Add a helper for cached test inputs

Add a type that caches values used to implement `GenerateInput` on a
variety of signatures.

library/compiler-builtins/libm/crates/libm-test/src/gen.rs

@@ -0,0 +1,71 @@
+//! Different generators that can create random or systematic bit patterns.
+
+use crate::GenerateInput;
+
+/// Helper type to turn any reusable input into a generator.
+#[derive(Clone, Debug, Default)]
+pub struct CachedInput {
+    pub inputs_f32: Vec<(f32, f32, f32)>,
+    pub inputs_f64: Vec<(f64, f64, f64)>,
+    pub inputs_i32: Vec<(i32, i32, i32)>,
+}
+
+impl GenerateInput<(f32,)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (f32,)> {
+        self.inputs_f32.iter().map(|f| (f.0,))
+    }
+}
+
+impl GenerateInput<(f32, f32)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (f32, f32)> {
+        self.inputs_f32.iter().map(|f| (f.0, f.1))
+    }
+}
+
+impl GenerateInput<(i32, f32)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (i32, f32)> {
+        self.inputs_i32.iter().zip(self.inputs_f32.iter()).map(|(i, f)| (i.0, f.0))
+    }
+}
+
+impl GenerateInput<(f32, i32)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (f32, i32)> {
+        GenerateInput::<(i32, f32)>::get_cases(self).map(|(i, f)| (f, i))
+    }
+}
+
+impl GenerateInput<(f32, f32, f32)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (f32, f32, f32)> {
+        self.inputs_f32.iter().copied()
+    }
+}
+
+impl GenerateInput<(f64,)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (f64,)> {
+        self.inputs_f64.iter().map(|f| (f.0,))
+    }
+}
+
+impl GenerateInput<(f64, f64)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (f64, f64)> {
+        self.inputs_f64.iter().map(|f| (f.0, f.1))
+    }
+}
+
+impl GenerateInput<(i32, f64)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (i32, f64)> {
+        self.inputs_i32.iter().zip(self.inputs_f64.iter()).map(|(i, f)| (i.0, f.0))
+    }
+}
+
+impl GenerateInput<(f64, i32)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (f64, i32)> {
+        GenerateInput::<(i32, f64)>::get_cases(self).map(|(i, f)| (f, i))
+    }
+}
+
+impl GenerateInput<(f64, f64, f64)> for CachedInput {
+    fn get_cases(&self) -> impl Iterator<Item = (f64, f64, f64)> {
+        self.inputs_f64.iter().copied()
+    }
+}

library/compiler-builtins/libm/crates/libm-test/src/lib.rs

@@ -1,3 +1,4 @@
+pub mod gen;
 mod num_traits;
 mod test_traits;