Fix disassembly of sar(_, imm8)

src/x87/disasm-x87.cc

 // Copyright 2011 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 <assert.h>
 #include <stdarg.h>
 #include <stdio.h>
 
 #include "src/v8.h"
 
@@ skipping 588 matching lines @@
       mnem = "sar";
       break;
     default:
       UnimplementedInstruction();
   }
   AppendToBuffer("%s ", mnem);
   int count = PrintRightOperand(data);
   if (op == 0xD1) {
     imm8 = 1;
   } else if (op == 0xC1) {
-    imm8 = *(data + 2);
+    imm8 = *(data + 1);
     count++;
   } else if (op == 0xD3) {
     // Shift/rotate by cl.
   }
   if (imm8 >= 0) {
     AppendToBuffer(",%d", imm8);
   } else {
     AppendToBuffer(",cl");
   }
   return 1 + count;
@@ skipping 1146 matching lines @@
       fprintf(f, "  ");
     }
     fprintf(f, "  %s\n", buffer.start());
   }
 }
 
 
 }  // namespace disasm
 
 #endif  // V8_TARGET_ARCH_X87