Codegen pass definition cleanup. No functionality.

Moving toward a uniform style of pass definition to allow easier target configuration.
Globally declare Pass ID.
Globally declare pass initializer.
Use INITIALIZE_PASS consistently.
Add a call to the initializer from CodeGen.cpp.
Remove redundant "createPass" functions and "getPassName" methods.

While cleaning up declarations, cleaned up comments (sorry for large diff).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150100 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineCopyPropagation.cpp b/lib/CodeGen/MachineCopyPropagation.cpp
index 17343cd..ed3f349 100644
--- a/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/lib/CodeGen/MachineCopyPropagation.cpp
@@ -50,14 +50,11 @@
   };
 }
 char MachineCopyPropagation::ID = 0;
+char &llvm::MachineCopyPropagationID = MachineCopyPropagation::ID;
 
 INITIALIZE_PASS(MachineCopyPropagation, "machine-cp",
                 "Machine Copy Propagation Pass", false, false)
 
-FunctionPass *llvm::createMachineCopyPropagationPass() {
-  return new MachineCopyPropagation();
-}
-
 void
 MachineCopyPropagation::SourceNoLongerAvailable(unsigned Reg,
                               DenseMap<unsigned, unsigned> &SrcMap,