ARM64 simulator fix for EXTR

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 2085 matching lines @@
   result = signbits | (result & mask) | (dst & ~mask);
 
   set_reg(reg_size, instr->Rd(), result);
 }
 
 
 void Simulator::VisitExtract(Instruction* instr) {
   unsigned lsb = instr->ImmS();
   unsigned reg_size = (instr->SixtyFourBits() == 1) ? kXRegSizeInBits
                                                     : kWRegSizeInBits;
-  set_reg(reg_size,
-          instr->Rd(),
-          (static_cast<uint64_t>(reg(reg_size, instr->Rm())) >> lsb) |
-          (reg(reg_size, instr->Rn()) << (reg_size - lsb)));
+  uint64_t result = reg(reg_size, instr->Rm());
+  if (lsb) {
+    result = (result >> lsb) | (reg(reg_size, instr->Rn()) << (reg_size - lsb));
+  }
+
+  set_reg(reg_size, instr->Rd(), result);
 }
 
 
 void Simulator::VisitFPImmediate(Instruction* instr) {
   AssertSupportedFPCR();
 
   unsigned dest = instr->Rd();
   switch (instr->Mask(FPImmediateMask)) {
     case FMOV_s_imm: set_sreg(dest, instr->ImmFP32()); break;
     case FMOV_d_imm: set_dreg(dest, instr->ImmFP64()); break;
@@ skipping 1604 matching lines @@
 
   delete[] format;
 }
 
 
 #endif  // USE_SIMULATOR
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64