Revert of [turbofan] Implement rounding of floats on x64 and ia32 without sse4.1.

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 caf427143635b60d993616811dbf5d3f387f63ca..05b199d558df567d3fae301a15a84713d61313d6 100644
--- a/src/x64/disasm-x64.cc
+++ b/src/x64/disasm-x64.cc
@@ -991,11 +991,6 @@
         break;
       case 0x2c:
         AppendToBuffer("vcvttss2si%s %s,", vex_w() ? "q" : "",
-                       NameOfCPURegister(regop));
-        current += PrintRightXMMOperand(current);
-        break;
-      case 0x2d:
-        AppendToBuffer("vcvtss2si%s %s,", vex_w() ? "q" : "",
                        NameOfCPURegister(regop));
         current += PrintRightXMMOperand(current);
         break;
@@ -1716,14 +1711,6 @@
       AppendToBuffer("cvttss2si%c %s,",
           operand_size_code(), NameOfCPURegister(regop));
       current += PrintRightXMMOperand(current);
-    } else if (opcode == 0x2D) {
-      // CVTSS2SI:
-      // Convert with rounded scalar single-precision FP to dword integer.
-      int mod, regop, rm;
-      get_modrm(*current, &mod, &regop, &rm);
-      AppendToBuffer("cvtss2si%c %s,", operand_size_code(),
-                     NameOfCPURegister(regop));
-      current += PrintRightXMMOperand(current);
     } else if (opcode == 0x7E) {
       int mod, regop, rm;
       get_modrm(*current, &mod, &regop, &rm);
@@ -1884,27 +1871,6 @@
     current += PrintRightOperand(current);
   } else if (opcode == 0x0B) {
     AppendToBuffer("ud2");
-  } else if (opcode == 0xAE) {
-    byte modrm = *(data + 2);
-    int mod, regop, rm;
-    get_modrm(modrm, &mod, &regop, &rm);
-    regop &= 0x7;  // The REX.R bit does not affect the operation.
-    const char* mnem = NULL;
-    switch (regop) {
-      case 2:
-        mnem = "ldmxcsr";
-        break;
-      case 3:
-        mnem = "stmxcsr";
-        break;
-      default:
-        UnimplementedInstruction();
-        return 2;
-    }
-    DCHECK_NOT_NULL(mnem);
-    AppendToBuffer("%s ", mnem);
-    current +=
-        PrintRightOperandHelper(current, &DisassemblerX64::NameOfCPURegister);
   } else {
     UnimplementedInstruction();
   }