[turbofan] Add DebugBreak machine operator and support

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 <map>
 
 #include "src/compiler/common-operator.h"
@@ skipping 245 matching lines @@
   void VisitCall(Node* call, BasicBlock* handler = nullptr);
   void VisitDeoptimizeIf(Node* node);
   void VisitDeoptimizeUnless(Node* node);
   void VisitTailCall(Node* call);
   void VisitGoto(BasicBlock* target);
   void VisitBranch(Node* input, BasicBlock* tbranch, BasicBlock* fbranch);
   void VisitSwitch(Node* node, const SwitchInfo& sw);
   void VisitDeoptimize(DeoptimizeKind kind, Node* value);
   void VisitReturn(Node* ret);
   void VisitThrow(Node* value);
+  void VisitDebugBreak();
 
   void EmitPrepareArguments(ZoneVector<compiler::PushParameter>* arguments,
                             const CallDescriptor* descriptor, Node* node);
 
   // ===========================================================================
 
   Schedule* schedule() const { return schedule_; }
   Linkage* linkage() const { return linkage_; }
   InstructionSequence* sequence() const { return sequence_; }
   Zone* instruction_zone() const { return sequence()->zone(); }
@@ skipping 16 matching lines @@
   IntVector virtual_registers_;
   InstructionScheduler* scheduler_;
   Frame* frame_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SELECTOR_H_