Use off-heap data for type feedback in PolymorphicInstanceCallInstr

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 a948896cb9313ed3e2e02c9b9ec230955c6bd782..79382ef55d7671c2df50ee76c8d46c433d93634b 100644
--- a/runtime/vm/flow_graph_compiler_arm.cc
+++ b/runtime/vm/flow_graph_compiler_arm.cc
@@ -1213,16 +1213,14 @@ void FlowGraphCompiler::EmitInstanceCall(const StubEntry& stub_entry,
 
 
 void FlowGraphCompiler::EmitMegamorphicInstanceCall(
-    const ICData& ic_data,
+    const String& name,
+    const Array& arguments_descriptor,
     intptr_t argument_count,
     intptr_t deopt_id,
     TokenPosition token_pos,
     LocationSummary* locs,
     intptr_t try_index,
     intptr_t slow_path_argument_count) {
-  const String& name = String::Handle(zone(), ic_data.target_name());
-  const Array& arguments_descriptor =
-      Array::ZoneHandle(zone(), ic_data.arguments_descriptor());
   ASSERT(!arguments_descriptor.IsNull() && (arguments_descriptor.Length() > 0));
   const MegamorphicCache& cache = MegamorphicCache::ZoneHandle(
       zone(),
@@ -1480,7 +1478,8 @@ void FlowGraphCompiler::ClobberDeadTempRegisters(LocationSummary* locs) {
 #endif
 
 
-void FlowGraphCompiler::EmitTestAndCall(const ICData& ic_data,
+void FlowGraphCompiler::EmitTestAndCall(const PolymorphicTargets& targets,
+                                        const String& function_name,
                                         intptr_t argument_count,
                                         const Array& argument_names,
                                         Label* failed,
@@ -1491,57 +1490,68 @@ void FlowGraphCompiler::EmitTestAndCall(const ICData& ic_data,
                                         bool complete,
                                         intptr_t total_ic_calls) {
   ASSERT(is_optimizing());
+
   __ Comment("EmitTestAndCall");
   const Array& arguments_descriptor = Array::ZoneHandle(
       zone(), ArgumentsDescriptor::New(argument_count, argument_names));
-
   // Load receiver into R0.
   __ LoadFromOffset(kWord, R0, SP, (argument_count - 1) * kWordSize);
   __ LoadObject(R4, arguments_descriptor);
 
-  const bool kFirstCheckIsSmi = ic_data.GetReceiverClassIdAt(0) == kSmiCid;
-  const intptr_t num_checks = ic_data.NumberOfChecks();
-
-  ASSERT(!ic_data.IsNull() && (num_checks > 0));
+  const int kNoCase = -1;

[Vyacheslav Egorov (Google), 2017/04/10 10:59:27]

This code is duplicated in each architecture. Could you move it to some sort of
helper?

EmitTestAndCall on all architectures seems to follow the same pattern:

Prologue()
HandleSmiCase()
SwitchPrologue()
for (...) {
  HandleCase()
}
MegamorphicCall()

We should clean this up and unify these functions.

[erikcorry, 2017/04/19 15:06:39]

Done.

+  int smi_case = kNoCase;
+  int which_case_to_skip = kNoCase;
+
+  const int length = targets.length();
+  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;
+    }
+  }
 
-  Label after_smi_test;
-  if (kFirstCheckIsSmi) {
+  if (smi_case != kNoCase) {
+    Label after_smi_test;
     __ tst(R0, Operand(kSmiTagMask));
     // Jump if receiver is not Smi.
-    if (num_checks == 1) {
-      __ b(failed, NE);
-    } else {
-      __ b(&after_smi_test, NE);
-    }
+    __ b(non_smi_length == 0 ? failed : &after_smi_test, NE);
     // 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 =
-        Function::ZoneHandle(zone(), ic_data.GetTargetAt(0));
+    const Function& function = *targets[smi_case].target;
     GenerateStaticDartCall(deopt_id, token_index,
                            *StubCode::CallStaticFunction_entry(),
                            RawPcDescriptors::kOther, locs, function);
     __ Drop(argument_count);
-    if (num_checks > 1) {
+    if (non_smi_length > 0) {
       __ b(match_found);
     }
+    __ Bind(&after_smi_test);
   } else {
     // Receiver is Smi, but Smi is not a valid class therefore fail.
-    // (Smi class must be first in the list).
     if (!complete) {
       __ tst(R0, Operand(kSmiTagMask));
       __ b(failed, EQ);
     }
   }
-  __ Bind(&after_smi_test);
 
-  ASSERT(!ic_data.IsNull() && (num_checks > 0));
-  GrowableArray<CidRangeTarget> sorted(num_checks);
-  SortICDataByCount(ic_data, &sorted, /* drop_smi = */ true);
+  ASSERT(length > 0);
 
-  const intptr_t sorted_len = sorted.length();
-  // If sorted_len 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.
-  if (sorted_len == 0) return;
+  // 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.
+  if (non_smi_length == 0) return;
 
   // Value is not Smi,
   __ LoadClassId(R2, R0);
@@ -1549,21 +1559,25 @@ void FlowGraphCompiler::EmitTestAndCall(const ICData& ic_data,
   bool add_megamorphic_call = false;
   const int kMaxImmediateInInstruction = 256;
   int bias =
-      ComputeGoodBiasForCidComparison(sorted, kMaxImmediateInInstruction);
+      ComputeGoodBiasForCidComparison(targets, kMaxImmediateInInstruction);
   if (bias != 0) __ AddImmediate(R2, R2, -bias);
 
-  for (intptr_t i = 0; i < sorted_len; i++) {
-    const bool is_last_check = (i == (sorted_len - 1));
-    int cid_start = sorted[i].cid_start;
-    int cid_end = sorted[i].cid_end;
-    int count = sorted[i].count;
+  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 cid_start = targets[i].cid_start;
+    const int cid_end = targets[i].cid_end;
+    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.
+      // 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 HasSingleRecognizedCid.
       add_megamorphic_call = true;
       break;
     }
-    ASSERT(cid_start > kSmiCid || cid_end < kSmiCid);
     Label next_test;
     if (!complete || !is_last_check) {
       Label* next_label = is_last_check ? failed : &next_test;
@@ -1579,20 +1593,21 @@ void FlowGraphCompiler::EmitTestAndCall(const ICData& ic_data,
     }
     // 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 = *sorted[i].target;
+    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) {
+    if (!is_last_check || add_megamorphic_call) {
       __ b(match_found);
     }
     __ Bind(&next_test);
   }
   if (add_megamorphic_call) {
     int try_index = CatchClauseNode::kInvalidTryIndex;
-    EmitMegamorphicInstanceCall(ic_data, argument_count, deopt_id, token_index,
-                                locs, try_index, argument_count);
+    EmitMegamorphicInstanceCall(function_name, arguments_descriptor,
+                                argument_count, deopt_id, token_index, locs,
+                                try_index);
   }
 }