Elide unnecessary context reload in generated stubs.

src/hydrogen.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3381 matching lines @@
   AddSimulate(BailoutId::Declarations());
 
   HValue* context = environment()->LookupContext();
   AddInstruction(
       new(zone()) HStackCheck(context, HStackCheck::kFunctionEntry));
 
   VisitStatements(info()->function()->body());
   if (HasStackOverflow()) return false;
 
   if (current_block() != NULL) {
-    HReturn* instr = new(zone()) HReturn(graph()->GetConstantUndefined());
+    HReturn* instr = new(zone()) HReturn(graph()->GetConstantUndefined(),
+                                         context);
     current_block()->FinishExit(instr);
     set_current_block(NULL);
   }
 
   // If the checksum of the number of type info changes is the same as the
   // last time this function was compiled, then this recompile is likely not
   // due to missing/inadequate type feedback, but rather too aggressive
   // optimization. Disable optimistic LICM in that case.
   Handle<Code> unoptimized_code(info()->shared_info()->code());
   ASSERT(unoptimized_code->kind() == Code::FUNCTION);
@@ skipping 795 matching lines @@
 void HOptimizedGraphBuilder::VisitReturnStatement(ReturnStatement* stmt) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   FunctionState* state = function_state();
   AstContext* context = call_context();
   if (context == NULL) {
     // Not an inlined return, so an actual one.
     CHECK_ALIVE(VisitForValue(stmt->expression()));
     HValue* result = environment()->Pop();
-    current_block()->FinishExit(new(zone()) HReturn(result));
+    current_block()->FinishExit(new(zone()) HReturn(
+        result,
+        environment()->LookupContext()));
   } else if (state->inlining_kind() == CONSTRUCT_CALL_RETURN) {
     // Return from an inlined construct call. In a test context the return value
     // will always evaluate to true, in a value context the return value needs
     // to be a JSObject.
     if (context->IsTest()) {
       TestContext* test = TestContext::cast(context);
       CHECK_ALIVE(VisitForEffect(stmt->expression()));
       current_block()->Goto(test->if_true(), state);
     } else if (context->IsEffect()) {
       CHECK_ALIVE(VisitForEffect(stmt->expression()));
@@ skipping 5965 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal