Cleanup deoptimization code to make it architecture independent (in progress).

runtime/vm/constants_mips.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_MIPS_H_
 #define VM_CONSTANTS_MIPS_H_
 
 #include "platform/assert.h"
 
 namespace dart {
@@ skipping 183 matching lines @@
     kDartAvailableCpuRegs & ~kAbiPreservedCpuRegs;
 const int kDartVolatileCpuRegCount = 14;
 const Register kDartFirstVolatileCpuReg = R2;
 const Register kDartLastVolatileCpuReg = R15;
 
 // FPU registers 0 - 19 are not preserved across calls.
 const FRegister kDartFirstVolatileFpuReg = F0;
 const FRegister kDartLastVolatileFpuReg = F19;
 const int kDartVolatileFpuRegCount = 20;
 
+
+// TODO(regis): Move these constants to stack_frame_mips.h.
 // Dart stack frame layout.
-static const int kLastParamSlotIndex = 3;
-static const int kFirstLocalSlotIndex = -2;
+static const int kLastParamSlotIndex = 3;  // From fp.
+static const int kFirstLocalSlotIndex = -2;  // From fp.
+static const int kPcSlotIndexFromSp = -2;
+
+/* MIPS Dart Frame Layout
+
+               |                   | <- TOS
+Callee frame   | ...               |
+               | current RA        |    (PC of current frame)
+               | PC Marker         |    (callee's frame code entry)
+               +-------------------+
+Current frame  | ...               | <- SP of current frame
+               | first local       |
+               | caller's PP       |
+               | caller's FP       | <- FP of current frame
+               | caller's RA       |    (PC of caller frame)
+               | PC Marker         |    (current frame's code entry)
+               +-------------------+
+Caller frame   | last parameter    |
+               |  ...              |
+*/
 
 
 // Values for the condition field.
 // There is no condition field on MIPS, but Conditions are used and passed
 // around by the intermediate language, so we need them here, too.
 enum Condition {
   EQ,  // equal
   NE,  // not equal
   GT,  // greater than
   GE,  // greater equal
@@ skipping 328 matching lines @@
 #endif  // defined(DEBUG)
 
  private:
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Instr);
 };
 
 }  // namespace dart
 
 #endif  // VM_CONSTANTS_MIPS_H_