Cleanup: Make CheckClassId instruction more general so it

runtime/vm/constants_dbc.h

 // Copyright (c) 2016, 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 RUNTIME_VM_CONSTANTS_DBC_H_
 #define RUNTIME_VM_CONSTANTS_DBC_H_
 
 #include "platform/globals.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 572 matching lines @@
 //
 //  - CheckEitherNonSmi rA, rD
 //
 //    If either FP[rA] or FP[rD] is not a Smi, then skip the next instruction.
 //
 //  - CheckClassId rA, D
 //
 //    If the class id in FP[rA] matches the class id D, then skip the
 //    following instruction.
 //
+//  - CheckClassIdRange rA, B, C
+//
+//    If the class id in FP[rA] is between the class ids B and C, then skip the
+//    following instruction.
+//
 //  - CheckBitTest rA, D
 //
 //    Skips the next 3 instructions if the object at FP[rA] is a valid class for
 //    a dense switch with low cid encoded in the following Nop instruction, and
 //    the cid mask encoded in the Nop instruction after that, or if D == 1 and
 //    FP[rA] is a Smi. Skips 2 instructions otherwise.
 //
 //  - CheckCids rA, rB, rC
 //
 //    Skips rC + 1 instructions if the object at FP[rA] is a Smi and
@@ skipping 231 matching lines @@
   V(InstantiateTypeArgumentsTOS,         A_D, num, lit, ___) \
   V(InstanceOf,                            0, ___, ___, ___) \
   V(BadTypeError,                          0, ___, ___, ___) \
   V(AssertAssignable,                    A_D, num, lit, ___) \
   V(AssertBoolean,                         A, num, ___, ___) \
   V(TestSmi,                             A_D, reg, reg, ___) \
   V(TestCids,                            A_D, reg, num, ___) \
   V(CheckSmi,                              A, reg, ___, ___) \
   V(CheckEitherNonSmi,                   A_D, reg, reg, ___) \
   V(CheckClassId,                        A_D, reg, num, ___) \
+  V(CheckClassIdRange,                 A_B_C, reg, num, num) \

[kustermann, 2017/05/18 09:59:45]

The class range [start, end] limits are constrained to be in [0, 255] due to the
4-byte bytecode encoding. Is it anywhere enforced that we will never use the
cid-range chedck instructions if we have more than 255 classes?

[erikcorry, 2017/05/18 14:25:30]

Changed to a 16 bit representation with the 2nd argument in a following Nop
instruction.

   V(CheckBitTest,                        A_D, reg, num, ___) \
   V(CheckCids,                         A_B_C, reg, num, num) \
   V(CheckCidsByRange,                  A_B_C, reg, num, num) \
   V(CheckStack,                            0, ___, ___, ___) \
   V(CheckStackAlwaysExit,                  0, ___, ___, ___) \
   V(DebugStep,                             0, ___, ___, ___) \
   V(DebugBreak,                            A, num, ___, ___) \
   V(Deopt,                               A_D, num, num, ___) \
   V(DeoptRewind,                           0, ___, ___, ___)
 
@@ skipping 133 matching lines @@
 
 // After a comparison, the condition NEXT_IS_TRUE means the following
 // instruction is executed if the comparison is true and skipped over overwise.
 // Condition NEXT_IS_FALSE means the following instruction is executed if the
 // comparison is false and skipped over otherwise.
 enum Condition { NEXT_IS_TRUE, NEXT_IS_FALSE };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_CONSTANTS_DBC_H_