Beginnings of MC-JIT code generation.

Proof-of-concept code that code-gens a module to an in-memory MachO object.
This will be hooked up to a run-time dynamic linker library (see: llvm-rtdyld
for similarly conceptual work for that part) which will take the compiled
object and link it together with the rest of the system, providing back to the
JIT a table of available symbols which will be used to respond to the
getPointerTo*() queries.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127916 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index 377f80d..a9e8045 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -224,11 +224,37 @@
 ///
 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM,
                                           MCContext *&Ctx,
+                                          raw_ostream &Out,
                                           CodeGenOpt::Level OptLevel,
                                           bool DisableVerify) {
   // Add common CodeGen passes.
   if (addCommonCodeGenPasses(PM, OptLevel, DisableVerify, Ctx))
     return true;
+
+  // Create the code emitter for the target if it exists.  If not, .o file
+  // emission fails.
+  MCCodeEmitter *MCE = getTarget().createCodeEmitter(*this, *Ctx);
+  TargetAsmBackend *TAB = getTarget().createAsmBackend(TargetTriple);
+  if (MCE == 0 || TAB == 0)
+    return true;
+
+  OwningPtr<MCStreamer> AsmStreamer;
+  AsmStreamer.reset(getTarget().createObjectStreamer(TargetTriple, *Ctx,
+                                                     *TAB, Out, MCE,
+                                                     hasMCRelaxAll(),
+                                                     hasMCNoExecStack()));
+  AsmStreamer.get()->InitSections();
+
+  // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
+  FunctionPass *Printer = getTarget().createAsmPrinter(*this, *AsmStreamer);
+  if (Printer == 0)
+    return true;
+
+  // If successful, createAsmPrinter took ownership of AsmStreamer.
+  AsmStreamer.take();
+
+  PM.add(Printer);
+
   // Make sure the code model is set.
   setCodeModelForJIT();