require naked functions to be unsafe again

they dereference raw pointers, so the caller needs to make sure the
pointer is valid.

note that this requires changing `maybe_use_optimized_c_shim` to support
unsafe functions.

Author: jyn514

src/aarch64.rs

@@ -131,7 +131,7 @@ macro_rules! compare_and_swap {
         intrinsics! {
             #[maybe_use_optimized_c_shim]
             #[naked]
-            pub extern "C" fn $name (
+            pub unsafe extern "C" fn $name (
                 expected: int_ty!($bytes), desired: int_ty!($bytes), ptr: *mut int_ty!($bytes)
             ) -> int_ty!($bytes) {
                 // We can't use `AtomicI8::compare_and_swap`; we *are* compare_and_swap.
@@ -162,7 +162,7 @@ macro_rules! compare_and_swap_i128 {
         intrinsics! {
             #[maybe_use_optimized_c_shim]
             #[naked]
-            pub extern "C" fn $name (
+            pub unsafe extern "C" fn $name (
                 expected: i128, desired: i128, ptr: *mut i128
             ) -> i128 {
                 unsafe { core::arch::asm! {
@@ -192,7 +192,7 @@ macro_rules! swap {
         intrinsics! {
             #[maybe_use_optimized_c_shim]
             #[naked]
-            pub extern "C" fn $name (
+            pub unsafe extern "C" fn $name (
                 left: int_ty!($bytes), right_ptr: *mut int_ty!($bytes)
             ) -> int_ty!($bytes) {
                 unsafe { core::arch::asm! {
@@ -218,7 +218,7 @@ macro_rules! fetch_op {
         intrinsics! {
             #[maybe_use_optimized_c_shim]
             #[naked]
-            pub extern "C" fn $name (
+            pub unsafe extern "C" fn $name (
                 val: int_ty!($bytes), ptr: *mut int_ty!($bytes)
             ) -> int_ty!($bytes) {
                 unsafe { core::arch::asm! {

src/macros.rs

@@ -204,15 +204,15 @@ macro_rules! intrinsics {
     (
         #[maybe_use_optimized_c_shim]
         $(#[$($attr:tt)*])*
-        pub extern $abi:tt fn $name:ident( $($argname:ident:  $ty:ty),* ) $(-> $ret:ty)? {
+        pub $(unsafe $(@ $empty:tt)? )? extern $abi:tt fn $name:ident( $($argname:ident:  $ty:ty),* ) $(-> $ret:ty)? {
             $($body:tt)*
         }
 
         $($rest:tt)*
     ) => (
         #[cfg($name = "optimized-c")]
         #[cfg_attr(feature = "weak-intrinsics", linkage = "weak")]
-        pub extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
+        pub $(unsafe $($empty)? )? extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
             extern $abi {
                 fn $name($($argname: $ty),*) $(-> $ret)?;
             }
@@ -224,7 +224,7 @@ macro_rules! intrinsics {
         #[cfg(not($name = "optimized-c"))]
         intrinsics! {
             $(#[$($attr)*])*
-            pub extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
+            pub $(unsafe $($empty)? )? extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
                 $($body)*
             }
         }
@@ -419,7 +419,7 @@ macro_rules! intrinsics {
     (
         #[naked]
         $(#[$($attr:tt)*])*
-        pub $(unsafe)? extern $abi:tt fn $name:ident( $($argname:ident:  $ty:ty),* ) $(-> $ret:ty)? {
+        pub unsafe extern $abi:tt fn $name:ident( $($argname:ident:  $ty:ty),* ) $(-> $ret:ty)? {
             $($body:tt)*
         }