Vendor things

third-party/vendor/psm/examples/thread.rs

@@ -0,0 +1,60 @@
+extern crate psm;
+
+psm::psm_stack_manipulation! {
+    yes {
+        use std::alloc;
+
+        const STACK_ALIGN: usize = 4096;
+        const FRAME_SIZE: usize = 4096;
+        const FIB_COUNTS: [(usize, u64); 3] = [
+            (8, 21),
+            (16, 987),
+            (24, 46368),
+        ];
+
+        #[inline(never)]
+        fn fib(n: usize) -> u64 {
+            unsafe {
+                let layout = alloc::Layout::from_size_align(FRAME_SIZE, STACK_ALIGN).unwrap();
+                let new_stack = alloc::alloc(layout);
+                assert!(!new_stack.is_null(), "allocations must succeed!");
+                let r = match n {
+                    0 => 0,
+                    1 => 1,
+                    _ => {
+                        psm::on_stack(new_stack, FRAME_SIZE, || {
+                            fib(n - 1) + fib(n - 2)
+                        })
+                    }
+                };
+                alloc::dealloc(new_stack, layout);
+                r
+            }
+        }
+
+        fn main() {
+            for (n, expected, handle) in FIB_COUNTS.iter().map(|&(n, expected)|
+                (n, expected, std::thread::spawn(move || {
+                    fib(n)
+                }))
+            ) {
+                if let Ok(res) = handle.join() {
+                    assert_eq!(res, expected);
+                    println!("fib({}) = {}", n, res);
+                } else {
+                    panic!("joining a thread returned an Err");
+                }
+            }
+        }
+    }
+    no {
+        fn main() {
+            eprintln!("Stack manipulation not supported by this target");
+        }
+    }
+}
+
+#[test]
+fn run_example() {
+    main()
+}