterPass(std::ostream &O,
+                                                 TargetMachine &TM) {
+  return new X86ELFWriter(O, TM);
+}