[interpreter] Workaround for unused frame states.

src/compiler/bytecode-graph-builder.cc

 // Copyright 2015 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/bytecode-graph-builder.h"
 
 #include "src/compiler/bytecode-branch-analysis.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/operator-properties.h"
 #include "src/interpreter/bytecodes.h"
@@ skipping 83 matching lines @@
   int accumulator_base_;
 };
 
 // Helper for generating frame states for before and after a bytecode.
 class BytecodeGraphBuilder::FrameStateBeforeAndAfter {
  public:
   explicit FrameStateBeforeAndAfter(BytecodeGraphBuilder* builder)
       : builder_(builder),
         id_after_(BailoutId::None()),
         added_to_node_(false),
+        frame_states_unused_(false),
         output_poke_offset_(0),
         output_poke_count_(0) {
     BailoutId id_before(builder->bytecode_iterator().current_offset());
     frame_state_before_ = builder_->environment()->Checkpoint(
         id_before, OutputFrameStateCombine::Ignore());
     id_after_ = BailoutId(id_before.ToInt() +
                           builder->bytecode_iterator().current_bytecode_size());
   }
 
   ~FrameStateBeforeAndAfter() {
     DCHECK(added_to_node_);
-    DCHECK(builder_->environment()->StateValuesAreUpToDate(output_poke_offset_,
+    DCHECK(frame_states_unused_ ||
+           builder_->environment()->StateValuesAreUpToDate(output_poke_offset_,
                                                            output_poke_count_));
   }
 
  private:
   friend class Environment;
 
   void AddToNode(Node* node, OutputFrameStateCombine combine) {
     DCHECK(!added_to_node_);
     int count = OperatorProperties::GetFrameStateInputCount(node->op());
     DCHECK_LE(count, 2);
@@ skipping 10 matching lines @@
       // Add the frame state for before the operation.
       DCHECK_EQ(IrOpcode::kDead,
                 NodeProperties::GetFrameStateInput(node, 1)->opcode());
       NodeProperties::ReplaceFrameStateInput(node, 1, frame_state_before_);
     }
 
     if (!combine.IsOutputIgnored()) {
       output_poke_offset_ = static_cast<int>(combine.GetOffsetToPokeAt());
       output_poke_count_ = node->op()->ValueOutputCount();
     }
+    frame_states_unused_ = count == 0;
     added_to_node_ = true;
   }
 
   BytecodeGraphBuilder* builder_;
   Node* frame_state_before_;
   BailoutId id_after_;
 
   bool added_to_node_;
+  bool frame_states_unused_;
   int output_poke_offset_;
   int output_poke_count_;
 };
 
 
 // Issues:
 // - Scopes - intimately tied to AST. Need to eval what is needed.
 // - Need to resolve closure parameter treatment.
 BytecodeGraphBuilder::Environment::Environment(BytecodeGraphBuilder* builder,
                                                int register_count,
@@ skipping 1668 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