def VR256X : RegisterClass<"X86", [v32i8, v16i16, v8i32, v4i64, v8f32, v4f64],
256, (sequence "YMM%u", 0, 31)>;
-def VK8 : RegisterClass<"X86", [v8i1], 8, (sequence "K%u", 0, 7)>;
-def VK16 : RegisterClass<"X86", [v16i1], 16, (add VK8)>;
-
-def VK8WM : RegisterClass<"X86", [v8i1], 8, (sub VK8, K0)>;
+// The size of the all masked registers is 16 bit because we have only one
+// KMOVW istruction that can store this register in memory, and it writes 2 bytes
+def VK1 : RegisterClass<"X86", [i1], 16, (sequence "K%u", 0, 7)>;
+def VK8 : RegisterClass<"X86", [v8i1], 16, (add VK1)> {let Size = 16;}
+def VK16 : RegisterClass<"X86", [v16i1], 16, (add VK8)> {let Size = 16;}
+
+def VK1WM : RegisterClass<"X86", [i1], 16, (sub VK1, K0)> {let Size = 16;}
+def VK8WM : RegisterClass<"X86", [v8i1], 16, (sub VK8, K0)> {let Size = 16;}
def VK16WM : RegisterClass<"X86", [v16i1], 16, (add VK8WM)>;