[turbofan] Support for combining branches with <Operation>WithOverflow.

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 53 matching lines @@
   // 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;
 
   // 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;
@@ skipping 32 matching lines @@
   // code if necessary.
   void VisitControl(BasicBlock* block);
 
   // Visit the node and generate code, if any.
   void VisitNode(Node* node);
 
 #define DECLARE_GENERATOR(x) void Visit##x(Node* node);
   MACHINE_OP_LIST(DECLARE_GENERATOR)
 #undef DECLARE_GENERATOR
 
+  void VisitInt32AddWithOverflow(Node* node, FlagsContinuation* cont);
+  void VisitInt32SubWithOverflow(Node* node, FlagsContinuation* cont);
+
   void VisitWord32Test(Node* node, FlagsContinuation* cont);
   void VisitWord64Test(Node* node, FlagsContinuation* cont);
   void VisitWord32Compare(Node* node, FlagsContinuation* cont);
   void VisitWord64Compare(Node* node, FlagsContinuation* cont);
   void VisitFloat64Compare(Node* node, FlagsContinuation* cont);
 
   void VisitParameter(Node* node);
   void VisitPhi(Node* node);
   void VisitProjection(Node* node);
   void VisitConstant(Node* node);
@@ skipping 17 matching lines @@
   // ===========================================================================
 
   typedef zone_allocator<Instruction*> InstructionPtrZoneAllocator;
   typedef std::deque<Instruction*, InstructionPtrZoneAllocator> Instructions;
 
   Zone zone_;
   InstructionSequence* sequence_;
   SourcePositionTable* source_positions_;
   BasicBlock* current_block_;
   Instructions instructions_;
+  BoolVector defined_;
   BoolVector used_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SELECTOR_H_