Subzero: Implement "second-chance bin-packing" for register allocation.

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 199 matching lines @@
   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
+  RAK_Global,       /// full, global register allocation
+  RAK_SecondChance, /// second-chance bin-packing after full regalloc attempt
+  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,
   IceV_Liveness = 1 << 5,
@@ skipping 67 matching lines @@
   RPE_GlobalVariableReordering,
   RPE_NopInsertion,
   RPE_PooledConstantReordering,
   RPE_RegAllocRandomization,
   RPE_num
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEDEFS_H