Adds debugger patching to arm64.

runtime/vm/constants_arm64.h

 // Copyright (c) 2014, 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_ARM64_H_
 #define VM_CONSTANTS_ARM64_H_
 
 #include "platform/assert.h"
 
 namespace dart {
@@ skipping 592 matching lines @@
   kImm3Shift = 10,
   kImm3Bits = 3,
   kImm6Shift = 10,
   kImm6Bits = 6,
   kImm8Shift = 13,
   kImm8Bits = 8,
   kImm9Shift = 12,
   kImm9Bits = 9,
   kImm12Shift = 10,
   kImm12Bits = 12,
+  kImm12Mask = 0xfff << kImm12Shift,
   kImm12ShiftShift = 22,
   kImm12ShiftBits = 2,
   kImm14Shift = 5,
   kImm14Bits = 14,
   kImm16Shift = 5,
   kImm16Bits = 16,
   kImm16Mask = 0xffff << kImm16Shift,
   kImm19Shift = 5,
   kImm19Bits = 19,
   kImm19Mask = 0x7ffff << kImm19Shift,
@@ skipping 117 matching lines @@
         (static_cast<int32_t>(imm) << kImm16Shift));
   }
 
   inline void SetUnconditionalBranchRegBits(
       UnconditionalBranchRegOp op, Register rn) {
     SetInstructionBits(
         op |
         (static_cast<int32_t>(rn) << kRnShift));
   }
 
+  inline void SetImm12Bits(int32_t orig, int32_t imm12) {
+    ASSERT((imm12 & 0xfffff000) == 0);
+    SetInstructionBits((orig & ~kImm12Mask) | (imm12 << kImm12Shift));
+  }
+
   inline int NField() const { return Bit(22); }
   inline int SField() const { return Bit(kSShift); }
   inline int SFField() const { return Bit(kSFShift); }
   inline int SzField() const { return Bits(kSzShift, kSzBits); }
   inline Register RdField() const { return static_cast<Register>(
                                         Bits(kRdShift, kRdBits)); }
   inline Register RnField() const { return static_cast<Register>(
                                         Bits(kRnShift, kRnBits)); }
   inline Register RaField() const { return static_cast<Register>(
                                         Bits(kRaShift, kRaBits)); }
@@ skipping 179 matching lines @@
   static Instr* At(uword pc) { return reinterpret_cast<Instr*>(pc); }
 
  private:
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Instr);
 };
 
 }  // namespace dart
 
 #endif  // VM_CONSTANTS_ARM64_H_