Use off-heap data for type feedback in PolymorphicInstanceCallInstr

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
diff --git a/runtime/vm/flow_graph_compiler.cc b/runtime/vm/flow_graph_compiler.cc
index 866cab4de2588fd832ce9d9a245ef424aee606ec..fd9f649f5f31b6b0d8fae349de4a52b2e304b02a 100644
--- a/runtime/vm/flow_graph_compiler.cc
+++ b/runtime/vm/flow_graph_compiler.cc
@@ -23,6 +23,7 @@
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/raw_object.h"
+#include "vm/resolver.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
@@ -1169,8 +1170,12 @@ void FlowGraphCompiler::GenerateInstanceCall(intptr_t deopt_id,
   }
 
   if (is_optimizing()) {
-    EmitMegamorphicInstanceCall(ic_data_in, argument_count, deopt_id, token_pos,
-                                locs, CatchClauseNode::kInvalidTryIndex);
+    String& name = String::Handle(ic_data_in.target_name());
+    Array& arguments_descriptor =
+        Array::Handle(ic_data_in.arguments_descriptor());
+    EmitMegamorphicInstanceCall(name, arguments_descriptor, argument_count,
+                                deopt_id, token_pos, locs,
+                                CatchClauseNode::kInvalidTryIndex);
     return;
   }
 
@@ -1787,38 +1792,26 @@ void FlowGraphCompiler::EndCodeSourceRange(TokenPosition token_pos) {
 }
 
 
-const ICData& FlowGraphCompiler::TrySpecializeICDataByReceiverCid(
-    const ICData& ic_data,
-    intptr_t cid) {
+const CallTargets* FlowGraphCompiler::ResolveCallTargetsForReceiverCid(
+    intptr_t cid,
+    const String& selector,
+    const Array& args_desc_array) {
   Zone* zone = Thread::Current()->zone();
-  if (ic_data.NumArgsTested() != 1) return ic_data;
 
-  if ((ic_data.NumberOfUsedChecks() == 1) && ic_data.HasReceiverClassId(cid)) {
-    return ic_data;  // Nothing to do
-  }
+  ArgumentsDescriptor args_desc(args_desc_array);
 
-  intptr_t count = 1;
-  const Function& function =
-      Function::Handle(zone, ic_data.GetTargetForReceiverClassId(cid, &count));
-  // TODO(fschneider): Try looking up the function on the class if it is
-  // not found in the ICData.
-  if (!function.IsNull()) {
-    const ICData& new_ic_data = ICData::ZoneHandle(
-        zone, ICData::New(Function::Handle(zone, ic_data.Owner()),
-                          String::Handle(zone, ic_data.target_name()),
-                          Object::empty_array(),  // Dummy argument descriptor.
-                          ic_data.deopt_id(), ic_data.NumArgsTested(), false));
-    new_ic_data.SetDeoptReasons(ic_data.DeoptReasons());
-    new_ic_data.AddReceiverCheck(cid, function, count);
-    return new_ic_data;
-  }
+  Function& fn = Function::ZoneHandle(zone);
+  if (!LookupMethodFor(cid, selector, args_desc, &fn)) return NULL;
 
-  return ic_data;
+  CallTargets* targets = new (zone) CallTargets();
+  targets->Add(CidRangeTarget(cid, cid, &fn, /* count = */ 1));
+
+  return targets;
 }
 
 
 intptr_t FlowGraphCompiler::ComputeGoodBiasForCidComparison(
-    const GrowableArray<CidRangeTarget>& sorted,
+    const CallTargets& sorted,
     intptr_t max_immediate) {
   // Sometimes a bias can be useful so we can emit more compact compare
   // instructions.
@@ -1849,22 +1842,52 @@ intptr_t FlowGraphCompiler::ComputeGoodBiasForCidComparison(
 }
 
 
+bool FlowGraphCompiler::LookupMethodFor(int class_id,
+                                        const String& name,
+                                        const ArgumentsDescriptor& args_desc,
+                                        Function* fn_return) {
+  Thread* thread = Thread::Current();
+  Isolate* isolate = thread->isolate();
+  Zone* zone = thread->zone();
+  if (class_id < 0) return false;
+  if (class_id >= isolate->class_table()->NumCids()) return false;
+
+  RawClass* raw_class = isolate->class_table()->At(class_id);
+  if (raw_class == NULL) return false;
+  Class& cls = Class::Handle(zone, raw_class);
+  if (cls.IsNull()) return false;
+  if (!cls.is_finalized()) return false;
+  if (Array::Handle(cls.functions()).IsNull()) return false;
+
+  const bool allow_add = false;
+  Function& target_function =
+      Function::Handle(zone, Resolver::ResolveDynamicForReceiverClass(
+                                 cls, name, args_desc, allow_add));
+  if (target_function.IsNull()) return false;
+  *fn_return ^= target_function.raw();
+  return true;
+}
+
+
 #if !defined(TARGET_ARCH_DBC)
 // DBC emits calls very differently from other architectures due to its
 // interpreted nature.
-void FlowGraphCompiler::EmitPolymorphicInstanceCall(const ICData& ic_data,
-                                                    intptr_t argument_count,
-                                                    const Array& argument_names,
-                                                    intptr_t deopt_id,
-                                                    TokenPosition token_pos,
-                                                    LocationSummary* locs,
-                                                    bool complete,
-                                                    intptr_t total_ic_calls) {
+void FlowGraphCompiler::EmitPolymorphicInstanceCall(
+    const CallTargets& targets,
+    const InstanceCallInstr& original_call,
+    intptr_t argument_count,
+    const Array& argument_names,
+    intptr_t deopt_id,
+    TokenPosition token_pos,
+    LocationSummary* locs,
+    bool complete,
+    intptr_t total_ic_calls) {
   if (FLAG_polymorphic_with_deopt) {
     Label* deopt =
         AddDeoptStub(deopt_id, ICData::kDeoptPolymorphicInstanceCallTestFail);
     Label ok;
-    EmitTestAndCall(ic_data, argument_count, argument_names,
+    EmitTestAndCall(targets, original_call.function_name(), argument_count,
+                    argument_names,
                     deopt,  // No cid match.
                     &ok,    // Found cid.
                     deopt_id, token_pos, locs, complete, total_ic_calls);
@@ -1872,17 +1895,144 @@ void FlowGraphCompiler::EmitPolymorphicInstanceCall(const ICData& ic_data,
   } else {
     if (complete) {
       Label ok;
-      EmitTestAndCall(ic_data, argument_count, argument_names,
+      EmitTestAndCall(targets, original_call.function_name(), argument_count,
+                      argument_names,
                       NULL,  // No cid match.
                       &ok,   // Found cid.
                       deopt_id, token_pos, locs, true, total_ic_calls);
       assembler()->Bind(&ok);
     } else {
-      EmitSwitchableInstanceCall(ic_data, argument_count, deopt_id, token_pos,
-                                 locs);
+      const ICData& unary_checks = ICData::ZoneHandle(
+          zone(), original_call.ic_data()->AsUnaryClassChecks());
+      EmitSwitchableInstanceCall(unary_checks, argument_count, deopt_id,
+                                 token_pos, locs);
+    }
+  }
+}
+
+
+#define __ assembler()->
+void FlowGraphCompiler::EmitTestAndCall(const CallTargets& targets,
+                                        const String& function_name,
+                                        intptr_t argument_count,
+                                        const Array& argument_names,
+                                        Label* failed,
+                                        Label* match_found,
+                                        intptr_t deopt_id,
+                                        TokenPosition token_index,
+                                        LocationSummary* locs,
+                                        bool complete,
+                                        intptr_t total_ic_calls) {
+  ASSERT(is_optimizing());
+
+  const Array& arguments_descriptor = Array::ZoneHandle(
+      zone(), ArgumentsDescriptor::New(argument_count, argument_names));
+
+  EmitTestAndCallLoadReceiver(argument_count, arguments_descriptor);
+
+  static const int kNoCase = -1;
+  int smi_case = kNoCase;
+  int which_case_to_skip = kNoCase;
+
+  const int length = targets.length();
+  ASSERT(length > 0);
+  int non_smi_length = length;
+
+  // Find out if one of the classes in one of the cases is the Smi class. We
+  // will be handling that specially.
+  for (int i = 0; i < length; i++) {
+    const intptr_t start = targets[i].cid_start;
+    if (start > kSmiCid) continue;
+    const intptr_t end = targets[i].cid_end;
+    if (end >= kSmiCid) {
+      smi_case = i;
+      if (start == kSmiCid && end == kSmiCid) {
+        // If this case has only the Smi class then we won't need to emit it at
+        // all later.
+        which_case_to_skip = i;
+        non_smi_length--;
+      }
+      break;
     }
   }
+
+  if (smi_case != kNoCase) {
+    Label after_smi_test;
+    // Jump if receiver is not Smi.
+    EmitTestAndCallSmiBranch(non_smi_length == 0 ? failed : &after_smi_test,
+                             false);
+
+    // Do not use the code from the function, but let the code be patched so
+    // that we can record the outgoing edges to other code.
+    const Function& function = *targets[smi_case].target;
+    GenerateStaticDartCall(deopt_id, token_index,
+                           *StubCode::CallStaticFunction_entry(),
+                           RawPcDescriptors::kOther, locs, function);
+    __ Drop(argument_count);
+    if (match_found != NULL) {
+      EmitTestAndCallGotoMatchFound(match_found);
+    }
+    __ Bind(&after_smi_test);
+  } else {
+    if (!complete) {
+      // Smi is not a valid class so jump to fail if it's a Smi.
+      EmitTestAndCallSmiBranch(failed, true);

[Vyacheslav Egorov (Google), 2017/04/20 16:45:33]

please add a comment what true/false means in this context.

[erikcorry, 2017/04/21 13:04:43]

Done.

+    }
+  }
+
+  if (non_smi_length == 0) {
+    // If non_smi_length is 0 then only a Smi check was needed; the Smi check
+    // above will fail if there was only one check and receiver is not Smi.
+    return;
+  }
+
+  bool add_megamorphic_call = false;
+  const int kMaxImmediateInInstruction = 256;

[Vyacheslav Egorov (Google), 2017/04/20 16:45:33]

Maybe add a note that this works on all architectures?

[erikcorry, 2017/04/21 13:04:43]

This wasn't a very noticable win (microscopic code density improvement) so I got
rid of it instead.

+  int bias =
+      ComputeGoodBiasForCidComparison(targets, kMaxImmediateInInstruction);
+
+  // Value is not Smi.
+  EmitTestAndCallLoadCid(bias);
+
+  int last_check = which_case_to_skip == length - 1 ? length - 2 : length - 1;
+
+  for (intptr_t i = 0; i < length; i++) {
+    if (i == which_case_to_skip) continue;
+    const bool is_last_check = (i == last_check);
+    const int count = targets[i].count;
+    if (!is_last_check && !complete && count < (total_ic_calls >> 5)) {
+      // This case is hit too rarely to be worth writing class-id checks inline
+      // for.  Note that we can't do this for calls with only one target because
+      // the type propagator may have made use of that and expects a deopt if
+      // a new class is seen at this calls site.  See IsMonomorphic.
+      add_megamorphic_call = true;
+      break;
+    }
+    Label next_test;
+    if (!complete || !is_last_check) {
+      bias = EmitTestAndCallCheckCid(is_last_check ? failed : &next_test,
+                                     targets[i], bias);
+    }
+    // Do not use the code from the function, but let the code be patched so
+    // that we can record the outgoing edges to other code.
+    const Function& function = *targets[i].target;
+    GenerateStaticDartCall(deopt_id, token_index,
+                           *StubCode::CallStaticFunction_entry(),
+                           RawPcDescriptors::kOther, locs, function);
+    __ Drop(argument_count);
+    if (!is_last_check || add_megamorphic_call) {
+      EmitTestAndCallGotoMatchFound(match_found);
+    }
+    __ Bind(&next_test);
+  }
+  if (add_megamorphic_call) {
+    int try_index = CatchClauseNode::kInvalidTryIndex;
+    EmitMegamorphicInstanceCall(function_name, arguments_descriptor,
+                                argument_count, deopt_id, token_index, locs,
+                                try_index);
+  }
 }
+#undef __
 #endif
 
 #if defined(DEBUG) && !defined(TARGET_ARCH_DBC)