[Interpreter] Avoid dereferencing handles on BytecodeGenerator for AST operations.

src/compiler.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/compiler.h"
 
 #include <algorithm>
 #include <memory>
 
 #include "src/asmjs/asm-js.h"
@@ skipping 522 matching lines @@
   if (info->has_bytecode_array()) {
     DCHECK(!shared->HasBytecodeArray());  // Only compiled once.
     shared->set_bytecode_array(*info->bytecode_array());
   }
 }
 
 MUST_USE_RESULT MaybeHandle<Code> GetUnoptimizedCode(CompilationInfo* info) {
   VMState<COMPILER> state(info->isolate());
   PostponeInterruptsScope postpone(info->isolate());
 
-  // Create a canonical handle scope if compiling ignition bytecode. This is
-  // required by the constant array builder to de-duplicate common objects
-  // without dereferencing handles.
+  // Create a canonical handle scope before internalizing parsed values if
+  // compiling bytecode. This is required for off-thread bytecode generation.
   std::unique_ptr<CanonicalHandleScope> canonical;
   if (FLAG_ignition) canonical.reset(new CanonicalHandleScope(info->isolate()));
 
   // Parse and update CompilationInfo with the results.
   if (!Parser::ParseStatic(info->parse_info())) return MaybeHandle<Code>();
   Handle<SharedFunctionInfo> shared = info->shared_info();
   DCHECK_EQ(shared->language_mode(), info->literal()->language_mode());
 
   // Compile either unoptimized code or bytecode for the interpreter.
   if (!CompileUnoptimizedCode(info)) return MaybeHandle<Code>();
@@ skipping 511 matching lines @@
 Handle<SharedFunctionInfo> CompileToplevel(CompilationInfo* info) {
   Isolate* isolate = info->isolate();
   TimerEventScope<TimerEventCompileCode> timer(isolate);
   RuntimeCallTimerScope runtimeTimer(isolate, &RuntimeCallStats::CompileCode);
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.CompileCode");
   PostponeInterruptsScope postpone(isolate);
   DCHECK(!isolate->native_context().is_null());
   ParseInfo* parse_info = info->parse_info();
   Handle<Script> script = parse_info->script();
 
-  // Create a canonical handle scope if compiling ignition bytecode. This is
-  // required by the constant array builder to de-duplicate common objects
-  // without dereferencing handles.
+  // Create a canonical handle scope before internalizing parsed values if
+  // compiling bytecode. This is required for off-thread bytecode generation.
   std::unique_ptr<CanonicalHandleScope> canonical;
   if (FLAG_ignition) canonical.reset(new CanonicalHandleScope(isolate));
 
   // TODO(svenpanne) Obscure place for this, perhaps move to OnBeforeCompile?
   FixedArray* array = isolate->native_context()->embedder_data();
   script->set_context_data(array->get(v8::Context::kDebugIdIndex));
 
   isolate->debug()->OnBeforeCompile(script);
 
   DCHECK(parse_info->is_eval() || parse_info->is_global() ||
@@ skipping 854 matching lines @@
     DCHECK(shared->is_compiled());
     function->set_literals(cached.literals);
   } else if (shared->is_compiled()) {
     // TODO(mvstanton): pass pretenure flag to EnsureLiterals.
     JSFunction::EnsureLiterals(function);
   }
 }
 
 }  // namespace internal
 }  // namespace v8