Polymorphic calls in precompilation invoke megamorphic calls when tests fail (instead of deoptimizi…

runtime/vm/flow_graph_compiler.h

Index: runtime/vm/flow_graph_compiler.h
diff --git a/runtime/vm/flow_graph_compiler.h b/runtime/vm/flow_graph_compiler.h
index 075e239a4b5e005026eb6f890b5a8e550864c06b..b6d4c4c13ae061d5167d0ce4aad177a25a398b51 100644
--- a/runtime/vm/flow_graph_compiler.h
+++ b/runtime/vm/flow_graph_compiler.h
@@ -214,6 +214,37 @@ class SlowPathCode : public ZoneAllocated {
 };
 
 
+class MegamorphicSlowPath : public SlowPathCode {
+ public:
+  MegamorphicSlowPath(const ICData& ic_data,
+                      intptr_t argument_count,
+                      intptr_t deopt_id,
+                      intptr_t token_pos,
+                      LocationSummary* locs,
+                      intptr_t try_index)
+    : SlowPathCode(),
+      ic_data_(ic_data),
+      argument_count_(argument_count),
+      deopt_id_(deopt_id),
+      token_pos_(token_pos),
+      locs_(locs),
+      try_index_(try_index) {}
+  virtual ~MegamorphicSlowPath() {}
+
+ private:
+  virtual void EmitNativeCode(FlowGraphCompiler* comp);
+
+  const ICData& ic_data_;
+  intptr_t argument_count_;
+  intptr_t deopt_id_;
+  intptr_t token_pos_;
+  LocationSummary* locs_;
+  const intptr_t try_index_;  // For try/catch ranges.
+
+  DISALLOW_COPY_AND_ASSIGN(MegamorphicSlowPath);
+};
+
+
 struct CidTarget {
   intptr_t cid;
   Function* target;
@@ -414,11 +445,14 @@ class FlowGraphCompiler : public ValueObject {
                                    intptr_t token_pos,
                                    LocationSummary* locs);
 
-  void EmitMegamorphicInstanceCall(const ICData& ic_data,
-                                   intptr_t argument_count,
-                                   intptr_t deopt_id,
-                                   intptr_t token_pos,
-                                   LocationSummary* locs);
+  // Pass a value for try-index where block is not available (e.g. slow path).
+  void EmitMegamorphicInstanceCall(
+      const ICData& ic_data,
+      intptr_t argument_count,
+      intptr_t deopt_id,
+      intptr_t token_pos,
+      LocationSummary* locs,
+      intptr_t try_index = CatchClauseNode::kInvalidTryIndex);
 
   void EmitSwitchableInstanceCall(const ICData& ic_data,
                                   intptr_t argument_count,