Added roundss to the disassembler of x64 and ia32.

src/x64/disasm-x64.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_X64
 
@@ skipping 938 matching lines @@
         current += PrintRightOperand(current);
         AppendToBuffer(",%s", NameOfCPURegister(vvvv));
         break;
       default:
         UnimplementedInstruction();
     }
   } else if (vex_66() && vex_0f3a()) {
     int mod, regop, rm, vvvv = vex_vreg();
     get_modrm(*current, &mod, &regop, &rm);
     switch (opcode) {
+      case 0x0a:
+        AppendToBuffer("vroundss %s,%s,", NameOfXMMRegister(regop),
+                       NameOfXMMRegister(vvvv));
+        current += PrintRightXMMOperand(current);
+        AppendToBuffer(",0x%x", *current++);
+        break;
       case 0x0b:
         AppendToBuffer("vroundsd %s,%s,", NameOfXMMRegister(regop),
                        NameOfXMMRegister(vvvv));
         current += PrintRightXMMOperand(current);
         AppendToBuffer(",0x%x", *current++);
         break;
       default:
         UnimplementedInstruction();
     }
   } else if (vex_f3() && vex_0f()) {
@@ skipping 540 matching lines @@
     int mod, regop, rm;
     if (opcode == 0x3A) {
       byte third_byte = *current;
       current = data + 3;
       if (third_byte == 0x17) {
         get_modrm(*current, &mod, &regop, &rm);
         AppendToBuffer("extractps ");  // reg/m32, xmm, imm8
         current += PrintRightOperand(current);
         AppendToBuffer(",%s,%d", NameOfXMMRegister(regop), (*current) & 3);
         current += 1;
+      } else if (third_byte == 0x0a) {
+        get_modrm(*current, &mod, &regop, &rm);
+        AppendToBuffer("roundss %s,", NameOfXMMRegister(regop));
+        current += PrintRightXMMOperand(current);
+        AppendToBuffer(",0x%x", (*current) & 3);
+        current += 1;
       } else if (third_byte == 0x0b) {
         get_modrm(*current, &mod, &regop, &rm);
          // roundsd xmm, xmm/m64, imm8
         AppendToBuffer("roundsd %s,", NameOfXMMRegister(regop));
         current += PrintRightXMMOperand(current);
         AppendToBuffer(",0x%x", (*current) & 3);
         current += 1;
       } else if (third_byte == 0x16) {
         get_modrm(*current, &mod, &rm, &regop);
         AppendToBuffer("pextrd ");  // reg/m32, xmm, imm8
@@ skipping 961 matching lines @@
     for (int i = 6 - static_cast<int>(pc - prev_pc); i >= 0; i--) {
       fprintf(f, "  ");
     }
     fprintf(f, "  %s\n", buffer.start());
   }
 }
 
 }  // namespace disasm
 
 #endif  // V8_TARGET_ARCH_X64