[compiler] Don't canonicalize handles in Crankshaft.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 00beeb6ef621f75d029e8136081b533f81230664..4ba9fcea5fc5f40e3ff2ed74ca2dee81f5bb2f83 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -698,7 +698,7 @@ bool GetOptimizedCodeNow(CompilationJob* job) {
   return true;
 }
 
-bool GetOptimizedCodeLater(CompilationJob* job) {
+bool GetOptimizedCodeLater(CompilationJob* job, bool use_turbofan) {
   CompilationInfo* info = job->info();
   Isolate* isolate = info->isolate();
 
@@ -724,7 +724,8 @@ bool GetOptimizedCodeLater(CompilationJob* job) {
   // deferred handle scope that is detached and handed off to the background
   // thread when we return.
   CompilationHandleScope handle_scope(info);

[Michael Starzinger, 2016/08/25 11:44:20]

Would it be possible to hoist both, the CompilationHandleScope as well as the
CannonicalHandleScope out into the caller. There the usr_turbofan predicate us
available without passing it around magically. Also it would allow us to see
that GetOptimizedCodeNow is in sync.

-  CanonicalHandleScope canonical(isolate);
+  std::unique_ptr<CanonicalHandleScope> canonical;
+  if (use_turbofan) canonical.reset(new CanonicalHandleScope(info->isolate()));
 
   // Parsing is not required when optimizing from existing bytecode.
   if (!info->is_optimizing_from_bytecode()) {
@@ -840,7 +841,7 @@ MaybeHandle<Code> GetOptimizedCode(Handle<JSFunction> function,
   }
 
   if (mode == Compiler::CONCURRENT) {
-    if (GetOptimizedCodeLater(job.get())) {
+    if (GetOptimizedCodeLater(job.get(), use_turbofan)) {
       job.release();  // The background recompile job owns this now.
       return isolate->builtins()->InOptimizationQueue();
     }