Implement LLVM JIT side of GDB JIT debugging interface

lib/Target/TargetMachine.cpp

Index: lib/Target/TargetMachine.cpp
===================================================================
--- lib/Target/TargetMachine.cpp	(revision 82403)
+++ lib/Target/TargetMachine.cpp	(working copy)
@@ -35,6 +35,7 @@
   bool NoZerosInBSS;
   bool DwarfExceptionHandling;
   bool SjLjExceptionHandling;
+  bool JITEmitDebugInfo;
   bool UnwindTablesMandatory;
   Reloc::Model RelocationModel;
   CodeModel::Model CMModel;
@@ -114,7 +115,19 @@
   cl::desc("Emit SJLJ exception handling (default if target supports)"),
   cl::location(SjLjExceptionHandling),
   cl::init(false));
+// In debug builds, make this default to true.
+#ifdef NDEBUG
+#define EMIT_DEBUG false
+#else
+#define EMIT_DEBUG true
+#endif
 static cl::opt<bool, true>
+EmitJitDebugInfo("jit-emit-debug",
+  cl::desc("Emit debug information to debugger"),
+  cl::location(JITEmitDebugInfo),
+  cl::init(EMIT_DEBUG));
+#undef EMIT_DEBUG
+static cl::opt<bool, true>
 EnableUnwindTables("unwind-tables",
   cl::desc("Generate unwinding tables for all functions"),
   cl::location(UnwindTablesMandatory),
@@ -243,4 +256,3 @@
     return !UnsafeFPMath && HonorSignDependentRoundingFPMathOption;
   }
 }
-