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

runtime/vm/flow_graph_compiler_arm.cc

Index: runtime/vm/flow_graph_compiler_arm.cc
diff --git a/runtime/vm/flow_graph_compiler_arm.cc b/runtime/vm/flow_graph_compiler_arm.cc
index a11916db9e64fb4dc09567874900d56c39d8a174..8bc755224ea5ba6092c24795fc6b6f97245f38a3 100644
--- a/runtime/vm/flow_graph_compiler_arm.cc
+++ b/runtime/vm/flow_graph_compiler_arm.cc
@@ -31,6 +31,18 @@ DECLARE_FLAG(bool, enable_simd_inline);
 DECLARE_FLAG(bool, use_megamorphic_stub);
 
 
+void MegamorphicSlowPath::EmitNativeCode(FlowGraphCompiler* compiler) {
+  Assembler* assem = compiler->assembler();

[Florian Schneider, 2015/12/14 16:07:03]

s/assem/assembler/

[srdjan, 2015/12/15 17:52:03]

Done here and below (old code).

+#define __ assem->
+  __ Bind(entry_label());
+  __ Comment("MegamorphicSlowPath");
+  compiler->EmitMegamorphicInstanceCall(ic_data_, argument_count_, deopt_id_,
+                                        token_pos_, locs_, try_index_);
+  __ b(exit_label());
+#undef __
+}
+
+
 FlowGraphCompiler::~FlowGraphCompiler() {
   // BlockInfos are zone-allocated, so their destructors are not called.
   // Verify the labels explicitly here.
@@ -1258,7 +1270,8 @@ 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());
@@ -1279,7 +1292,18 @@ void FlowGraphCompiler::EmitMegamorphicInstanceCall(
   AddCurrentDescriptor(RawPcDescriptors::kOther, Thread::kNoDeoptId, token_pos);

[Florian Schneider, 2015/12/14 16:07:03]

Move this into the else-branches below, so that we don't record two descriptors
of the same type if Compiler::always_optimize() is true.

[srdjan, 2015/12/15 17:52:03]

Done.

   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()) {
     AddDeoptIndexAtCall(deopt_id_after, token_pos);
   } else {
     // Add deoptimization continuation point after the call and before the