DBC: Fleshing out the polymorphic instance call instruction

runtime/vm/simulator_dbc.cc

 // 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.
 
 #include <setjmp.h>  // NOLINT
 #include <stdlib.h>
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_DBC)
 
@@ skipping 1510 matching lines @@
       SimulatorHelpers::IncrementUsageCounter(FrameFunction(FP));
       InstanceCall2(thread, icdata, call_base, call_top,
                     &argdesc, &pp, &pc, &FP, &SP,
                     true /* optimized */);
     }
 
     DISPATCH();
   }
 
   {
+    BYTECODE(PushPolymorphicInstanceCall, A_D);
+    const uint8_t argc = rA;
+    const intptr_t cids_length = rD;
+    RawObject** args = SP - argc + 1;
+    const intptr_t receiver_cid = SimulatorHelpers::GetClassId(args[0]);
+    for (intptr_t i = 0; i < 2*cids_length; i+=2) {
+      const intptr_t icdata_cid = Bytecode::DecodeD(*(pc + i));
+      if (receiver_cid == icdata_cid) {
+        RawFunction* target =
+            RAW_CAST(Function, LOAD_CONSTANT(Bytecode::DecodeD(*(pc + i + 1))));
+        *++SP = target;
+        pc++;
+        break;
+      }
+    }
+    pc += 2 * cids_length;
+    DISPATCH();
+  }
+
+  {
     BYTECODE(NativeBootstrapCall, 0);
     RawFunction* function = FrameFunction(FP);
     RawObject** incoming_args =
         (function->ptr()->num_optional_parameters_ == 0)
             ? FrameArguments(FP, function->ptr()->num_fixed_parameters_)
             : FP;
 
     SimulatorBootstrapNativeCall native_target =
         reinterpret_cast<SimulatorBootstrapNativeCall>(SP[-1]);
     intptr_t argc_tag = reinterpret_cast<intptr_t>(SP[-0]);
@@ skipping 1487 matching lines @@
   pc_ = pc;
   special_[kExceptionSpecialIndex] = raw_exception;
   special_[kStacktraceSpecialIndex] = raw_stacktrace;
   buf->Longjmp();
   UNREACHABLE();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_DBC