Supports FrameLookup vm test on MIPS

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_
 
 namespace dart {
 
 enum Register {
@@ skipping 17 matching lines @@
   R16 = 16,
   R17 = 17,
   R18 = 18,
   R19 = 19,
   R20 = 20,
   R21 = 21,
   R22 = 22,
   R23 = 23,
   R24 = 24,
   R25 = 25,
   kLastFreeCpuRegister = 25,

[regis, 2013/04/10 20:53:00]

You can move this one up to = 21, now that you also use T8 as a tmp.

[zra, 2013/04/10 21:59:05]

Done.

   R26 = 26,
   R27 = 27,
   R28 = 28,
   R29 = 29,
   R30 = 30,
   R31 = 31,
   kNumberOfCpuRegisters = 32,
   kNoRegister = -1,
 
   // Register aliases.
@@ skipping 88 matching lines @@
 // Register aliases.
 const Register TMP1 = AT;  // Used as scratch register by assembler.
 const Register TMP2 = T9;  // Used as scratch register by assembler.
 const Register TMP = TMP1;  // Arch independent flow graph compiler needs a
                             // Register called TMP.
 const Register CTX = S6;  // Caches current context in generated code.
 const Register PP = S7;  // Caches object pool pointer in generated code.
 const Register SPREG = SP;  // Stack pointer register.
 const Register FPREG = FP;  // Frame pointer register.
 
+// The code that generates a comparison can be far away from the code that
+// generates the branch that uses the result of that comparison. In this case,
+// CMPRES is used for the result of the comparison.
+const Register CMPRES = T8;
 
 typedef uint32_t RegList;
 const RegList kAllCpuRegistersList = 0xFFFFFFFF;
 
 
 const RegList kAbiArgumentCpuRegs =
     (1 << A0) | (1 << A1) | (1 << A2) | (1 << A3);
 const RegList kAbiPreservedCpuRegs =
     (1 << S0) | (1 << S1) | (1 << S2) | (1 << S3) |
     (1 << S4) | (1 << S5) | (1 << S6) | (1 << S7);
 const int kAbiPreservedCpuRegCount = 8;
 
 
 // Dart stack frame layout.
 static const int kLastParamSlotIndex = 3;
 static const int kFirstLocalSlotIndex = -2;
 
 
-// Values for the condition field.  // UNIMPLEMENTED.
+// 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 {
-  kNoCondition = -1,
-  kMaxCondition = 16,
+  EQ,  // equal
+  NE,  // not equal

[regis, 2013/04/10 20:53:00]

I am not sure this will work once you get other conditions that do not map
directly to a branch.

 };
 
 
 // Constants used for the decoding or encoding of the individual fields of
 // instructions. Based on the "Table 4.25 CPU Instruction Format Fields".
 enum InstructionFields {
   kOpcodeShift = 26,
   kOpcodeBits = 6,
   kRsShift = 21,
   kRsBits = 5,
@@ skipping 222 matching lines @@
   static Instr* At(uword pc) { return reinterpret_cast<Instr*>(pc); }
 
  private:
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Instr);
 };
 
 }  // namespace dart
 
 #endif  // VM_CONSTANTS_MIPS_H_