Allow lazy parsing of functions nested in eager compiled functions

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 6b21a6fe50009f62dc674e1f3b98af87d6bb44d7..0b4037160261b7aa8413f7610f5bbfa6f87ab0b3 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -2624,10 +2624,11 @@ FunctionLiteral* Parser::ParseFunctionLiteral(
   DCHECK_IMPLIES(mode() == PARSE_LAZILY, allow_lazy());
   DCHECK_IMPLIES(mode() == PARSE_LAZILY, extension_ == nullptr);
 
+  bool can_preparse = mode() == PARSE_LAZILY &&
+                      eager_compile_hint == FunctionLiteral::kShouldLazyCompile;
+
   bool is_lazy_top_level_function =
-      mode() == PARSE_LAZILY &&
-      eager_compile_hint == FunctionLiteral::kShouldLazyCompile &&
-      scope()->AllowsLazyParsingWithoutUnresolvedVariables();
+      can_preparse && scope()->AllowsLazyParsingWithoutUnresolvedVariables();
 
   // Determine whether we can still lazy parse the inner function.
   // The preconditions are:
@@ -2649,8 +2650,10 @@ FunctionLiteral* Parser::ParseFunctionLiteral(
   // will migrate unresolved variable into a Scope in the main Zone.
   // TODO(marja): Refactor parsing modes: simplify this.
   bool use_temp_zone =
-      allow_lazy() && function_type == FunctionLiteral::kDeclaration &&
-      eager_compile_hint != FunctionLiteral::kShouldEagerCompile &&
+      (FLAG_lazy_inner_functions

[marja, 2016/10/11 07:56:47]

You're dropping the function_type == FunctionLiteral::kDeclaration condition
here. Why?

What's the invariant - is this supposed to keep the current behavior whenever
!FLAG_lazy_inner_functions?

[Toon Verwaest, 2016/10/11 10:44:00]

I don't see the reason why FunctionLiteral::kDeclaration was there in the first
place mostly. The invariant is that we shouldn't temp-zone parse if allow_lazy()
is set to false; which is currently true when we "ParseLazy" (parse a function).
I'm ok with putting it back, but I don't think it's necessary.

+           ? can_preparse
+           : (allow_lazy() &&
+              eager_compile_hint == FunctionLiteral::kShouldLazyCompile)) &&
       !(FLAG_validate_asm && scope()->IsAsmModule());
   bool is_lazy_inner_function =
       use_temp_zone && FLAG_lazy_inner_functions && !is_lazy_top_level_function;
@@ -3150,11 +3153,7 @@ ZoneList<Statement*>* Parser::ParseEagerFunctionBody(
     const AstRawString* function_name, int pos,
     const ParserFormalParameters& parameters, FunctionKind kind,
     FunctionLiteral::FunctionType function_type, bool* ok) {
-  // Everything inside an eagerly parsed function will be parsed eagerly (see
-  // comment above). Lazy inner functions are handled separately and they won't
-  // require the mode to be PARSE_LAZILY (see ParseFunctionLiteral).
-  // TODO(marja): Refactor parsing modes: remove this.
-  ParsingModeScope parsing_mode(this, PARSE_EAGERLY);
+  ParsingModeScope mode(this, allow_lazy() ? PARSE_LAZILY : PARSE_EAGERLY);
   ZoneList<Statement*>* result = new(zone()) ZoneList<Statement*>(8, zone());
 
   static const int kFunctionNameAssignmentIndex = 0;