Teach Scopes whether they will end up being lazily compiled or not

src/parsing/parser.cc

 // Copyright 2012 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/parsing/parser.h"
 
 #include <memory>
 
 #include "src/api.h"
 #include "src/ast/ast-expression-rewriter.h"
@@ skipping 266 matching lines @@
     }
 
     materialized_literal_count = function_state.materialized_literal_count();
     expected_property_count = function_state.expected_property_count();
   }
 
   FunctionLiteral* function_literal = factory()->NewFunctionLiteral(
       name, function_scope, body, materialized_literal_count,
       expected_property_count, parameter_count,
       FunctionLiteral::kNoDuplicateParameters,
-      FunctionLiteral::kAnonymousExpression,
-      FunctionLiteral::kShouldLazyCompile, pos);
+      FunctionLiteral::kAnonymousExpression, default_eager_compile_hint(), pos);
 
   function_literal->set_requires_class_field_init(requires_class_field_init);
 
   return function_literal;
 }
 
 
 // ----------------------------------------------------------------------------
 // Target is a support class to facilitate manipulation of the
 // Parser's target_stack_ (the stack of potential 'break' and
@@ skipping 340 matching lines @@
       compile_options_(info->compile_options()),
       cached_parse_data_(NULL),
       total_preparse_skipped_(0),
       pre_parse_timer_(NULL),
       parsing_on_main_thread_(true) {
   // Even though we were passed ParseInfo, we should not store it in
   // Parser - this makes sure that Isolate is not accidentally accessed via
   // ParseInfo during background parsing.
   DCHECK(!info->script().is_null() || info->source_stream() != nullptr ||
          info->character_stream() != nullptr);
+  // Determine if functions can be lazily compiled. This is necessary to
+  // allow some of our builtin JS files to be lazily compiled. These
+  // builtins cannot be handled lazily by the parser, since we have to know
+  // if a function uses the special natives syntax, which is something the
+  // parser records.
+  // If the debugger requests compilation for break points, we cannot be
+  // aggressive about lazy compilation, because it might trigger compilation
+  // of functions without an outer context when setting a breakpoint through
+  // Debug::FindSharedFunctionInfoInScript
+  bool can_compile_lazily = FLAG_lazy && !info->is_debug();
+
+  // Consider compiling eagerly when targeting the code cache.
+  can_compile_lazily &= !(FLAG_serialize_eager && info->will_serialize());
+
+  // Consider compiling eagerly when compiling bytecode for Ignition.
+  can_compile_lazily &= !(FLAG_ignition && FLAG_ignition_eager &&
+                          info->isolate()->serializer_enabled());
+
+  set_default_eager_compile_hint(can_compile_lazily
+                                     ? FunctionLiteral::kShouldLazyCompile
+                                     : FunctionLiteral::kShouldEagerCompile);
   set_allow_lazy(FLAG_lazy && info->allow_lazy_parsing() &&
                  !info->is_native() && info->extension() == nullptr);
   set_allow_natives(FLAG_allow_natives_syntax || info->is_native());
   set_allow_tailcalls(FLAG_harmony_tailcalls && !info->is_native() &&
                       info->isolate()->is_tail_call_elimination_enabled());
   set_allow_harmony_do_expressions(FLAG_harmony_do_expressions);
   set_allow_harmony_for_in(FLAG_harmony_for_in);
   set_allow_harmony_function_sent(FLAG_harmony_function_sent);
   set_allow_harmony_restrictive_declarations(
       FLAG_harmony_restrictive_declarations);
@@ skipping 1900 matching lines @@
   bool should_infer_name = function_name == NULL;
 
   // We want a non-null handle as the function name.
   if (should_infer_name) {
     function_name = ast_value_factory()->empty_string();
   }
 
   FunctionLiteral::EagerCompileHint eager_compile_hint =
       function_state_->next_function_is_parenthesized()
           ? FunctionLiteral::kShouldEagerCompile
-          : FunctionLiteral::kShouldLazyCompile;
+          : default_eager_compile_hint();
 
   // Determine if the function can be parsed lazily. Lazy parsing is
   // different from lazy compilation; we need to parse more eagerly than we
   // compile.
 
   // We can only parse lazily if we also compile lazily. The heuristics for lazy
   // compilation are:
   // - It must not have been prohibited by the caller to Parse (some callers
   //   need a full AST).
   // - The outer scope must allow lazy compilation of inner functions.
@@ skipping 2862 matching lines @@
 
   return final_loop;
 }
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8