Subzero: Cleanly implement register allocation after phi lowering.

src/IceDefs.h

 //===- subzero/src/IceDefs.h - Common Subzero declarations ------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 179 matching lines @@
   /// deletes dead instructions (primarily stores).
   Liveness_Basic,
 
   /// In addition to Liveness_Basic, also calculate the complete
   /// live range for each variable in a form suitable for interference
   /// calculation and register allocation.
   Liveness_Intervals
 };
 
 enum RegAllocKind {
+  RAK_Unknown,
   RAK_Global, /// full, global register allocation
+  RAK_Phi,    /// infinite-weight Variables with active spilling/filling
   RAK_InfOnly /// allocation only for infinite-weight Variables
 };
 
 enum VerboseItem {
   IceV_None = 0,
   IceV_Instructions = 1 << 0,
   IceV_Deleted = 1 << 1,
   IceV_InstNumbers = 1 << 2,
   IceV_Preds = 1 << 3,
   IceV_Succs = 1 << 4,
@@ skipping 55 matching lines @@
 llvm::iterator_range<typename T::reverse_iterator> reverse_range(T &Container) {
   return llvm::make_range(Container.rbegin(), Container.rend());
 }
 
 /// Options for pooling and randomization of immediates.
 enum RandomizeAndPoolImmediatesEnum { RPI_None, RPI_Randomize, RPI_Pool };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEDEFS_H