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
diff --git a/lib/Target/X86/X86TargetMachine.cpp b/lib/Target/X86/X86TargetMachine.cpp
index dcf27ac..2330182 100644
--- a/lib/Target/X86/X86TargetMachine.cpp
+++ b/lib/Target/X86/X86TargetMachine.cpp
@@ -98,7 +98,8 @@
 // does to emit statically compiled machine code.
 bool X86TargetMachine::addPassesToEmitFile(PassManager &PM, std::ostream &Out,
                                            CodeGenFileType FileType) {
-  if (FileType != TargetMachine::AssemblyFile) return true;
+  if (FileType != TargetMachine::AssemblyFile && 
+      FileType != TargetMachine::ObjectFile) return true;
 
   // FIXME: Implement efficient support for garbage collection intrinsics.
   PM.add(createLowerGCPass());
@@ -146,7 +147,19 @@
     PM.add(createX86CodePrinterPass(std::cerr, *this));
 
   if (!DisableOutput)
-    PM.add(createX86CodePrinterPass(Out, *this));
+    switch (FileType) {
+    default:
+      assert(0 && "Unexpected filetype here!");
+    case TargetMachine::AssemblyFile:
+      PM.add(createX86CodePrinterPass(Out, *this));
+      break;
+    case TargetMachine::ObjectFile:
+      // FIXME: We only support emission of ELF files for now, this should check
+      // the target triple and decide on the format to write (e.g. COFF on
+      // win32).
+      PM.add(createX86ELFObjectWriterPass(Out, *this));
+      break;
+    }
 
   // Delete machine code for this function
   PM.add(createMachineCodeDeleter());