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

runtime/vm/flow_graph_compiler_x64.cc

Index: runtime/vm/flow_graph_compiler_x64.cc
diff --git a/runtime/vm/flow_graph_compiler_x64.cc b/runtime/vm/flow_graph_compiler_x64.cc
index 42b3677bc82c3adf48a372fd084373708321f716..8f5908d1ca4cecb4098b0fbf6f470af9d73be38a 100644
--- a/runtime/vm/flow_graph_compiler_x64.cc
+++ b/runtime/vm/flow_graph_compiler_x64.cc
@@ -29,6 +29,18 @@ DECLARE_FLAG(bool, enable_simd_inline);
 DECLARE_FLAG(bool, use_megamorphic_stub);
 
 
+void MegamorphicSlowPath::EmitNativeCode(FlowGraphCompiler* compiler) {
+  Assembler* assembler = compiler->assembler();
+#define __ assembler->
+  __ Bind(entry_label());
+  __ Comment("MegamorphicSlowPath");
+  compiler->EmitMegamorphicInstanceCall(ic_data_, argument_count_, deopt_id_,
+                                        token_pos_, locs_, try_index_);
+  __ jmp(exit_label());
+#undef __
+}
+
+
 FlowGraphCompiler::~FlowGraphCompiler() {
   // BlockInfos are zone-allocated, so their destructors are not called.
   // Verify the labels explicitly here.
@@ -175,8 +187,8 @@ void CompilerDeoptInfoWithStub::GenerateCode(FlowGraphCompiler* compiler,
                                              intptr_t stub_ix) {
   // Calls do not need stubs, they share a deoptimization trampoline.
   ASSERT(reason() != ICData::kDeoptAtCall);
-  Assembler* assem = compiler->assembler();
-#define __ assem->
+  Assembler* assembler = compiler->assembler();
+#define __ assembler->
   __ Comment("%s", Name());
   __ Bind(entry_label());
   if (FLAG_trap_on_deoptimization) {
@@ -187,7 +199,7 @@ void CompilerDeoptInfoWithStub::GenerateCode(FlowGraphCompiler* compiler,
 
   __ pushq(CODE_REG);
   __ Call(*StubCode::Deoptimize_entry());
-  set_pc_offset(assem->CodeSize());
+  set_pc_offset(assembler->CodeSize());
   __ int3();
 #undef __
 }
@@ -1279,7 +1291,8 @@ void FlowGraphCompiler::EmitMegamorphicInstanceCall(
     intptr_t argument_count,
     intptr_t deopt_id,
     intptr_t token_pos,
-    LocationSummary* locs) {
+    LocationSummary* locs,
+    intptr_t try_index) {
   const String& name = String::Handle(zone(), ic_data.target_name());
   const Array& arguments_descriptor =
       Array::ZoneHandle(zone(), ic_data.arguments_descriptor());
@@ -1297,13 +1310,26 @@ void FlowGraphCompiler::EmitMegamorphicInstanceCall(
   }
   __ call(RCX);
 
-  AddCurrentDescriptor(RawPcDescriptors::kOther,
-      Thread::kNoDeoptId, token_pos);
   RecordSafepoint(locs);
   const intptr_t deopt_id_after = Thread::ToDeoptAfter(deopt_id);
-  if (is_optimizing()) {
+  if (Compiler::always_optimize()) {
+    // Megamorphic calls may occur in slow path stubs.
+    // If valid use try_index argument.
+    if (try_index == CatchClauseNode::kInvalidTryIndex) {
+      try_index = CurrentTryIndex();
+    }
+    pc_descriptors_list()->AddDescriptor(RawPcDescriptors::kOther,
+                                         assembler()->CodeSize(),
+                                         Thread::kNoDeoptId,
+                                         token_pos,
+                                         try_index);
+  } else if (is_optimizing()) {
+    AddCurrentDescriptor(RawPcDescriptors::kOther,
+        Thread::kNoDeoptId, token_pos);
     AddDeoptIndexAtCall(deopt_id_after, token_pos);
   } else {
+    AddCurrentDescriptor(RawPcDescriptors::kOther,
+        Thread::kNoDeoptId, token_pos);
     // Add deoptimization continuation point after the call and before the
     // arguments are removed.
     AddCurrentDescriptor(RawPcDescriptors::kDeopt, deopt_id_after, token_pos);