Rollup merge of #121062 - RustyYato:f32-midpoint, r=the8472 · model-checking/verify-rust-std@380d9a3 (original) (raw)
`@@ -729,7 +729,7 @@ assume_usize_width! {
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`macro_rules! test_float {
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`-
($modname: ident, fty:ty,fty: ty, fty:ty,inf: expr, neginf:expr,neginf: expr, neginf:expr,nan: expr, min:expr,min: expr, min:expr,max: expr, $min_pos: expr) => {
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($modname: ident, fty:ty,fty: ty, fty:ty,inf: expr, neginf:expr,neginf: expr, neginf:expr,nan: expr, min:expr,min: expr, min:expr,max: expr, minpos:expr,min_pos: expr, minpos:expr,max_exp:expr) => {
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`mod $modname {
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` #[test]
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`fn min() {
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`@@ -880,6 +880,27 @@ macro_rules! test_float {
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` assert!(($nan as $fty).midpoint(1.0).is_nan());
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` assert!((1.0 as fty).midpoint(fty).midpoint(fty).midpoint(nan).is_nan());
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` assert!(($nan as fty).midpoint(fty).midpoint(fty).midpoint(nan).is_nan());
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// test if large differences in magnitude are still correctly computed.
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// NOTE: that because of how small x and y are, x + y can never overflow
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// so (x + y) / 2.0 is always correct
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// in particular, 2.pow(i) will never be at the max exponent, so it could
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// be safely doubled, while j is significantly smaller.
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for i in maxexp.saturatingsub(64)..max_exp.saturating_sub(64)..maxexp.saturatingsub(64)..max_exp {
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for j in 0..64u8 {
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let large = <$fty>::from(2.0f32).powi(i);
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// a much smaller number, such that there is no chance of overflow to test
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// potential double rounding in midpoint's implementation.
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let small = <$fty>::from(2.0f32).powi($max_exp - 1)
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- <$fty>::EPSILON
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- <$fty>::from(j);
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``
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let naive = (large + small) / 2.0;
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let midpoint = large.midpoint(small);
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assert_eq!(naive, midpoint);
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}
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}
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`}
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` #[test]
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`fn rem_euclid() {
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`@@ -912,7 +933,8 @@ test_float!(
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`f32::NAN,
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`f32::MIN,
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`f32::MAX,
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f32::MIN_POSITIVE
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f32::MIN_POSITIVE,
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f32::MAX_EXP
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`);
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`test_float!(
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`f64,
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`@@ -922,5 +944,6 @@ test_float!(
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`f64::NAN,
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`f64::MIN,
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`f64::MAX,
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f64::MIN_POSITIVE
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f64::MIN_POSITIVE,
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f64::MAX_EXP
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`);
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