Rollup merge of #74285 - wangtheo:issue-71669, r=lcnr

#71669: add ui, codegen tests for volatile + nearby int intrinsics

Added some tests for intrinsics. See https://github.com/rust-lang/rust/issues/71669.

src/test/ui/intrinsics/intrinsic-nearby.rs

@@ -0,0 +1,11 @@
+// run-pass
+#![feature(core_intrinsics)]
+
+use std::intrinsics::*;
+
+fn main() {
+    unsafe {
+        assert_eq!(nearbyintf32(5.234f32), 5f32);
+        assert_eq!(nearbyintf64(6.777f64), 7f64);
+    }
+}

src/test/ui/intrinsics/intrinsic-volatile.rs

@@ -0,0 +1,44 @@
+// run-pass
+
+#![feature(core_intrinsics)]
+
+use std::intrinsics::*;
+
+pub fn main() {
+    unsafe {
+        let mut x: Box<u8> = Box::new(0);
+        let mut y: Box<u8> = Box::new(0);
+
+        // test volatile load
+        assert_eq!(volatile_load(&*x), 0);
+        *x = 1;
+        assert_eq!(volatile_load(&*x), 1);
+
+        // test volatile store
+        volatile_store(&mut *x, 2);
+        assert_eq!(*x, 2);
+
+        // test volatile copy memory
+        volatile_copy_memory(&mut *y, &*x, 1);
+        assert_eq!(*y, 2);
+
+        // test volatile copy non-overlapping memory
+        *x = 3;
+        volatile_copy_nonoverlapping_memory(&mut *y, &*x, 1);
+        assert_eq!(*y, 3);
+
+        // test volatile set memory
+        volatile_set_memory(&mut *x, 4, 1);
+        assert_eq!(*x, 4);
+
+        // test unaligned volatile load
+        let arr: [u8; 3] = [1, 2, 3];
+        let ptr = arr[1..].as_ptr() as *const u16;
+        assert_eq!(unaligned_volatile_load(ptr), u16::from_ne_bytes([arr[1], arr[2]]));
+
+        // test unaligned volatile store
+        let ptr = arr[1..].as_ptr() as *mut u16;
+        unaligned_volatile_store(ptr, 0);
+        assert_eq!(arr, [1, 0, 0]);
+    }
+}