Switch GetConcurrentlyOptimizedCode to MaybeHandle.

The function in question can already return an empty handle in the case
of failures. This makes that contract explicit by using MaybeHandle like
all other compiler API functions.

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/1590963002

Cr-Commit-Position: refs/heads/master@{#33839}

src/compiler.cc

@@ -1784,8 +1784,8 @@ MaybeHandle<Code> Compiler::GetOptimizedCode(Handle<JSFunction> function,
   return MaybeHandle<Code>();
 }
 
-
-Handle<Code> Compiler::GetConcurrentlyOptimizedCode(OptimizedCompileJob* job) {
+MaybeHandle<Code> Compiler::GetConcurrentlyOptimizedCode(
+    OptimizedCompileJob* job) {
   // Take ownership of compilation info.  Deleting compilation info
   // also tears down the zone and the recompile job.
   base::SmartPointer<CompilationInfo> info(job->info());
@@ -1830,7 +1830,7 @@ Handle<Code> Compiler::GetConcurrentlyOptimizedCode(OptimizedCompileJob* job) {
     info->closure()->ShortPrint();
     PrintF(" because: %s]\n", GetBailoutReason(info->bailout_reason()));
   }
-  return Handle<Code>::null();
+  return MaybeHandle<Code>();
 }
 
 

src/compiler.h

@@ -637,7 +637,8 @@ class Compiler : public AllStatic {
 
   // Generate and return code from previously queued optimization job.
   // On failure, return the empty handle.
-  static Handle<Code> GetConcurrentlyOptimizedCode(OptimizedCompileJob* job);
+  MUST_USE_RESULT static MaybeHandle<Code> GetConcurrentlyOptimizedCode(
+      OptimizedCompileJob* job);
 };
 
 

src/optimizing-compile-dispatcher.cc

@@ -244,9 +244,9 @@ void OptimizingCompileDispatcher::InstallOptimizedFunctions() {
         }
         DisposeOptimizedCompileJob(job, false);
       } else {
-        Handle<Code> code = Compiler::GetConcurrentlyOptimizedCode(job);
+        MaybeHandle<Code> code = Compiler::GetConcurrentlyOptimizedCode(job);
         function->ReplaceCode(code.is_null() ? function->shared()->code()
-                                             : *code);
+                                             : *code.ToHandleChecked());
       }
     }
   }

src/runtime/runtime-compiler.cc

@@ -248,7 +248,6 @@ RUNTIME_FUNCTION(Runtime_CompileForOnStackReplacement) {
                                     function->shared()->ast_node_count() > 512)
                                        ? Compiler::CONCURRENT
                                        : Compiler::NOT_CONCURRENT;
-  Handle<Code> result = Handle<Code>::null();
 
   OptimizedCompileJob* job = NULL;
   if (mode == Compiler::CONCURRENT) {
@@ -269,22 +268,24 @@ RUNTIME_FUNCTION(Runtime_CompileForOnStackReplacement) {
     job = dispatcher->FindReadyOSRCandidate(function, ast_id);
   }
 
+  MaybeHandle<Code> maybe_result;
   if (job != NULL) {
     if (FLAG_trace_osr) {
       PrintF("[OSR - Found ready: ");
       function->PrintName();
       PrintF(" at AST id %d]\n", ast_id.ToInt());
     }
-    result = Compiler::GetConcurrentlyOptimizedCode(job);
+    maybe_result = Compiler::GetConcurrentlyOptimizedCode(job);
   } else if (IsSuitableForOnStackReplacement(isolate, function)) {
     if (FLAG_trace_osr) {
       PrintF("[OSR - Compiling: ");
       function->PrintName();
       PrintF(" at AST id %d]\n", ast_id.ToInt());
     }
-    MaybeHandle<Code> maybe_result = Compiler::GetOptimizedCode(
+    maybe_result = Compiler::GetOptimizedCode(
         function, mode, ast_id,
         (mode == Compiler::NOT_CONCURRENT) ? frame : nullptr);
+    Handle<Code> result;
     if (maybe_result.ToHandle(&result) &&
         result.is_identical_to(isolate->builtins()->InOptimizationQueue())) {
       // Optimization is queued.  Return to check later.
@@ -296,7 +297,9 @@ RUNTIME_FUNCTION(Runtime_CompileForOnStackReplacement) {
   BackEdgeTable::Revert(isolate, *caller_code);
 
   // Check whether we ended up with usable optimized code.
-  if (!result.is_null() && result->kind() == Code::OPTIMIZED_FUNCTION) {
+  Handle<Code> result;
+  if (maybe_result.ToHandle(&result) &&
+      result->kind() == Code::OPTIMIZED_FUNCTION) {
     DeoptimizationInputData* data =
         DeoptimizationInputData::cast(result->deoptimization_data());