Add support to the JIT for true non-lazy operation. When a call to a function

that has not been JIT'd yet, the callee is put on a list of pending functions
to JIT.  The call is directed through a stub, which is updated with the address
of the function after it has been JIT'd.  A new interface for allocating and
updating empty stubs is provided.

Add support for removing the ModuleProvider the JIT was created with, which
would otherwise invalidate the JIT's PassManager, which is initialized with the
ModuleProvider's Module.

Add support under a new ExecutionEngine flag for emitting the infomration 
necessary to update Function and GlobalVariable stubs after JITing them, by
recording the address of the stub and the name of the GlobalValue.  This allows
code to be copied from one address space to another, where libraries may live
at different virtual addresses, and have the stubs updated with their new
correct target addresses.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64906 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineCodeEmitter.h

@@ -82,6 +82,13 @@ public:
   virtual void startGVStub(const GlobalValue* GV, unsigned StubSize,
                            unsigned Alignment = 1) = 0;
 
+  /// startGVStub - This callback is invoked when the JIT needs the address of a 
+  /// GV (e.g. function) that has not been code generated yet.  Buffer points to
+  /// memory already allocated for this stub.
+  ///
+  virtual void startGVStub(const GlobalValue* GV, void *Buffer,
+                           unsigned StubSize) = 0;
+  
   /// finishGVStub - This callback is invoked to terminate a GV stub.
   ///
   virtual void *finishGVStub(const GlobalValue* F) = 0;