[turbofan] Improve code generation for inline comparisons with zero.

src/compiler/instruction-selector.h

 // 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.
 
 #ifndef V8_COMPILER_INSTRUCTION_SELECTOR_H_
 #define V8_COMPILER_INSTRUCTION_SELECTOR_H_
 
 #include <deque>
 
 #include "src/compiler/common-operator.h"
@@ skipping 67 matching lines @@
 
   bool IsSupported(CpuFeature feature) const {
     return features_.Contains(feature);
   }
 
   // Returns the features supported on the target platform.
   static Features SupportedFeatures() {
     return Features(CpuFeatures::SupportedFeatures());
   }
 
-  // Checks if {node} is currently live.
-  bool IsLive(Node* node) const { return !IsDefined(node) && IsUsed(node); }
-
- private:
-  friend class OperandGenerator;
-
   // ===========================================================================
   // ============ Architecture-independent graph covering methods. =============
   // ===========================================================================
 
-  // Checks if {block} will appear directly after {current_block_} when
-  // assembling code, in which case, a fall-through can be used.
-  bool IsNextInAssemblyOrder(const BasicBlock* block) const;
-
   // Used in pattern matching during code generation.
   // Check if {node} can be covered while generating code for the current
   // instruction. A node can be covered if the {user} of the node has the only
   // edge and the two are in the same basic block.
   bool CanCover(Node* user, Node* node) const;
 
   // Checks if {node} was already defined, and therefore code was already
   // generated for it.
   bool IsDefined(Node* node) const;
 
-  // Inform the instruction selection that {node} was just defined.
-  void MarkAsDefined(Node* node);
-
   // Checks if {node} has any uses, and therefore code has to be generated for
   // it.
   bool IsUsed(Node* node) const;
 
+  // Checks if {node} is currently live.
+  bool IsLive(Node* node) const { return !IsDefined(node) && IsUsed(node); }
+
+ private:
+  friend class OperandGenerator;
+
+  // Checks if {block} will appear directly after {current_block_} when
+  // assembling code, in which case, a fall-through can be used.
+  bool IsNextInAssemblyOrder(const BasicBlock* block) const;
+
+  // Inform the instruction selection that {node} was just defined.
+  void MarkAsDefined(Node* node);
+
   // Inform the instruction selection that {node} has at least one use and we
   // will need to generate code for it.
   void MarkAsUsed(Node* node);
 
   // Checks if {node} is marked as double.
   bool IsDouble(const Node* node) const;
 
   // Inform the register allocator of a double result.
   void MarkAsDouble(Node* node);
 
@@ skipping 73 matching lines @@
   ZoneDeque<Instruction*> instructions_;
   BoolVector defined_;
   BoolVector used_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SELECTOR_H_