[interpreter] Add ability to preserve bytecode.

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 975 matching lines @@
   // Compile baseline code using the full code generator.
   if (!Compiler::Analyze(info.parse_info()) ||
       !FullCodeGenerator::MakeCode(&info)) {
     if (!isolate->has_pending_exception()) isolate->StackOverflow();
     return MaybeHandle<Code>();
   }
 
   // TODO(4280): For now we play it safe and remove the bytecode array when we
   // switch to baseline code. We might consider keeping around the bytecode so
   // that it can be used as the "source of truth" eventually.
-  shared->ClearBytecodeArray();
+  if (!FLAG_ignition_preserve_bytecode) shared->ClearBytecodeArray();
 
   // Update the shared function info with the scope info.
   InstallSharedScopeInfo(&info, shared);
 
   // Install compilation result on the shared function info
   InstallSharedCompilationResult(&info, shared);
 
   // Record the function compilation event.
   RecordFunctionCompilation(CodeEventListener::LAZY_COMPILE_TAG, &info);
 
@@ skipping 420 matching lines @@
     if (shared->code()->kind() == Code::FUNCTION &&
         shared->code()->has_reloc_info_for_serialization()) {
       unoptimized.PrepareForSerializing();
     }
     EnsureFeedbackMetadata(&unoptimized);
     if (!FullCodeGenerator::MakeCode(&unoptimized)) return false;
 
     // TODO(4280): For now we play it safe and remove the bytecode array when we
     // switch to baseline code. We might consider keeping around the bytecode so
     // that it can be used as the "source of truth" eventually.
-    shared->ClearBytecodeArray();
+    if (!FLAG_ignition_preserve_bytecode) shared->ClearBytecodeArray();
 
     // The scope info might not have been set if a lazily compiled
     // function is inlined before being called for the first time.
     if (shared->scope_info() == ScopeInfo::Empty(info->isolate())) {
       InstallSharedScopeInfo(info, shared);
     }
 
     // Install compilation result on the shared function info
     shared->EnableDeoptimizationSupport(*unoptimized.code());
 
@@ skipping 502 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