ARM64: Use the shifter operand to merge in previous shift instructions.

src/arm64/simulator-arm64.cc

 // Copyright 2013 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.
 
 #include <stdlib.h>
 #include <cmath>
 #include <cstdarg>
 #include "v8.h"
 
 #if V8_TARGET_ARCH_ARM64
@@ skipping 1961 matching lines @@
     case RORV_w:
     case RORV_x: shift_op = ROR; break;
     default: UNIMPLEMENTED();
   }
 
   unsigned reg_size = instr->SixtyFourBits() ? kXRegSizeInBits
                                              : kWRegSizeInBits;
   if (shift_op != NO_SHIFT) {
     // Shift distance encoded in the least-significant five/six bits of the
     // register.
-    int mask = (instr->SixtyFourBits() == 1) ? 0x3f : 0x1f;
+    int mask = (instr->SixtyFourBits() == 1) ? kShiftAmountXRegMask
+                                             : kShiftAmountWRegMask;
     unsigned shift = wreg(instr->Rm()) & mask;
     result = ShiftOperand(reg_size, reg(reg_size, instr->Rn()), shift_op,
                           shift);
   }
   set_reg(reg_size, instr->Rd(), result);
 }
 
 
 // The algorithm used is described in section 8.2 of
 //   Hacker's Delight, by Henry S. Warren, Jr.
@@ skipping 1639 matching lines @@
     default:
       UNIMPLEMENTED();
   }
 }
 
 #endif  // USE_SIMULATOR
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64