Allows allocation of LR on ARM.

runtime/vm/constants_arm.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_CONSTANTS_ARM_H_
 #define VM_CONSTANTS_ARM_H_
 
 #include "platform/globals.h"
 #include "platform/assert.h"
 
@@ skipping 19 matching lines @@
   kFirstFreeCpuRegister = 0,
   R0  =  0,
   R1  =  1,
   R2  =  2,
   R3  =  3,
   R4  =  4,
   R5  =  5,
   R6  =  6,
   R7  =  7,
   R8  =  8,
-  kLastFreeCpuRegister = 8,
-  R9  =  9,
-  R10 = 10,
-  R11 = 11,
-  R12 = 12,
-  R13 = 13,
-  R14 = 14,
-  R15 = 15,
+  R9  =  9,  // CTX
+  R10 = 10,  // PP
+  R11 = 11,  // FP
+  R12 = 12,  // IP
+  R13 = 13,  // SP
+  R14 = 14,  // LR
+  kLastFreeCpuRegister = 14,
+  R15 = 15,  // PC
   FP  = 11,
   IP  = 12,
   SP  = 13,
   LR  = 14,
   PC  = 15,
   kNumberOfCpuRegisters = 16,
 };
 
 
 // Values for single-precision floating point registers.
@@ skipping 638 matching lines @@
   static Instr* At(uword pc) { return reinterpret_cast<Instr*>(pc); }
 
  private:
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Instr);
 };
 
 }  // namespace dart
 
 #endif  // VM_CONSTANTS_ARM_H_