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

src/ia32/disasm-ia32.cc

Index: src/ia32/disasm-ia32.cc
diff --git a/src/ia32/disasm-ia32.cc b/src/ia32/disasm-ia32.cc
index 86de7ee439f3845e90f78d05904c8b296b8996c8..5a432806592f7c03903e66c99e629d8f87ab70f7 100644
--- a/src/ia32/disasm-ia32.cc
+++ b/src/ia32/disasm-ia32.cc
@@ -1484,29 +1484,6 @@
             } else {
               AppendToBuffer(",%s,cl", NameOfCPURegister(regop));
             }
-          } else if (f0byte == 0xAE) {
-            // ldmxcsr and stmxcsr
-            data += 2;
-            byte modrm = *data;
-            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);
-            data += PrintRightOperandHelper(
-                data, &DisassemblerIA32::NameOfCPURegister);
           } else if (f0byte == 0xBC) {
             data += 2;
             int mod, regop, rm;
@@ -1653,15 +1630,7 @@
             }
           } else if (*data == 0x3A) {
             data++;
-            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) {
+            if (*data == 0x0B) {
               data++;
               int mod, regop, rm;
               get_modrm(*data, &mod, &regop, &rm);