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Treat wasmtime::component::Val::Float{32,64} zero and negative zero as inequal (#5562)

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Following up on #5535, treat positive and negative zero as inequal in
wasmtime::component::Val::Float{32,64}'s `PartialEq` logic. IEEE 754
equality considers these values equal, but they are semantically
distinct values, and testing and fuzzing should be aware of the
difference.
This commit is contained in:
Dan Gohman
2023-01-11 16:24:39 -08:00
committed by GitHub
parent 6cb68f3287
commit 6a20ca5512
1 changed files with 15 additions and 3 deletions
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18
crates/wasmtime/src/component/values.rs
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@@ -1007,10 +1007,22 @@ impl Val {
impl PartialEq for Val {
fn eq(&self, other: &Self) -> bool {
match (self, other) {
// This breaks conformance with IEEE-754 equality to simplify testing logic.
(Self::Float32(l), Self::Float32(r)) => l == r || (l.is_nan() && r.is_nan()),
// IEEE 754 equality considers NaN inequal to NaN and negative zero
// equal to positive zero, however we do the opposite here, because
// this logic is used by testing and fuzzing, which want to know
// whether two values are semantically the same, rather than
// numerically equal.
(Self::Float32(l), Self::Float32(r)) => {
(*l != 0.0 && l == r)
|| (*l == 0.0 && l.to_bits() == r.to_bits())
|| (l.is_nan() && r.is_nan())
}
(Self::Float32(_), _) => false,
(Self::Float64(l), Self::Float64(r)) => l == r || (l.is_nan() && r.is_nan()),
(Self::Float64(l), Self::Float64(r)) => {
(*l != 0.0 && l == r)
|| (*l == 0.0 && l.to_bits() == r.to_bits())
|| (l.is_nan() && r.is_nan())
}
(Self::Float64(_), _) => false,
(Self::Bool(l), Self::Bool(r)) => l == r,