Port CompileMathFloorCall from ia32 to x64

src/x64/disasm-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1135 matching lines @@
       get_modrm(*current, &mod, &regop, &rm);
       AppendToBuffer("cvtsd2si%c %s,",
           operand_size_code(), NameOfCPURegister(regop));
       current += PrintRightXMMOperand(current);
     } else if ((opcode & 0xF8) == 0x58 || opcode == 0x51) {
       // XMM arithmetic. Mnemonic was retrieved at the start of this function.
       int mod, regop, rm;
       get_modrm(*current, &mod, &regop, &rm);
       AppendToBuffer("%s %s,", mnemonic, NameOfXMMRegister(regop));
       current += PrintRightXMMOperand(current);
+    } else if (opcode == 0xC2) {
+      // Intel manual 2A, Table 3-18.
+      int mod, regop, rm;
+      get_modrm(*current, &mod, &regop, &rm);
+      const char* const pseudo_op[] = {
+        "cmpeqsd",
+        "cmpltsd",
+        "cmplesd",
+        "cmpunordsd",
+        "cmpneqsd",
+        "cmpnltsd",
+        "cmpnlesd",
+        "cmpordsd"
+      };
+      AppendToBuffer("%s %s,%s",
+                     pseudo_op[current[1]],
+                     NameOfXMMRegister(regop),
+                     NameOfXMMRegister(rm));
+      current += 2;
     } else {
       UnimplementedInstruction();
     }
   } else if (group_1_prefix_ == 0xF3) {
     // Instructions with prefix 0xF3.
     if (opcode == 0x11 || opcode == 0x10) {
       // MOVSS: Move scalar double-precision fp to/from/between XMM registers.
       AppendToBuffer("movss ");
       int mod, regop, rm;
       get_modrm(*current, &mod, &regop, &rm);
@@ skipping 699 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