add macros to validate imm2, imm3, and imm4

Author: lqd

crates/core_arch/src/macros.rs

@@ -1,8 +1,8 @@
 //! Utility macros.
 
 // Helper struct used to trigger const eval errors when a const generic immediate value is
-// out of range.
-pub(crate) struct ValidateConstImm8<const imm8: i32>();
+// out of 8-bit range.
+pub(crate) struct ValidateConstImm8<const imm8: i32>;
 impl<const imm8: i32> ValidateConstImm8<imm8> {
     pub(crate) const VALID: () = {
         let _ = 1 / ((imm8 >= 0 && imm8 <= 255) as usize);

crates/core_arch/src/x86/macros.rs

@@ -1,5 +1,51 @@
 //! Utility macros.
+// Helper struct used to trigger const eval errors when a const generic immediate value is
+// out of 2-bit range.
+pub(crate) struct ValidateConstImm2<const imm2: i32>;
+impl<const imm2: i32> ValidateConstImm2<imm2> {
+    pub(crate) const VALID: () = {
+        let _ = 1 / ((imm2 >= 0 && imm2 <= 3) as usize);
+    };
+}
+
+#[allow(unused)]
+macro_rules! static_assert_imm2 {
+    ($imm:ident) => {
+        let _ = $crate::core_arch::x86::macros::ValidateConstImm2::<$imm>::VALID;
+    };
+}
 
+// Helper struct used to trigger const eval errors when a const generic immediate value is
+// out of 3-bit range.
+pub(crate) struct ValidateConstImm3<const imm3: i32>;
+impl<const imm3: i32> ValidateConstImm3<imm3> {
+    pub(crate) const VALID: () = {
+        let _ = 1 / ((imm3 >= 0 && imm3 <= 7) as usize);
+    };
+}
+
+#[allow(unused)]
+macro_rules! static_assert_imm3 {
+    ($imm:ident) => {
+        let _ = $crate::core_arch::x86::macros::ValidateConstImm3::<$imm>::VALID;
+    };
+}
+
+// Helper struct used to trigger const eval errors when a const generic immediate value is
+// out of 4-bit range.
+pub(crate) struct ValidateConstImm4<const imm4: i32>;
+impl<const imm4: i32> ValidateConstImm4<imm4> {
+    pub(crate) const VALID: () = {
+        let _ = 1 / ((imm4 >= 0 && imm4 <= 15) as usize);
+    };
+}
+
+#[allow(unused)]
+macro_rules! static_assert_imm4 {
+    ($imm:ident) => {
+        let _ = $crate::core_arch::x86::macros::ValidateConstImm4::<$imm>::VALID;
+    };
+}
 macro_rules! constify_imm6 {
     ($imm8:expr, $expand:ident) => {
         #[allow(overflowing_literals)]