[turbofan] Use OSR value for innermost context value.

src/compiler/ast-graph-builder.cc

 // Copyright 2014 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/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 480 matching lines @@
 
 
 Node* AstGraphBuilder::NewOuterContextParam() {
   // Parameter (arity + 1) is special for the outer context of the function
   const Operator* op =
       common()->Parameter(info()->num_parameters_including_this(), "%context");
   return NewNode(op, graph()->start());
 }
 
 
-Node* AstGraphBuilder::NewCurrentContextOsrValue() {
-  // TODO(titzer): use a real OSR value here; a parameter works by accident.
-  // Parameter (arity + 1) is special for the outer context of the function
-  const Operator* op = common()->Parameter(
-      info()->num_parameters_including_this(), "%osr-context");
-  return NewNode(op, graph()->start());
-}
-
-
 bool AstGraphBuilder::CreateGraph(bool constant_context, bool stack_check) {
   Scope* scope = info()->scope();
   DCHECK(graph() != NULL);
 
   // Set up the basic structure of the graph.
   int parameter_count = info()->num_parameters();
   graph()->SetStart(graph()->NewNode(common()->Start(parameter_count)));
 
   // Initialize the top-level environment.
   Environment env(this, scope, graph()->start());
@@ skipping 3566 matching lines @@
         values()->at(i) = builder_->MergeValue(val, osr_value, control);
       }
     }
 
     // Rename all the contexts in the environment.
     // The innermost context is the OSR value, and the outer contexts are
     // reconstructed by dynamically walking up the context chain.
     Node* osr_context = nullptr;
     const Operator* op =
         builder_->javascript()->LoadContext(0, Context::PREVIOUS_INDEX, true);
+    const Operator* op_inner =
+        builder_->common()->OsrValue(Linkage::kOsrContextSpillSlotIndex);
     int last = static_cast<int>(contexts()->size() - 1);
     for (int i = last; i >= 0; i--) {
       Node* val = contexts()->at(i);
       if (!IrOpcode::IsConstantOpcode(val->opcode())) {
-        osr_context = (i == last) ? builder_->NewCurrentContextOsrValue()
+        osr_context = (i == last) ? graph->NewNode(op_inner, osr_loop_entry)
                                   : graph->NewNode(op, osr_context, osr_context,
                                                    osr_loop_entry);
         contexts()->at(i) = builder_->MergeValue(val, osr_context, control);
       } else {
         osr_context = val;
       }
     }
   }
 }
 
@@ skipping 66 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8