Parsing: Create the same scopes for non-simple params in PreParser & Parser.

Rationale:

- To do scope analysis based on PreParser, and use the result again when parsing
  later, PreParser and Parser need to produce the same Scopes and variable
  declarations in them.

- This is not the case for non-simple parameters: Parser creates an additional
  inner Scope where the declarations were, whereas PreParser does
  DeclareVariableName directly in the function Scope.

- So this CL fixes that by moving the Scope creation for non-simple parameters
  into ParserBase.

- As a side product (and a partial proof that this change makes sense),
  PreParser::ParseEagerFunctionBody is now gone.

BUG=v8:5516

Review-Url: https://codereview.chromium.org/2638333002
Cr-Commit-Position: refs/heads/master@{#42537}

src/parsing/parser-base.h

@@ -101,6 +101,12 @@ struct FormalParametersBase {
 // Used in functions where the return type is ExpressionT.
 #define CHECK_OK CHECK_OK_CUSTOM(EmptyExpression)
 
+#define CHECK_OK_VOID ok); \
+  if (!*ok) return;        \
+  ((void)0
+#define DUMMY )  // to make indentation work
+#undef DUMMY
+
 // Common base class template shared between parser and pre-parser.
 // The Impl parameter is the actual class of the parser/pre-parser,
 // following the Curiously Recurring Template Pattern (CRTP).
@@ -1224,6 +1230,12 @@ class ParserBase {
                                    bool default_export, bool* ok);
   StatementT ParseNativeDeclaration(bool* ok);
 
+  // Consumes the ending }.
+  void ParseFunctionBody(StatementListT result, IdentifierT function_name,
+                         int pos, const FormalParametersT& parameters,
+                         FunctionKind kind,
+                         FunctionLiteral::FunctionType function_type, bool* ok);
+
   // Under some circumstances, we allow preparsing to abort if the preparsed
   // function is "long and trivial", and fully parse instead. Our current
   // definition of "long and trivial" is:
@@ -3901,6 +3913,105 @@ ParserBase<Impl>::ParseAsyncFunctionDeclaration(
   return ParseHoistableDeclaration(pos, flags, names, default_export, ok);
 }
 
+template <typename Impl>
+void ParserBase<Impl>::ParseFunctionBody(
+    typename ParserBase<Impl>::StatementListT result, IdentifierT function_name,
+    int pos, const FormalParametersT& parameters, FunctionKind kind,
+    FunctionLiteral::FunctionType function_type, bool* ok) {
+  static const int kFunctionNameAssignmentIndex = 0;
+  if (function_type == FunctionLiteral::kNamedExpression) {
+    DCHECK(!impl()->IsEmptyIdentifier(function_name));
+    // If we have a named function expression, we add a local variable
+    // declaration to the body of the function with the name of the
+    // function and let it refer to the function itself (closure).
+    // Not having parsed the function body, the language mode may still change,
+    // so we reserve a spot and create the actual const assignment later.
+    DCHECK_EQ(kFunctionNameAssignmentIndex, result->length());
+    result->Add(impl()->NullStatement(), zone());
+  }
+
+  DeclarationScope* function_scope = scope()->AsDeclarationScope();
+  DeclarationScope* inner_scope = function_scope;
+  BlockT inner_block = impl()->NullBlock();
+
+  StatementListT body = result;
+  if (!parameters.is_simple) {
+    inner_scope = NewVarblockScope();
+    inner_scope->set_start_position(scanner()->location().beg_pos);
+    inner_block = factory()->NewBlock(NULL, 8, true, kNoSourcePosition);
+    inner_block->set_scope(inner_scope);
+    body = inner_block->statements();
+  }
+
+  {
+    BlockState block_state(&scope_state_, inner_scope);
+
+    if (IsGeneratorFunction(kind)) {
+      impl()->ParseAndRewriteGeneratorFunctionBody(pos, kind, body, ok);
+    } else if (IsAsyncFunction(kind)) {
+      const bool accept_IN = true;
+      ParseAsyncFunctionBody(inner_scope, body, kind, FunctionBodyType::kNormal,
+                             accept_IN, pos, CHECK_OK_VOID);
+    } else {
+      ParseStatementList(body, Token::RBRACE, CHECK_OK_VOID);
+    }
+
+    if (IsDerivedConstructor(kind)) {
+      body->Add(factory()->NewReturnStatement(impl()->ThisExpression(),
+                                              kNoSourcePosition),
+                zone());
+    }
+  }
+
+  Expect(Token::RBRACE, CHECK_OK_VOID);
+  scope()->set_end_position(scanner()->location().end_pos);
+
+  if (!parameters.is_simple) {
+    DCHECK_NOT_NULL(inner_scope);
+    DCHECK_EQ(function_scope, scope());
+    DCHECK_EQ(function_scope, inner_scope->outer_scope());
+    impl()->SetLanguageMode(function_scope, inner_scope->language_mode());
+    BlockT init_block =
+        impl()->BuildParameterInitializationBlock(parameters, CHECK_OK_VOID);
+
+    if (is_sloppy(inner_scope->language_mode())) {
+      impl()->InsertSloppyBlockFunctionVarBindings(inner_scope);
+    }
+
+    // TODO(littledan): Merge the two rejection blocks into one
+    if (IsAsyncFunction(kind)) {
+      init_block = impl()->BuildRejectPromiseOnException(init_block);
+    }
+
+    inner_scope->set_end_position(scanner()->location().end_pos);
+    if (inner_scope->FinalizeBlockScope() != nullptr) {
+      impl()->CheckConflictingVarDeclarations(inner_scope, CHECK_OK_VOID);
+      impl()->InsertShadowingVarBindingInitializers(inner_block);
+    }
+    inner_scope = nullptr;
+
+    result->Add(init_block, zone());
+    result->Add(inner_block, zone());
+  } else {
+    DCHECK_EQ(inner_scope, function_scope);
+    if (is_sloppy(function_scope->language_mode())) {
+      impl()->InsertSloppyBlockFunctionVarBindings(function_scope);
+    }
+  }
+
+  if (!IsArrowFunction(kind)) {
+    // Declare arguments after parsing the function since lexical 'arguments'
+    // masks the arguments object. Declare arguments before declaring the
+    // function var since the arguments object masks 'function arguments'.
+    function_scope->DeclareArguments(ast_value_factory());
+  }
+
+  impl()->CreateFunctionNameAssignment(function_name, pos, function_type,
+                                       function_scope, result,
+                                       kFunctionNameAssignmentIndex);
+  impl()->MarkCollectedTailCallExpressions();
+}
+
 template <typename Impl>
 void ParserBase<Impl>::CheckArityRestrictions(int param_count,
                                               FunctionKind function_kind,
@@ -4064,9 +4175,11 @@ ParserBase<Impl>::ParseArrowFunctionLiteral(
       }
       if (!is_lazy_top_level_function) {
         Consume(Token::LBRACE);
-        body = impl()->ParseEagerFunctionBody(
-            impl()->EmptyIdentifier(), kNoSourcePosition, formal_parameters,
-            kind, FunctionLiteral::kAnonymousExpression, CHECK_OK);
+        body = impl()->NewStatementList(8);
+        impl()->ParseFunctionBody(body, impl()->EmptyIdentifier(),
+                                  kNoSourcePosition, formal_parameters, kind,
+                                  FunctionLiteral::kAnonymousExpression,
+                                  CHECK_OK);
         materialized_literal_count =
             function_state.materialized_literal_count();
         expected_property_count = function_state.expected_property_count();
@@ -5563,6 +5676,7 @@ void ParserBase<Impl>::ClassLiteralChecker::CheckClassMethodName(
   }
 }
 
+#undef CHECK_OK_VOID
 
 }  // namespace internal
 }  // namespace v8

src/parsing/parser.h

@@ -340,6 +340,14 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
                                  Block* finally_block,
                                  const CatchInfo& catch_info, int pos);
 
+  void ParseAndRewriteGeneratorFunctionBody(int pos, FunctionKind kind,
+                                            ZoneList<Statement*>* body,
+                                            bool* ok);
+  void CreateFunctionNameAssignment(const AstRawString* function_name, int pos,
+                                    FunctionLiteral::FunctionType function_type,
+                                    DeclarationScope* function_scope,
+                                    ZoneList<Statement*>* result, int index);
+
   Statement* DeclareFunction(const AstRawString* variable_name,
                              FunctionLiteral* function, VariableMode mode,
                              int pos, bool is_generator, bool is_async,
@@ -533,13 +541,7 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
 
   Block* BuildParameterInitializationBlock(
       const ParserFormalParameters& parameters, bool* ok);
-  Block* BuildRejectPromiseOnException(Block* block, bool* ok);
-
-  // Consumes the ending }.
-  ZoneList<Statement*>* ParseEagerFunctionBody(
-      const AstRawString* function_name, int pos,
-      const ParserFormalParameters& parameters, FunctionKind kind,
-      FunctionLiteral::FunctionType function_type, bool* ok);
+  Block* BuildRejectPromiseOnException(Block* block);
 
   ZoneList<Statement*>* ParseFunction(
       const AstRawString* function_name, int pos, FunctionKind kind,
@@ -1025,8 +1027,7 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
     auto* init_block = BuildParameterInitializationBlock(parameters, ok);
     if (!*ok) return;
     if (is_async) {
-      init_block = BuildRejectPromiseOnException(init_block, ok);
-      if (!*ok) return;
+      init_block = BuildRejectPromiseOnException(init_block);
     }
     if (init_block != nullptr) body->Add(init_block, zone());
   }

src/parsing/preparser.h

@@ -414,10 +414,11 @@ class PreParserList {
   // These functions make list->Add(some_expression) work (and do nothing).
   PreParserList() : length_(0), variables_(nullptr) {}
   PreParserList* operator->() { return this; }
-  void Add(T, Zone* zone);
+  void Add(const T& element, Zone* zone);
   int length() const { return length_; }
   static PreParserList Null() { return PreParserList(-1); }
   bool IsNull() const { return length_ == -1; }
+  void Set(int index, const T& element) {}
 
  private:
   explicit PreParserList(int n) : length_(n), variables_(nullptr) {}
@@ -430,7 +431,7 @@ class PreParserList {
 
 template <>
 inline void PreParserList<PreParserExpression>::Add(
-    PreParserExpression expression, Zone* zone) {
+    const PreParserExpression& expression, Zone* zone) {
   if (expression.variables_ != nullptr) {
     DCHECK(FLAG_lazy_inner_functions);
     DCHECK(zone != nullptr);
@@ -445,7 +446,7 @@ inline void PreParserList<PreParserExpression>::Add(
 }
 
 template <typename T>
-void PreParserList<T>::Add(T, Zone* zone) {
+void PreParserList<T>::Add(const T& element, Zone* zone) {
   ++length_;
 }
 
@@ -939,11 +940,6 @@ class PreParser : public ParserBase<PreParser> {
   // By making the 'exception handling' explicit, we are forced to check
   // for failure at the call sites.
 
-  V8_INLINE PreParserStatementList ParseEagerFunctionBody(
-      PreParserIdentifier function_name, int pos,
-      const PreParserFormalParameters& parameters, FunctionKind kind,
-      FunctionLiteral::FunctionType function_type, bool* ok);
-
   // Indicates that we won't switch from the preparser to the preparser; we'll
   // just stay where we are.
   bool AllowsLazyParsingWithoutUnresolvedVariables() const { return false; }
@@ -1075,6 +1071,16 @@ class PreParser : public ParserBase<PreParser> {
     return PreParserStatement::Default();
   }
 
+  V8_INLINE void ParseAndRewriteGeneratorFunctionBody(
+      int pos, FunctionKind kind, PreParserStatementList body, bool* ok) {
+    ParseStatementList(body, Token::RBRACE, ok);
+  }
+  V8_INLINE void CreateFunctionNameAssignment(
+      PreParserIdentifier function_name, int pos,
+      FunctionLiteral::FunctionType function_type,
+      DeclarationScope* function_scope, PreParserStatementList result,
+      int index) {}
+
   V8_INLINE PreParserExpression RewriteDoExpression(PreParserStatement body,
                                                     int pos, bool* ok) {
     return PreParserExpression::Default();
@@ -1328,6 +1334,23 @@ class PreParser : public ParserBase<PreParser> {
     return loop;
   }
 
+  V8_INLINE PreParserStatement BuildParameterInitializationBlock(
+      const PreParserFormalParameters& parameters, bool* ok) {
+    return PreParserStatement::Default();
+  }
+
+  V8_INLINE PreParserStatement
+  BuildRejectPromiseOnException(PreParserStatement init_block) {
+    return PreParserStatement::Default();
+  }
+
+  V8_INLINE void InsertSloppyBlockFunctionVarBindings(DeclarationScope* scope) {
+    scope->HoistSloppyBlockFunctions(nullptr);
+  }
+
+  V8_INLINE void InsertShadowingVarBindingInitializers(
+      PreParserStatement block) {}
+
   V8_INLINE PreParserExpression
   NewThrowReferenceError(MessageTemplate::Template message, int pos) {
     return PreParserExpression::Default();
@@ -1623,29 +1646,6 @@ PreParserExpression PreParser::SpreadCallNew(PreParserExpression function,
   return factory()->NewCallNew(function, args, pos);
 }
 
-PreParserStatementList PreParser::ParseEagerFunctionBody(
-    PreParserIdentifier function_name, int pos,
-    const PreParserFormalParameters& parameters, FunctionKind kind,
-    FunctionLiteral::FunctionType function_type, bool* ok) {
-  PreParserStatementList result;
-
-  DeclarationScope* inner_scope = scope()->AsDeclarationScope();
-  if (!parameters.is_simple) inner_scope = NewVarblockScope();
-
-  {
-    BlockState block_state(&scope_state_, inner_scope);
-    ParseStatementList(result, Token::RBRACE, ok);
-    if (!*ok) return PreParserStatementList();
-  }
-
-  Expect(Token::RBRACE, ok);
-
-  if (is_sloppy(inner_scope->language_mode())) {
-    inner_scope->HoistSloppyBlockFunctions(nullptr);
-  }
-  return result;
-}
-
 PreParserExpression PreParser::CloseTemplateLiteral(TemplateLiteralState* state,
                                                     int start,
                                                     PreParserExpression tag) {