Cleanup: Make CheckClassId instruction more general so it

runtime/vm/constants_dbc.h

Index: runtime/vm/constants_dbc.h
diff --git a/runtime/vm/constants_dbc.h b/runtime/vm/constants_dbc.h
index becbe0335dd4b738b31b12e90f5268c5eb7337a3..d1a953b4c5ae1fe84c2f8f62a03936ef12338d0d 100644
--- a/runtime/vm/constants_dbc.h
+++ b/runtime/vm/constants_dbc.h
@@ -590,6 +590,11 @@ namespace dart {
 //    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
@@ -841,6 +846,7 @@ namespace dart {
   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) \