Collect type profile for DevTools.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-generator.h"
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/scopes.h"
 #include "src/builtins/builtins-constructor.h"
 #include "src/code-stubs.h"
@@ skipping 2196 matching lines @@
   DCHECK(expr->target()->IsValidReferenceExpressionOrThis());
   Register object, key;
   RegisterList super_property_args;
   const AstRawString* name;
 
   // Left-hand side can only be a property, a global or a variable slot.
   Property* property = expr->target()->AsProperty();
   LhsKind assign_type = Property::GetAssignType(property);
 
   // Evaluate LHS expression.
+  Register lhs_name;

[Yang, 2017/03/09 10:28:27]

Do we have a plan to use a better way to identify variables than names? Variable
names could be ambiguous due to shadowing, and we would need a mapping from
feedback slot to name and source position that we can use when we harvest all
type profile information at once. I wonder whether we can store this mapping in
the feedback metadata.

Maybe we only need the mapping from slot to bytecode offset of the declaration,
and from there we could extract the variable name and the source position from
the bytecode array and source position table.

[Franzi, 2017/03/10 12:14:29]

I'm only passing the name so that I can understand the debug output. My plan is
to not use the name at all. 

+  if (expr->HasCollectTypeProfileSlot()) {
+    lhs_name = register_allocator()->NewRegister();
+  }
+
   switch (assign_type) {
     case VARIABLE:
+      if (expr->HasCollectTypeProfileSlot()) {
+        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 (expr->HasCollectTypeProfileSlot()) {
+        builder()->LoadLiteral(name).StoreAccumulatorInRegister(lhs_name);
+      }
       break;
     }
     case KEYED_PROPERTY: {
       object = VisitForRegisterValue(property->obj());
       key = VisitForRegisterValue(property->key());
+      if (expr->HasCollectTypeProfileSlot()) {
+        builder()->StoreAccumulatorInRegister(lhs_name);
+      }
       break;
     }
     case NAMED_SUPER_PROPERTY: {
       super_property_args = register_allocator()->NewRegisterList(4);
       SuperPropertyReference* super_property =
           property->obj()->AsSuperPropertyReference();
       VisitForRegisterValue(super_property->this_var(), super_property_args[0]);
       VisitForRegisterValue(super_property->home_object(),
                             super_property_args[1]);
       builder()
           ->LoadLiteral(property->key()->AsLiteral()->AsRawPropertyName())
           .StoreAccumulatorInRegister(super_property_args[2]);
+      if (expr->HasCollectTypeProfileSlot()) {
+        builder()->StoreAccumulatorInRegister(lhs_name);
+      }
       break;
     }
     case KEYED_SUPER_PROPERTY: {
       super_property_args = register_allocator()->NewRegisterList(4);
       SuperPropertyReference* super_property =
           property->obj()->AsSuperPropertyReference();
       VisitForRegisterValue(super_property->this_var(), super_property_args[0]);
       VisitForRegisterValue(super_property->home_object(),
                             super_property_args[1]);
       VisitForRegisterValue(property->key(), super_property_args[2]);
+      if (expr->HasCollectTypeProfileSlot()) {
+        builder()->StoreAccumulatorInRegister(lhs_name);
+      }
+
       break;
     }
   }
 
   // Evaluate the value and potentially handle compound assignments by loading
   // the left-hand side value and performing a binary operation.
   if (expr->is_compound()) {
     Register old_value = register_allocator()->NewRegister();
     switch (assign_type) {
       case VARIABLE: {
@@ skipping 68 matching lines @@
           .CallRuntime(StoreToSuperRuntimeId(), super_property_args);
       break;
     }
     case KEYED_SUPER_PROPERTY: {
       builder()
           ->StoreAccumulatorInRegister(super_property_args[3])
           .CallRuntime(StoreKeyedToSuperRuntimeId(), super_property_args);
       break;
     }
   }
+
+  // Value is in accumulator.
+  if (expr->HasCollectTypeProfileSlot()) {
+    FeedbackSlot collect_type_feedback_slot = expr->CollectTypeProfileSlot();
+
+    builder()->CollectTypeProfile(lhs_name,
+                                  feedback_index(collect_type_feedback_slot));
+  }
 }
 
 void BytecodeGenerator::VisitYield(Yield* expr) {
   builder()->SetExpressionPosition(expr);
   Register value = VisitForRegisterValue(expr->expression());
 
   Register generator = VisitForRegisterValue(expr->generator_object());
 
   // Save context, registers, and state. Then return.
   builder()
@@ skipping 1122 matching lines @@
 }
 
 Runtime::FunctionId BytecodeGenerator::StoreKeyedToSuperRuntimeId() {
   return is_strict(language_mode()) ? Runtime::kStoreKeyedToSuper_Strict
                                     : Runtime::kStoreKeyedToSuper_Sloppy;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8