[deoptimizer] Clear context before NotifyDeoptimized.

src/runtime/runtime-compiler.cc

Index: src/runtime/runtime-compiler.cc
diff --git a/src/runtime/runtime-compiler.cc b/src/runtime/runtime-compiler.cc
index b5910e4d3b25740cf4c7fcba957451731ca5cb4f..ab1f0547ee0557620a197f583e9f37ac8b3fd455 100644
--- a/src/runtime/runtime-compiler.cc
+++ b/src/runtime/runtime-compiler.cc
@@ -172,6 +172,17 @@ RUNTIME_FUNCTION(Runtime_NotifyDeoptimized) {
 
   DCHECK(optimized_code->kind() == Code::OPTIMIZED_FUNCTION);
   DCHECK(type == deoptimizer->bailout_type());
+  DCHECK(isolate->context() == nullptr);

[Benedikt Meurer, 2016/09/07 16:58:00]

Nit: DCHECK_NULL

[Michael Starzinger, 2016/09/08 08:46:41]

Done.

+
+  // TODO(turbofan): For Crankshaft we restore the context before objects are
+  // being materialized, because it never de-materializes the context but it
+  // requires a context to materialize arguments objects. This is specific to
+  // Crankshaft and can be removed once only TurboFan goes through here.
+  if (!optimized_code->is_turbofanned()) {
+    JavaScriptFrameIterator top_it(isolate);
+    JavaScriptFrame* top_frame = top_it.frame();
+    isolate->set_context(Context::cast(top_frame->context()));
+  }
 
   // Make sure to materialize objects before causing any allocation.
   JavaScriptFrameIterator it(isolate);
@@ -179,9 +190,11 @@ RUNTIME_FUNCTION(Runtime_NotifyDeoptimized) {
   delete deoptimizer;
 
   // Ensure the context register is updated for materialized objects.
-  JavaScriptFrameIterator top_it(isolate);
-  JavaScriptFrame* top_frame = top_it.frame();
-  isolate->set_context(Context::cast(top_frame->context()));
+  if (optimized_code->is_turbofanned()) {
+    JavaScriptFrameIterator top_it(isolate);
+    JavaScriptFrame* top_frame = top_it.frame();
+    isolate->set_context(Context::cast(top_frame->context()));
+  }
 
   if (type == Deoptimizer::LAZY) {
     return isolate->heap()->undefined_value();