DBC: Fleshing out the polymorphic instance call instruction

runtime/vm/simulator_dbc.cc

Index: runtime/vm/simulator_dbc.cc
diff --git a/runtime/vm/simulator_dbc.cc b/runtime/vm/simulator_dbc.cc
index 226222ccf711ccd391e3b29fa51acbfabb1d262d..c26cb7500b95f80df22c7961b2314a27a2ceb193 100644
--- a/runtime/vm/simulator_dbc.cc
+++ b/runtime/vm/simulator_dbc.cc
@@ -1528,6 +1528,26 @@ RawObject* Simulator::Call(const Code& code,
   }
 
   {
+    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 =