[CodeGen] Split SafeStack into a LegacyPass and a utility. NFC.

This lets the pass focus on gathering the required analyzes, and the
utility class focus on the transformation.

Differential Revision: https://reviews.llvm.org/D31303

llvm-svn: 302609

llvm/lib/CodeGen/CodeGen.cpp

@@ -79,7 +79,7 @@ void llvm::initializeCodeGen(PassRegistry &Registry) {
   initializeRAGreedyPass(Registry);
   initializeRegisterCoalescerPass(Registry);
   initializeRenameIndependentSubregsPass(Registry);
-  initializeSafeStackPass(Registry);
+  initializeSafeStackLegacyPassPass(Registry);
   initializeShrinkWrapPass(Registry);
   initializeSlotIndexesPass(Registry);
   initializeStackColoringPass(Registry);