add ACLE random number generation intrinsics

Author: folkertdev

crates/core_arch/src/aarch64/mod.rs

@@ -17,6 +17,10 @@ mod mte;
 #[unstable(feature = "stdarch_aarch64_mte", issue = "129010")]
 pub use self::mte::*;
 
+mod rand;
+#[unstable(feature = "stdarch_aarch64_rand", issue = "153514")]
+pub use self::rand::*;
+
 mod neon;
 #[stable(feature = "neon_intrinsics", since = "1.59.0")]
 pub use self::neon::*;

crates/core_arch/src/aarch64/rand.rs

@@ -0,0 +1,69 @@
+//! AArch64 Random Number intrinsics
+//!
+//! [ACLE documentation](https://arm-software.github.io/acle/main/acle.html#random-number-generation-intrinsics)
+
+unsafe extern "unadjusted" {
+    #[cfg_attr(
+        any(target_arch = "aarch64", target_arch = "arm64ec"),
+        link_name = "llvm.aarch64.rndr"
+    )]
+    fn rndr_() -> PackedTuple<u64, bool>;
+
+    #[cfg_attr(
+        any(target_arch = "aarch64", target_arch = "arm64ec"),
+        link_name = "llvm.aarch64.rndrrs"
+    )]
+    fn rndrrs_() -> PackedTuple<u64, bool>;
+}
+
+#[repr(C)]
+struct PackedTuple<T, U> {
+    x: T,
+    y: U,
+}
+
+/// Stores a 64-bit random number into the object pointed to by the argument and returns
+/// zero. If the implementation could not generate a random number within a reasonable
+/// period of time the object pointed to by the input is set to zero and a non-zero value
+/// is returned.
+#[inline]
+#[target_feature(enable = "rand")]
+#[unstable(feature = "stdarch_aarch64_rand", issue = "153514")]
+pub unsafe fn __rndr(value: *mut u64) -> i32 {
+    let PackedTuple { x: bits, y: ok } = rndr_();
+    unsafe { *value = bits };
+    ok as i32
+}
+
+/// Reseeds the random number generator. After that stores a 64-bit random number into
+/// the object pointed to by the argument and returns zero. If the implementation could
+/// not generate a random number within a reasonable period of time the object pointed
+/// to by the input is set to zero and a non-zero value is returned.
+#[inline]
+#[target_feature(enable = "rand")]
+#[unstable(feature = "stdarch_aarch64_rand", issue = "153514")]
+pub unsafe fn __rndrrs(value: *mut u64) -> i32 {
+    let PackedTuple { x: bits, y: ok } = rndrrs_();
+    unsafe { *value = bits };
+    ok as i32
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use stdarch_test::assert_instr;
+
+    #[cfg_attr(test, assert_instr(mrs))]
+    #[allow(dead_code)]
+    #[target_feature(enable = "rand")]
+    unsafe fn test_rndr(value: &mut u64) -> i32 {
+        __rndr(value)
+    }
+
+    #[cfg_attr(test, assert_instr(mrs))]
+    #[allow(dead_code)]
+    #[target_feature(enable = "rand")]
+    unsafe fn test_rndrrs(value: &mut u64) -> i32 {
+        __rndrrs(value)
+    }
+}