Subzero: Use the linear-scan register allocator for Om1 as well.

src/IceDefs.h

 //===- subzero/src/IceDefs.h - Common Subzero declaraions -------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares various useful types and classes that have
@@ skipping 84 matching lines @@
   // live-in and live-out variables for each block.  Identifies and
   // 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_Global, // full, global register allocation
+  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,
   IceV_RegManager = 1 << 6,
   IceV_RegOrigins = 1 << 7,
   IceV_LinearScan = 1 << 8,
   IceV_Frame = 1 << 9,
   IceV_AddrOpt = 1 << 10,
   IceV_All = ~IceV_None,
   IceV_Most = IceV_All & ~IceV_LinearScan
 };
 typedef uint32_t VerboseMask;
 
 typedef llvm::raw_ostream Ostream;
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEDEFS_H