[turbofan] Proper dead code elimination as regular reducer.

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 385 matching lines @@
                               : builder_->environment()->Checkpoint(id_before);
   }
 
   void AddToNode(Node* node, BailoutId id_after,
                  OutputFrameStateCombine combine) {
     int count = OperatorProperties::GetFrameStateInputCount(node->op());
     DCHECK_LE(count, 2);
 
     if (count >= 1) {
       // Add the frame state for after the operation.
-      DCHECK_EQ(IrOpcode::kDeadValue,
+      DCHECK_EQ(IrOpcode::kDead,
                 NodeProperties::GetFrameStateInput(node, 0)->opcode());
 
       Node* frame_state_after =
           id_after == BailoutId::None()
               ? builder_->jsgraph()->EmptyFrameState()
               : builder_->environment()->Checkpoint(id_after, combine);
 
       NodeProperties::ReplaceFrameStateInput(node, 0, frame_state_after);
     }
 
     if (count >= 2) {
       // Add the frame state for before the operation.
-      DCHECK_EQ(IrOpcode::kDeadValue,
+      DCHECK_EQ(IrOpcode::kDead,
                 NodeProperties::GetFrameStateInput(node, 1)->opcode());
       NodeProperties::ReplaceFrameStateInput(node, 1, frame_state_before_);
     }
   }
 
  private:
   AstGraphBuilder* builder_;
   Node* frame_state_before_;
 };
 
@@ skipping 3324 matching lines @@
     return true;
   }
   return false;
 }
 
 
 void AstGraphBuilder::PrepareFrameState(Node* node, BailoutId ast_id,
                                         OutputFrameStateCombine combine) {
   if (OperatorProperties::GetFrameStateInputCount(node->op()) > 0) {
     DCHECK_EQ(1, OperatorProperties::GetFrameStateInputCount(node->op()));
-    DCHECK_EQ(IrOpcode::kDeadValue,
+
+    DCHECK_EQ(IrOpcode::kDead,
               NodeProperties::GetFrameStateInput(node, 0)->opcode());
     NodeProperties::ReplaceFrameStateInput(
         node, 0, environment()->Checkpoint(ast_id, combine));
   }
 }
 
 
 BitVector* AstGraphBuilder::GetVariablesAssignedInLoop(
     IterationStatement* stmt) {
   if (loop_assignment_analysis_ == NULL) return NULL;
@@ skipping 34 matching lines @@
     if (has_control) ++input_count_with_deps;
     if (has_effect) ++input_count_with_deps;
     Node** buffer = EnsureInputBufferSize(input_count_with_deps);
     memcpy(buffer, value_inputs, kPointerSize * value_input_count);
     Node** current_input = buffer + value_input_count;
     if (has_context) {
       *current_input++ = current_context();
     }
     for (int i = 0; i < frame_state_count; i++) {
       // The frame state will be inserted later. Here we misuse
-      // the {DeadValue} node as a sentinel to be later overwritten
+      // the {Dead} node as a sentinel to be later overwritten
       // with the real frame state.
-      *current_input++ = jsgraph()->DeadValue();
+      *current_input++ = jsgraph()->Dead();
     }
     if (has_effect) {
       *current_input++ = environment_->GetEffectDependency();
     }
     if (has_control) {
       *current_input++ = environment_->GetControlDependency();
     }
     result = graph()->NewNode(op, input_count_with_deps, buffer, incomplete);
     if (!environment()->IsMarkedAsUnreachable()) {
       // Update the current control dependency for control-producing nodes.
@@ skipping 246 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