Added the bsf instruction to the disassembler of x64 and ia32.

src/x64/disasm-x64.cc

Index: src/x64/disasm-x64.cc
diff --git a/src/x64/disasm-x64.cc b/src/x64/disasm-x64.cc
index 3b2f6032743da654718f88cd48ab94f21ef5dd59..5dacdd7c3241f109c74e4d57bfe095d38fcf0fb6 100644
--- a/src/x64/disasm-x64.cc
+++ b/src/x64/disasm-x64.cc
@@ -1824,6 +1824,12 @@ int DisassemblerX64::TwoByteOpcodeInstruction(byte* data) {
     } else {
       AppendToBuffer(",%s,cl", NameOfCPURegister(regop));
     }
+  } else if (opcode == 0xBC) {
+    AppendToBuffer("%s%c ", mnemonic, operand_size_code());
+    int mod, regop, rm;
+    get_modrm(*current, &mod, &regop, &rm);
+    AppendToBuffer("%s,", NameOfCPURegister(regop));
+    current += PrintRightOperand(current);
   } else if (opcode == 0xBD) {
     AppendToBuffer("%s%c ", mnemonic, operand_size_code());
     int mod, regop, rm;
@@ -1878,6 +1884,8 @@ const char* DisassemblerX64::TwoByteMnemonic(byte opcode) {
       return "movzxb";
     case 0xB7:
       return "movzxw";
+    case 0xBC:
+      return "bsf";
     case 0xBD:
       return "bsr";
     case 0xBE: