Add 'library/portable-simd/' from commit '1ce1c645cf27c4acdefe6ec8a11d1f0491954a99'

git-subtree-dir: library/portable-simd
git-subtree-mainline: efd0483949
git-subtree-split: 1ce1c645cf

library/portable-simd/crates/test_helpers/src/array.rs

@@ -0,0 +1,97 @@
+//! Generic-length array strategy.
+
+// Adapted from proptest's array code
+// Copyright 2017 Jason Lingle
+
+use core::{marker::PhantomData, mem::MaybeUninit};
+use proptest::{
+    strategy::{NewTree, Strategy, ValueTree},
+    test_runner::TestRunner,
+};
+
+#[must_use = "strategies do nothing unless used"]
+#[derive(Clone, Copy, Debug)]
+pub struct UniformArrayStrategy<S, T> {
+    strategy: S,
+    _marker: PhantomData<T>,
+}
+
+impl<S, T> UniformArrayStrategy<S, T> {
+    pub const fn new(strategy: S) -> Self {
+        Self {
+            strategy,
+            _marker: PhantomData,
+        }
+    }
+}
+
+pub struct ArrayValueTree<T> {
+    tree: T,
+    shrinker: usize,
+    last_shrinker: Option<usize>,
+}
+
+impl<T, S, const LANES: usize> Strategy for UniformArrayStrategy<S, [T; LANES]>
+where
+    T: core::fmt::Debug,
+    S: Strategy<Value = T>,
+{
+    type Tree = ArrayValueTree<[S::Tree; LANES]>;
+    type Value = [T; LANES];
+
+    fn new_tree(&self, runner: &mut TestRunner) -> NewTree<Self> {
+        let tree: [S::Tree; LANES] = unsafe {
+            let mut tree: [MaybeUninit<S::Tree>; LANES] = MaybeUninit::uninit().assume_init();
+            for t in tree.iter_mut() {
+                *t = MaybeUninit::new(self.strategy.new_tree(runner)?)
+            }
+            core::mem::transmute_copy(&tree)
+        };
+        Ok(ArrayValueTree {
+            tree,
+            shrinker: 0,
+            last_shrinker: None,
+        })
+    }
+}
+
+impl<T: ValueTree, const LANES: usize> ValueTree for ArrayValueTree<[T; LANES]> {
+    type Value = [T::Value; LANES];
+
+    fn current(&self) -> Self::Value {
+        unsafe {
+            let mut value: [MaybeUninit<T::Value>; LANES] = MaybeUninit::uninit().assume_init();
+            for (tree_elem, value_elem) in self.tree.iter().zip(value.iter_mut()) {
+                *value_elem = MaybeUninit::new(tree_elem.current());
+            }
+            core::mem::transmute_copy(&value)
+        }
+    }
+
+    fn simplify(&mut self) -> bool {
+        while self.shrinker < LANES {
+            if self.tree[self.shrinker].simplify() {
+                self.last_shrinker = Some(self.shrinker);
+                return true;
+            } else {
+                self.shrinker += 1;
+            }
+        }
+
+        false
+    }
+
+    fn complicate(&mut self) -> bool {
+        if let Some(shrinker) = self.last_shrinker {
+            self.shrinker = shrinker;
+            if self.tree[shrinker].complicate() {
+                true
+            } else {
+                self.last_shrinker = None;
+                false
+            }
+        } else {
+            false
+        }
+    }
+}