Added roundss to the disassembler of x64 and ia32.

src/ia32/disasm-ia32.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>
 
 #if V8_TARGET_ARCH_IA32
 
@@ skipping 1612 matching lines @@
                              NameOfXMMRegister(rm));
               data++;
             } else if (*data == 0x2A) {
               // movntdqa
               UnimplementedInstruction();
             } else {
               UnimplementedInstruction();
             }
           } else if (*data == 0x3A) {
             data++;
-            if (*data == 0x0B) {
+            if (*data == 0x0A) {
               data++;
               int mod, regop, rm;
               get_modrm(*data, &mod, &regop, &rm);
+              int8_t imm8 = static_cast<int8_t>(data[1]);
+              AppendToBuffer("roundss %s,%s,%d", NameOfXMMRegister(regop),
+                             NameOfXMMRegister(rm), static_cast<int>(imm8));
+              data += 2;
+            } else if (*data == 0x0B) {
+              data++;
+              int mod, regop, rm;
+              get_modrm(*data, &mod, &regop, &rm);
               int8_t imm8 = static_cast<int8_t>(data[1]);
               AppendToBuffer("roundsd %s,%s,%d",
                              NameOfXMMRegister(regop),
                              NameOfXMMRegister(rm),
                              static_cast<int>(imm8));
               data += 2;
             } else if (*data == 0x16) {
               data++;
               int mod, regop, rm;
               get_modrm(*data, &mod, &rm, &regop);
@@ skipping 606 matching lines @@
       fprintf(f, "  ");
     }
     fprintf(f, "  %s\n", buffer.start());
   }
 }
 
 
 }  // namespace disasm
 
 #endif  // V8_TARGET_ARCH_IA32