Preparsing inner funcs: be less pessimistic about maybe_assigned.

src/parsing/preparser.h

Index: src/parsing/preparser.h
diff --git a/src/parsing/preparser.h b/src/parsing/preparser.h
index 58a0137e2664545ae6b45169efbd3c67b06294cf..28074a65af64993a1cb65612458e697f783bc0ce 100644
--- a/src/parsing/preparser.h
+++ b/src/parsing/preparser.h
@@ -5,6 +5,7 @@
 #ifndef V8_PARSING_PREPARSER_H
 #define V8_PARSING_PREPARSER_H
 
+#include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/parsing/parser-base.h"
 #include "src/parsing/preparse-data.h"
@@ -126,25 +127,26 @@ class PreParserIdentifier {
 class PreParserExpression {
  public:
   PreParserExpression()
-      : code_(TypeField::encode(kEmpty)), identifiers_(nullptr) {}
+      : code_(TypeField::encode(kEmpty)), variables_(nullptr) {}
 
   static PreParserExpression Empty() { return PreParserExpression(); }
 
   static PreParserExpression Default(
-      ZoneList<const AstRawString*>* identifiers = nullptr) {
-    return PreParserExpression(TypeField::encode(kExpression), identifiers);
+      ZoneList<VariableProxy*>* variables = nullptr) {
+    return PreParserExpression(TypeField::encode(kExpression), variables);
   }
 
   static PreParserExpression Spread(PreParserExpression expression) {
     return PreParserExpression(TypeField::encode(kSpreadExpression),
-                               expression.identifiers_);
+                               expression.variables_);
   }
 
   static PreParserExpression FromIdentifier(PreParserIdentifier id,
+                                            VariableProxy* variable,
                                             Zone* zone) {
     PreParserExpression expression(TypeField::encode(kIdentifierExpression) |
                                    IdentifierTypeField::encode(id.type_));
-    expression.AddIdentifier(id.string_, zone);
+    expression.AddVariable(variable, zone);
     return expression;
   }
 
@@ -155,22 +157,22 @@ class PreParserExpression {
   }
 
   static PreParserExpression Assignment(
-      ZoneList<const AstRawString*>* identifiers = nullptr) {
+      ZoneList<VariableProxy*>* variables = nullptr) {

[neis, 2016/12/12 13:01:36]

Can we remove the default value here and below? I think it's not used.

[marja, 2016/12/12 13:36:46]

Done.

     return PreParserExpression(TypeField::encode(kExpression) |
                                    ExpressionTypeField::encode(kAssignment),
-                               identifiers);
+                               variables);
   }
 
   static PreParserExpression ObjectLiteral(
-      ZoneList<const AstRawString*>* identifiers = nullptr) {
+      ZoneList<VariableProxy*>* variables = nullptr) {
     return PreParserExpression(TypeField::encode(kObjectLiteralExpression),
-                               identifiers);
+                               variables);
   }
 
   static PreParserExpression ArrayLiteral(
-      ZoneList<const AstRawString*>* identifiers = nullptr) {
+      ZoneList<VariableProxy*>* variables = nullptr) {
     return PreParserExpression(TypeField::encode(kArrayLiteralExpression),
-                               identifiers);
+                               variables);
   }
 
   static PreParserExpression StringLiteral() {
@@ -347,19 +349,18 @@ class PreParserExpression {
     kAssignment
   };
 
-  explicit PreParserExpression(
-      uint32_t expression_code,
-      ZoneList<const AstRawString*>* identifiers = nullptr)
-      : code_(expression_code), identifiers_(identifiers) {}
+  explicit PreParserExpression(uint32_t expression_code,
+                               ZoneList<VariableProxy*>* variables = nullptr)
+      : code_(expression_code), variables_(variables) {}
 
-  void AddIdentifier(const AstRawString* identifier, Zone* zone) {
-    if (identifier == nullptr) {
+  void AddVariable(VariableProxy* variable, Zone* zone) {
+    if (variable == nullptr) {
       return;
     }
-    if (identifiers_ == nullptr) {
-      identifiers_ = new (zone) ZoneList<const AstRawString*>(1, zone);
+    if (variables_ == nullptr) {
+      variables_ = new (zone) ZoneList<VariableProxy*>(1, zone);
     }
-    identifiers_->Add(identifier, zone);
+    variables_->Add(variable, zone);
   }
 
   // The first three bits are for the Type.
@@ -382,9 +383,9 @@ class PreParserExpression {
   typedef BitField<bool, TypeField::kNext, 1> HasCoverInitializedNameField;
 
   uint32_t code_;
-  // If the PreParser is used in the identifier tracking mode,
-  // PreParserExpression accumulates identifiers in that expression.
-  ZoneList<const AstRawString*>* identifiers_;
+  // If the PreParser is used in the variable tracking mode, PreParserExpression
+  // accumulates variables in that expression.
+  ZoneList<VariableProxy*>* variables_;
 
   friend class PreParser;
   friend class PreParserFactory;
@@ -394,13 +395,13 @@ class PreParserExpression {
 
 
 // The pre-parser doesn't need to build lists of expressions, identifiers, or
-// the like. If the PreParser is used in identifier tracking mode, it needs to
-// build lists of identifiers though.
+// the like. If the PreParser is used in variable tracking mode, it needs to
+// build lists of variables though.
 template <typename T>
 class PreParserList {
  public:
   // These functions make list->Add(some_expression) work (and do nothing).
-  PreParserList() : length_(0), identifiers_(nullptr) {}
+  PreParserList() : length_(0), variables_(nullptr) {}
   PreParserList* operator->() { return this; }
   void Add(T, Zone* zone);
   int length() const { return length_; }
@@ -408,9 +409,9 @@ class PreParserList {
   bool IsNull() const { return length_ == -1; }
 
  private:
-  explicit PreParserList(int n) : length_(n), identifiers_(nullptr) {}
+  explicit PreParserList(int n) : length_(n), variables_(nullptr) {}
   int length_;
-  ZoneList<const AstRawString*>* identifiers_;
+  ZoneList<VariableProxy*>* variables_;
 
   friend class PreParser;
   friend class PreParserFactory;
@@ -419,14 +420,14 @@ class PreParserList {
 template <>
 inline void PreParserList<PreParserExpression>::Add(
     PreParserExpression expression, Zone* zone) {
-  if (expression.identifiers_ != nullptr) {
+  if (expression.variables_ != nullptr) {
     DCHECK(FLAG_lazy_inner_functions);
     DCHECK(zone != nullptr);
-    if (identifiers_ == nullptr) {
-      identifiers_ = new (zone) ZoneList<const AstRawString*>(1, zone);
+    if (variables_ == nullptr) {
+      variables_ = new (zone) ZoneList<VariableProxy*>(1, zone);
     }
-    for (auto identifier : (*expression.identifiers_)) {
-      identifiers_->Add(identifier, zone);
+    for (auto identifier : (*expression.variables_)) {
+      variables_->Add(identifier, zone);
     }
   }
   ++length_;
@@ -525,7 +526,8 @@ class PreParserStatement {
 class PreParserFactory {
  public:
   explicit PreParserFactory(AstValueFactory* ast_value_factory)
-      : zone_(ast_value_factory->zone()) {}
+      : ast_value_factory_(ast_value_factory),
+        zone_(ast_value_factory->zone()) {}
 
   void set_zone(Zone* zone) { zone_ = zone; }
 
@@ -534,7 +536,14 @@ class PreParserFactory {
     // This is needed for object literal property names. Property names are
     // normalized to string literals during object literal parsing.
     PreParserExpression expression = PreParserExpression::Default();
-    expression.AddIdentifier(identifier.string_, zone_);
+    if (identifier.string_ != nullptr) {
+      DCHECK(FLAG_lazy_inner_functions);
+      AstNodeFactory factory(ast_value_factory_);
+      factory.set_zone(zone_);
+      VariableProxy* variable =
+          factory.NewVariableProxy(identifier.string_, NORMAL_VARIABLE);
+      expression.AddVariable(variable, zone_);
+    }

[neis, 2016/12/12 13:01:36]

Why do we create a variable proxy for a string literal?

[marja, 2016/12/12 13:36:46]

Discussed offline: for object literal properties which through this code path
(see comment above).

     return expression;
   }
   PreParserExpression NewNumberLiteral(double number,
@@ -552,7 +561,7 @@ class PreParserFactory {
   PreParserExpression NewArrayLiteral(PreParserExpressionList values,
                                       int first_spread_index, int literal_index,
                                       int pos) {
-    return PreParserExpression::ArrayLiteral(values.identifiers_);
+    return PreParserExpression::ArrayLiteral(values.variables_);
   }
   PreParserExpression NewClassLiteralProperty(PreParserExpression key,
                                               PreParserExpression value,
@@ -565,18 +574,18 @@ class PreParserFactory {
                                                PreParserExpression value,
                                                ObjectLiteralProperty::Kind kind,
                                                bool is_computed_name) {
-    return PreParserExpression::Default(value.identifiers_);
+    return PreParserExpression::Default(value.variables_);
   }
   PreParserExpression NewObjectLiteralProperty(PreParserExpression key,
                                                PreParserExpression value,
                                                bool is_computed_name) {
-    return PreParserExpression::Default(value.identifiers_);
+    return PreParserExpression::Default(value.variables_);
   }
   PreParserExpression NewObjectLiteral(PreParserExpressionList properties,
                                        int literal_index,
                                        int boilerplate_properties,
                                        int pos) {
-    return PreParserExpression::ObjectLiteral(properties.identifiers_);
+    return PreParserExpression::ObjectLiteral(properties.variables_);
   }
   PreParserExpression NewVariableProxy(void* variable) {
     return PreParserExpression::Default();
@@ -611,8 +620,8 @@ class PreParserFactory {
                                     PreParserExpression left,
                                     PreParserExpression right,
                                     int pos) {
-    // For tracking identifiers for parameters with a default value.
-    return PreParserExpression::Assignment(left.identifiers_);
+    // For tracking variables for parameters with a default value.
+    return PreParserExpression::Assignment(left.variables_);
   }
   PreParserExpression NewYield(PreParserExpression generator_object,
                                PreParserExpression expression, int pos,
@@ -749,6 +758,7 @@ class PreParserFactory {
   }
 
  private:
+  AstValueFactory* ast_value_factory_;
   Zone* zone_;
 };
 
@@ -1211,10 +1221,16 @@ class PreParser : public ParserBase<PreParser> {
   V8_INLINE static void CheckAssigningFunctionLiteralToProperty(
       PreParserExpression left, PreParserExpression right) {}
 
-  V8_INLINE static void MarkExpressionAsAssigned(
-      PreParserExpression expression) {
+  V8_INLINE void MarkExpressionAsAssigned(PreParserExpression expression) {
     // TODO(marja): To be able to produce the same errors, the preparser needs
     // to start tracking which expressions are variables and which are assigned.

[neis, 2016/12/12 13:01:36]

Is this TODO now resolved?

[marja, 2016/12/12 13:36:46]

Sadly, no. It's orthogonal-ish. We still only track the variables in the
track_unresolved_variables_ = true mode, and don't track them in a way that
would allow us to produce all the errors.. (and error producing is not
implemented).

+    if (expression.variables_ != nullptr) {
+      DCHECK(FLAG_lazy_inner_functions);
+      DCHECK(track_unresolved_variables_);
+      for (auto variable : *expression.variables_) {
+        variable->set_is_assigned();
+      }
+    }
   }
 
   V8_INLINE bool ShortcutNumericLiteralBinaryExpression(PreParserExpression* x,
@@ -1244,6 +1260,7 @@ class PreParser : public ParserBase<PreParser> {
   InitializeForEachStatement(PreParserStatement stmt, PreParserExpression each,
                              PreParserExpression subject,
                              PreParserStatement body, int each_keyword_pos) {
+    MarkExpressionAsAssigned(each);

[neis, 2016/12/12 13:01:36]

Maybe reflect this change in the CL description.

[marja, 2016/12/12 13:36:46]

Offline discussion: this falls under the description.

     return stmt;
   }
 
@@ -1474,9 +1491,9 @@ class PreParser : public ParserBase<PreParser> {
     if (track_unresolved_variables_) {
       DCHECK(FLAG_lazy_inner_functions);
       for (auto parameter : parameters) {
-        if (parameter->pattern.identifiers_ != nullptr) {
-          for (auto i : *parameter->pattern.identifiers_) {
-            scope->DeclareVariableName(i, VAR);
+        if (parameter->pattern.variables_ != nullptr) {
+          for (auto variable : *parameter->pattern.variables_) {
+            scope->DeclareVariableName(variable->raw_name(), VAR);
           }
         }
       }
@@ -1511,7 +1528,7 @@ class PreParser : public ParserBase<PreParser> {
 
   V8_INLINE PreParserExpression
   ExpressionListToExpression(PreParserExpressionList args) {
-    return PreParserExpression::Default(args.identifiers_);
+    return PreParserExpression::Default(args.variables_);
   }
 
   V8_INLINE void AddAccessorPrefixToFunctionName(bool is_get,