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eddybeddyb
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fuzz: add float->float->float roundtrip ops (through f32/Single and f64/Double).
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2 files changed

+60
-8
lines changed

2 files changed

+60
-8
lines changed

‎fuzz/ops.rs

+50-6
Original file line numberDiff line numberDiff line change
@@ -25,13 +25,15 @@ enum OpKind {
2525
enum Type {
2626
SInt(usize),
2727
UInt(usize),
28+
Float(usize),
2829
}
2930

3031
impl Type {
3132
fn rust_type(&self) -> String {
3233
match self {
3334
Type::SInt(w) => format!("i{w}"),
3435
Type::UInt(w) => format!("u{w}"),
36+
Type::Float(w) => format!("f{w}"),
3537
}
3638
}
3739
}
@@ -60,6 +62,8 @@ const OPS: &[(&str, OpKind)] = &[
6062
// Roundtrip (`F -> T -> F`) ops.
6163
("FToI128ToF", Roundtrip(Type::SInt(128))),
6264
("FToU128ToF", Roundtrip(Type::UInt(128))),
65+
("FToSingleToF", Roundtrip(Type::Float(32))),
66+
("FToDoubleToF", Roundtrip(Type::Float(64))),
6367
];
6468

6569
fn all_ops_map_concat(f: impl Fn(usize, &'static str, &OpKind) -> String) -> String {
@@ -132,9 +136,13 @@ impl<HF> FuzzOp<HF>
132136
where
133137
HF: num_traits::Float
134138
+ num_traits::AsPrimitive<i128>
135-
+ num_traits::AsPrimitive<u128>,
139+
+ num_traits::AsPrimitive<u128>
140+
+ num_traits::AsPrimitive<f32>
141+
+ num_traits::AsPrimitive<f64>,
136142
i128: num_traits::AsPrimitive<HF>,
137143
u128: num_traits::AsPrimitive<HF>,
144+
f32: num_traits::AsPrimitive<HF>,
145+
f64: num_traits::AsPrimitive<HF>,
138146
{
139147
fn eval_hard(self) -> HF {
140148
match self {
@@ -163,8 +171,15 @@ impl<HF> FuzzOp<HF>
163171
}
164172
}
165173
166-
impl<RustcApFloat: rustc_apfloat::Float> FuzzOp<RustcApFloat> {
167-
fn eval_rs_apf(self) -> RustcApFloat {
174+
impl<F> FuzzOp<F>
175+
where
176+
F: rustc_apfloat::Float
177+
+ rustc_apfloat::FloatConvert<rustc_apfloat::ieee::Single>
178+
+ rustc_apfloat::FloatConvert<rustc_apfloat::ieee::Double>,
179+
rustc_apfloat::ieee::Single: rustc_apfloat::FloatConvert<F>,
180+
rustc_apfloat::ieee::Double: rustc_apfloat::FloatConvert<F>,
181+
{
182+
fn eval_rs_apf(self) -> F {
168183
match self {
169184
" + &all_ops_map_concat(|_tag, name, kind| {
170185
let inputs = kind.inputs(&["a", "b", "c"]);
@@ -178,9 +193,23 @@ impl<RustcApFloat: rustc_apfloat::Float> FuzzOp<RustcApFloat> {
178193
let (w, i_or_u) = match ty {
179194
Type::SInt(w) => (w, "i"),
180195
Type::UInt(w) => (w, "u"),
196+
Type::Float(_) => unreachable!(),
197+
};
198+
format!(
199+
"F::from_{i_or_u}128({}.to_{i_or_u}128({w}).value).value",
200+
inputs[0],
201+
)
202+
}
203+
Roundtrip(Type::Float(w)) => {
204+
let rs_apf_type = match w {
205+
32 => "rustc_apfloat::ieee::Single",
206+
64 => "rustc_apfloat::ieee::Double",
207+
_ => unreachable!(),
181208
};
182209
format!(
183-
"RustcApFloat::from_{i_or_u}128({}.to_{i_or_u}128({w}).value).value",
210+
"rustc_apfloat::FloatConvert
211+
::convert(rustc_apfloat::FloatConvert::<{rs_apf_type}>
212+
::convert({}, &mut false).value, &mut false).value",
184213
inputs[0],
185214
)
186215
}
@@ -230,7 +259,7 @@ struct FuzzOp {
230259
// HACK(eddyb) 'scratch' variables used by expressions below.
231260
APFloat r(0.0);
232261
APSInt i;
233-
bool isExact;
262+
bool scratch_bool;
234263
235264
switch(tag) {
236265
"
@@ -255,16 +284,31 @@ struct FuzzOp {
255284
let (w, signed) = match ty {
256285
Type::SInt(w) => (w, true),
257286
Type::UInt(w) => (w, false),
287+
Type::Float(_) => unreachable!(),
258288
};
259289
format!(
260290
"((r = {}),
261291
(i = APSInt({w}, !{signed})),
262-
r.convertToInteger(i, APFloat::rmTowardZero, &isExact),
292+
r.convertToInteger(i, APFloat::rmTowardZero, &scratch_bool),
263293
r.convertFromAPInt(i, {signed}, APFloat::rmNearestTiesToEven),
264294
r)",
265295
inputs[0]
266296
)
267297
}
298+
Roundtrip(Type::Float(w)) => {
299+
let cxx_apf_semantics = match w {
300+
32 => "APFloat::IEEEsingle()",
301+
64 => "APFloat::IEEEdouble()",
302+
_ => unreachable!(),
303+
};
304+
format!(
305+
"((r = {input}),
306+
r.convert({cxx_apf_semantics}, APFloat::rmNearestTiesToEven, &scratch_bool),
307+
r.convert({input}.getSemantics(), APFloat::rmNearestTiesToEven, &scratch_bool),
308+
r)",
309+
input = inputs[0]
310+
)
311+
}
268312
};
269313
format!(
270314
"

‎fuzz/src/main.rs

+10-2
Original file line numberDiff line numberDiff line change
@@ -47,7 +47,10 @@ enum Commands {
4747
/// all types implementing this trait *must* be annotated with `#[repr(C, packed)]`,
4848
/// and `ops.rs` *must* also ensure exactly matching layout for the C++ counterpart.
4949
trait FloatRepr: Copy + Default + Eq + fmt::Display {
50-
type RustcApFloat: rustc_apfloat::Float;
50+
type RustcApFloat: rustc_apfloat::Float
51+
+ rustc_apfloat::Float
52+
+ rustc_apfloat::FloatConvert<rustc_apfloat::ieee::Single>
53+
+ rustc_apfloat::FloatConvert<rustc_apfloat::ieee::Double>;
5154

5255
const BIT_WIDTH: usize = Self::RustcApFloat::BITS;
5356
const BYTE_LEN: usize = (Self::BIT_WIDTH + 7) / 8;
@@ -223,7 +226,12 @@ impl<F: FloatRepr> FuzzOpEvalOutputs<F> {
223226
}
224227
}
225228

226-
impl<F: FloatRepr> FuzzOp<F> {
229+
impl<F: FloatRepr> FuzzOp<F>
230+
// FIXME(eddyb) such bounds shouldn't be here, but `FloatRepr` can't imply them.
231+
where
232+
rustc_apfloat::ieee::Single: rustc_apfloat::FloatConvert<F::RustcApFloat>,
233+
rustc_apfloat::ieee::Double: rustc_apfloat::FloatConvert<F::RustcApFloat>,
234+
{
227235
fn try_decode(data: &[u8]) -> Result<Self, ()> {
228236
let (&tag, inputs) = data.split_first().ok_or(())?;
229237
if inputs.len() % F::BYTE_LEN != 0 {

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