Don't emit code for instructions that are hiding behind an HSoftDeoptimize

src/x64/lithium-x64.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 75 matching lines @@
   V(CmpT)                                       \
   V(ConstantD)                                  \
   V(ConstantI)                                  \
   V(ConstantT)                                  \
   V(Context)                                    \
   V(DeclareGlobals)                             \
   V(DeleteProperty)                             \
   V(Deoptimize)                                 \
   V(DivI)                                       \
   V(DoubleToI)                                  \
+  V(DummyUse)                                   \
   V(ElementsKind)                               \
   V(FastLiteral)                                \
   V(FixedArrayBaseLength)                       \
   V(MapEnumLength)                              \
   V(FunctionLiteral)                            \
   V(GetCachedArrayIndex)                        \
   V(GlobalObject)                               \
   V(GlobalReceiver)                             \
   V(Goto)                                       \
   V(HasCachedArrayIndexAndBranch)               \
@@ skipping 291 matching lines @@
   void set_gap_instructions_size(int gap_instructions_size) {
     gap_instructions_size_ = gap_instructions_size;
   }
   int gap_instructions_size() { return gap_instructions_size_; }
 
  private:
   int gap_instructions_size_;
 };
 
 
+class LDummyUse: public LTemplateInstruction<1, 1, 0> {
+ public:
+  explicit LDummyUse(LOperand* value) {
+    inputs_[0] = value;
+  }
+  DECLARE_CONCRETE_INSTRUCTION(DummyUse, "dummy-use")
+};
+
+
 class LDeoptimize: public LTemplateInstruction<0, 0, 0> {
  public:
   DECLARE_CONCRETE_INSTRUCTION(Deoptimize, "deoptimize")
 };
 
 
 class LLabel: public LGap {
  public:
   explicit LLabel(HBasicBlock* block)
       : LGap(block), replacement_(NULL) { }
@@ skipping 2120 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_