VM-codegen: Restrict widening class ranges in method dispatch

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index 9db5af0f6200ebc24587140cb70c0304e61607cc..68cf40125c2256810f757cb0aa8dc01ef8ffe21c 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -2978,9 +2978,13 @@ CallTargets* CallTargets::CreateAndExpand(Zone* zone, const ICData& ic_data) {
     const Function& target = *targets.TargetAt(idx)->target;
     if (MethodRecognizer::PolymorphicTarget(target)) continue;
     for (int i = targets[idx].cid_start - 1; i > lower_limit_cid; i--) {
-      if (FlowGraphCompiler::LookupMethodFor(i, name, args_desc, &fn) &&
+      bool class_is_abstract = false;
+      if (FlowGraphCompiler::LookupMethodFor(i, name, args_desc, &fn,
+                                             &class_is_abstract) &&
           fn.raw() == target.raw()) {
-        targets[idx].cid_start = i;
+        if (!class_is_abstract) {
+          targets[idx].cid_start = i;
+        }
       } else {
         break;
       }
@@ -2994,9 +2998,13 @@ CallTargets* CallTargets::CreateAndExpand(Zone* zone, const ICData& ic_data) {
     const Function& target = *targets.TargetAt(idx)->target;
     if (MethodRecognizer::PolymorphicTarget(target)) continue;
     for (int i = targets[idx].cid_end + 1; i < upper_limit_cid; i++) {
-      if (FlowGraphCompiler::LookupMethodFor(i, name, args_desc, &fn) &&
+      bool class_is_abstract = false;
+      if (FlowGraphCompiler::LookupMethodFor(i, name, args_desc, &fn,
+                                             &class_is_abstract) &&
           fn.raw() == target.raw()) {
-        targets[idx].cid_end = i;
+        if (!class_is_abstract) {
+          targets[idx].cid_end = i;
+        }
       } else {
         break;
       }