[wasm] asm.js - Parse and convert asm.js to wasm a function at a time.

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 837 matching lines @@
                                       &RuntimeCallStats::ParseFunction);
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.ParseFunction");
   Handle<String> source(String::cast(info->script()->source()));
   isolate->counters()->total_parse_size()->Increment(source->length());
   base::ElapsedTimer timer;
   if (FLAG_trace_parse) {
     timer.Start();
   }
   Handle<SharedFunctionInfo> shared_info = info->shared_info();
   DeserializeScopeChain(info, info->maybe_outer_scope_info());
+  if (info->asm_function_scope()) {

[titzer, 2016/11/28 10:40:11]

Also fishy. I am not sure why we have to manually mess with the scope chain
here.

[bradn, 2016/11/29 06:30:35]

Agreed.
I had tried instead to set the outer function on the ParseInfo,
but DeserializeScopeChain assumes that outer scopes are fully resolved in
various way:
* Have slots assigned to them
* Aren't going to be disconnected from the chain

To be honest I'm a little fuzzy on what deserialization means in this context?

+    original_scope_ = info->asm_function_scope();
+  }
 
   // Initialize parser state.
   source = String::Flatten(source);
   FunctionLiteral* result;
   {
     std::unique_ptr<Utf16CharacterStream> stream(ScannerStream::For(
         source, shared_info->start_position(), shared_info->end_position()));
     Handle<String> name(String::cast(shared_info->name()));
     result = DoParseFunction(info, ast_value_factory()->GetString(name),
                              stream.get());
@@ skipping 1735 matching lines @@
   // - Neither V8 natives nor native function declarations can be allowed,
   //   since parsing one would retroactively force the function to be
   //   eagerly compiled.
   // - The invoker of this parser can't depend on the AST being eagerly
   //   built (either because the function is about to be compiled, or
   //   because the AST is going to be inspected for some reason).
   // - Because of the above, we can't be attempting to parse a
   //   FunctionExpression; even without enclosing parentheses it might be
   //   immediately invoked.
   // - The function literal shouldn't be hinted to eagerly compile.
-  // - For asm.js functions the body needs to be available when module
-  //   validation is active, because we examine the entire module at once.
 
   // Inner functions will be parsed using a temporary Zone. After parsing, we
   // will migrate unresolved variable into a Scope in the main Zone.
   // TODO(marja): Refactor parsing modes: simplify this.
   bool use_temp_zone =
       (FLAG_lazy_inner_functions
            ? can_preparse
            : (is_lazy_top_level_function ||
               (allow_lazy_ && function_type == FunctionLiteral::kDeclaration &&
-               eager_compile_hint == FunctionLiteral::kShouldLazyCompile))) &&
-      !(FLAG_validate_asm && scope()->IsAsmModule());
+               eager_compile_hint == FunctionLiteral::kShouldLazyCompile)));
   bool is_lazy_inner_function =
       use_temp_zone && FLAG_lazy_inner_functions && !is_lazy_top_level_function;
 
   ZoneList<Statement*>* body = nullptr;
   int materialized_literal_count = -1;
   int expected_property_count = -1;
   bool should_be_used_once_hint = false;
   int num_parameters = -1;
   int function_length = -1;
   bool has_duplicate_parameters = false;
@@ skipping 2836 matching lines @@
 
   return final_loop;
 }
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8