s390: introduce DUMY opcode for special use.

src/s390/constants-s390.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_S390_CONSTANTS_S390_H_
 #define V8_S390_CONSTANTS_S390_H_
 
 // Get the standard printf format macros for C99 stdint types.
 #ifndef __STDC_FORMAT_MACROS
 #define __STDC_FORMAT_MACROS
@@ skipping 897 matching lines @@
   XGRK = 0xB9E7,      // Exclusive Or (64)
   XI = 0x97,          // Exclusive Or (immediate)
   XIHF = 0xC06,       // Exclusive Or Immediate (high)
   XILF = 0xC07,       // Exclusive Or Immediate (low)
   XIY = 0xEB57,       // Exclusive Or (immediate)
   XR = 0x17,          // Exclusive Or (32)
   XRK = 0xB9F7,       // Exclusive Or (32)
   XSCH = 0xB276,      // Cancel Subchannel
   XY = 0xE357,        // Exclusive Or (32)
   ZAP = 0xF8,         // Zero And Add
-  BKPT = 0x0001       // GDB Software Breakpoint
+  BKPT = 0x0001,      // GDB Software Breakpoint
+  DUMY = 0xE353       // Special dummy opcode
 };
 
 // Instruction encoding bits and masks.
 enum {
   // Instruction encoding bit
   B1 = 1 << 1,
   B4 = 1 << 4,
   B5 = 1 << 5,
   B7 = 1 << 7,
   B8 = 1 << 8,
@@ skipping 593 matching lines @@
   static int Number(const char* name);
 
  private:
   static const char* names_[kNumDoubleRegisters];
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_S390_CONSTANTS_S390_H_