Collect type profile for DevTools.

src/interpreter/bytecode-generator.cc

Index: src/interpreter/bytecode-generator.cc
diff --git a/src/interpreter/bytecode-generator.cc b/src/interpreter/bytecode-generator.cc
index d6ed4a0a67d40bf6d38ba2d21196c6cdaff4d5f0..bdd91b688f1c0573a3ceec9c79d341182fcf1072 100644
--- a/src/interpreter/bytecode-generator.cc
+++ b/src/interpreter/bytecode-generator.cc
@@ -921,6 +921,7 @@ void BytecodeGenerator::VisitVariableDeclaration(VariableDeclaration* decl) {
           ->LoadLiteral(variable->raw_name())
           .StoreAccumulatorInRegister(name)
           .CallRuntime(Runtime::kDeclareEvalVar, name);
+
       break;
     }
     case VariableLocation::MODULE:
@@ -2214,18 +2215,31 @@ void BytecodeGenerator::VisitAssignment(Assignment* expr) {
   LhsKind assign_type = Property::GetAssignType(property);
 
   // Evaluate LHS expression.
+  Register lhs_name = register_allocator()->NewRegister();
+
   switch (assign_type) {
     case VARIABLE:
+      if (FLAG_type_profile) {

[Yang, 2017/02/22 10:39:28]

The issue with this flag and snapshot is: if the function is part of the
snapshot, it may already have a feedback metadata created with this flag off.
When compiling the function here, we assume the feedback metadata to have been
created with this flag on.

Either we clear the feedback metadata when we serialize, along with the code, or
we figure out from the feedback metadata, if it exists, whether we have slots
reserved for type profile, instead of relying on the flag. I'll test whether
clearing the feedback metadata during serialization can be done.

We should not collect type profile for functions for which
SharedFunctionInfo::IsSubjectToDebugging returns false though, which every
function in the default startup snapshot does.

+        builder()
+            ->LoadLiteral(expr->target()->AsVariableProxy()->var()->raw_name())
+            .StoreAccumulatorInRegister(lhs_name);
+      }
       // Nothing to do to evaluate variable assignment LHS.
       break;
     case NAMED_PROPERTY: {
       object = VisitForRegisterValue(property->obj());
       name = property->key()->AsLiteral()->AsRawPropertyName();
+      if (FLAG_type_profile) {
+        builder()->LoadLiteral(name).StoreAccumulatorInRegister(lhs_name);
+      }
       break;
     }
     case KEYED_PROPERTY: {
       object = VisitForRegisterValue(property->obj());
       key = VisitForRegisterValue(property->key());
+      if (FLAG_type_profile) {
+        builder()->StoreAccumulatorInRegister(lhs_name);
+      }
       break;
     }
     case NAMED_SUPER_PROPERTY: {
@@ -2238,6 +2252,9 @@ void BytecodeGenerator::VisitAssignment(Assignment* expr) {
       builder()
           ->LoadLiteral(property->key()->AsLiteral()->AsRawPropertyName())
           .StoreAccumulatorInRegister(super_property_args[2]);
+      if (FLAG_type_profile) {
+        builder()->StoreAccumulatorInRegister(lhs_name);
+      }
       break;
     }
     case KEYED_SUPER_PROPERTY: {
@@ -2248,6 +2265,10 @@ void BytecodeGenerator::VisitAssignment(Assignment* expr) {
       VisitForRegisterValue(super_property->home_object(),
                             super_property_args[1]);
       VisitForRegisterValue(property->key(), super_property_args[2]);
+      if (FLAG_type_profile) {
+        builder()->StoreAccumulatorInRegister(lhs_name);
+      }
+
       break;
     }
   }
@@ -2336,6 +2357,17 @@ void BytecodeGenerator::VisitAssignment(Assignment* expr) {
       break;
     }
   }
+
+  // Value is in accumulator.
+  if (FLAG_type_profile) {
+    Register value = register_allocator()->NewRegister();
+    builder()->StoreAccumulatorInRegister(value);
+
+    FeedbackSlot collect_type_feedback_slot = expr->CollectTypeProfileSlot();
+
+    builder()->CollectTypeProfile(lhs_name, value,

[Yang, 2017/02/22 10:39:28]

We would at some point need a mapping from feedback slot to source position and
name, so that when we harvest the data collected in the feedback slots, we can
tell where to attribute it to.

In that case, all we need as arguments here are the value, and the vector slot
pair. We can then use the mapping to get the name and source position. That's a
bit less intrusive than getting names.

+                                  feedback_index(collect_type_feedback_slot));
+  }
 }
 
 void BytecodeGenerator::VisitYield(Yield* expr) {