Implemented the RoundInt64ToFloat32 TurboFan operator for x64, arm64, and mips64.

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 966 matching lines @@
         current += PrintRightXMMOperand(current);
         break;
       case 0x11:
         AppendToBuffer("vmovss ");
         current += PrintRightXMMOperand(current);
         if (mod == 3) {
           AppendToBuffer(",%s", NameOfXMMRegister(vvvv));
         }
         AppendToBuffer(",%s", NameOfXMMRegister(regop));
         break;
+      case 0x2a:
+        AppendToBuffer("%s %s,%s,", vex_w() ? "vcvtqsi2ss" : "vcvtlsi2ss",
+                       NameOfXMMRegister(regop), NameOfXMMRegister(vvvv));
+        current += PrintRightOperand(current);
+        break;
       case 0x58:
         AppendToBuffer("vaddss %s,%s,", NameOfXMMRegister(regop),
                        NameOfXMMRegister(vvvv));
         current += PrintRightXMMOperand(current);
         break;
       case 0x59:
         AppendToBuffer("vmulss %s,%s,", NameOfXMMRegister(regop),
                        NameOfXMMRegister(vvvv));
         current += PrintRightXMMOperand(current);
         break;
@@ skipping 1488 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