Auto merge of rust-lang#138062 - LorrensP-2158466:miri-enable-float-nondet, r=<try>

Enable Non-determinism of float operations in Miri and change std tests

Links to [rust-lang#4208](rust-lang/miri#4208) and [rust-lang#3555](rust-lang/miri#3555) in Miri.

Non-determinism of floating point operations was disabled in rust-lang#137594 because it breaks the tests and doc-tests in core/coretests and std.

This PR:

- enables the float non-determinism but with a lower relative error of 4ULP instead of 16ULP
- changes tests that made incorrect assumptions about the operations not to make that assumption anymore (from `assert_eq!` to `assert_approx_eq!`.
- changes the `assert_approx_eq!` macro to allow up to 1e-4 to make the tests pass

TODO:
- I didn't touch the doc tests because I do not know nearly enough to come near them :)
- probably change the `assert_approx_eq` to use the same technique as Miri (i.e., using ULP instead of EPSILON)

try-job: x86_64-gnu-aux

Author: bors

library/coretests/tests/num/dec2flt/float.rs

@@ -4,7 +4,8 @@ use core::num::dec2flt::float::RawFloat;
 fn test_f32_integer_decode() {
     assert_eq!(3.14159265359f32.integer_decode(), (13176795, -22, 1));
     assert_eq!((-8573.5918555f32).integer_decode(), (8779358, -10, -1));
-    assert_eq!(2f32.powf(100.0).integer_decode(), (8388608, 77, 1));
+    // Set 2^100 directly instead of using powf, because it doesn't guarentee precision
+    assert_eq!(1.2676506e30_f32.integer_decode(), (8388608, 77, 1));
     assert_eq!(0f32.integer_decode(), (0, -150, 1));
     assert_eq!((-0f32).integer_decode(), (0, -150, -1));
     assert_eq!(f32::INFINITY.integer_decode(), (8388608, 105, 1));
@@ -20,7 +21,8 @@ fn test_f32_integer_decode() {
 fn test_f64_integer_decode() {
     assert_eq!(3.14159265359f64.integer_decode(), (7074237752028906, -51, 1));
     assert_eq!((-8573.5918555f64).integer_decode(), (4713381968463931, -39, -1));
-    assert_eq!(2f64.powf(100.0).integer_decode(), (4503599627370496, 48, 1));
+    // Set 2^100 directly instead of using powf, because it doesn't guarentee precision
+    assert_eq!(1.2676506002282294e30_f64.integer_decode(), (4503599627370496, 48, 1));
     assert_eq!(0f64.integer_decode(), (0, -1075, 1));
     assert_eq!((-0f64).integer_decode(), (0, -1075, -1));
     assert_eq!(f64::INFINITY.integer_decode(), (4503599627370496, 972, 1));

library/std/src/f32.rs

@@ -303,7 +303,7 @@ impl f32 {
     /// ```
     /// let x = 2.0_f32;
     /// let abs_difference = (x.powi(2) - (x * x)).abs();
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 8.0 * f32::EPSILON);
     ///
     /// assert_eq!(f32::powi(f32::NAN, 0), 1.0);
     /// ```
@@ -327,7 +327,7 @@ impl f32 {
     /// ```
     /// let x = 2.0_f32;
     /// let abs_difference = (x.powf(2.0) - (x * x)).abs();
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 8.0 * f32::EPSILON);
     ///
     /// assert_eq!(f32::powf(1.0, f32::NAN), 1.0);
     /// assert_eq!(f32::powf(f32::NAN, 0.0), 1.0);
@@ -387,7 +387,7 @@ impl f32 {
     /// // ln(e) - 1 == 0
     /// let abs_difference = (e.ln() - 1.0).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
@@ -412,7 +412,7 @@ impl f32 {
     /// // 2^2 - 4 == 0
     /// let abs_difference = (f.exp2() - 4.0).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 8.0 * f32::EPSILON);
     /// ```
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
@@ -441,7 +441,7 @@ impl f32 {
     /// // ln(e) - 1 == 0
     /// let abs_difference = (e.ln() - 1.0).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     ///
     /// Non-positive values:
@@ -478,7 +478,7 @@ impl f32 {
     /// // log5(5) - 1 == 0
     /// let abs_difference = (five.log(5.0) - 1.0).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     ///
     /// Non-positive values:
@@ -511,7 +511,7 @@ impl f32 {
     /// // log2(2) - 1 == 0
     /// let abs_difference = (two.log2() - 1.0).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     ///
     /// Non-positive values:
@@ -544,7 +544,7 @@ impl f32 {
     /// // log10(10) - 1 == 0
     /// let abs_difference = (ten.log10() - 1.0).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     ///
     /// Non-positive values:
@@ -650,7 +650,7 @@ impl f32 {
     /// // sqrt(x^2 + y^2)
     /// let abs_difference = (x.hypot(y) - (x.powi(2) + y.powi(2)).sqrt()).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
@@ -674,7 +674,7 @@ impl f32 {
     ///
     /// let abs_difference = (x.sin() - 1.0).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
@@ -698,7 +698,7 @@ impl f32 {
     ///
     /// let abs_difference = (x.cos() - 1.0).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
@@ -782,7 +782,7 @@ impl f32 {
     /// // acos(cos(pi/4))
     /// let abs_difference = (f.cos().acos() - std::f32::consts::FRAC_PI_4).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     #[doc(alias = "arccos")]
     #[rustc_allow_incoherent_impl]
@@ -882,8 +882,8 @@ impl f32 {
     /// let abs_difference_0 = (f.0 - x.sin()).abs();
     /// let abs_difference_1 = (f.1 - x.cos()).abs();
     ///
-    /// assert!(abs_difference_0 <= f32::EPSILON);
-    /// assert!(abs_difference_1 <= f32::EPSILON);
+    /// assert!(abs_difference_0 <= 4.0 * f32::EPSILON);
+    /// assert!(abs_difference_1 <= 4.0 * f32::EPSILON);
     /// ```
     #[doc(alias = "sincos")]
     #[rustc_allow_incoherent_impl]
@@ -1065,7 +1065,7 @@ impl f32 {
     ///
     /// let abs_difference = (f - x).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     #[doc(alias = "arcsinh")]
     #[rustc_allow_incoherent_impl]
@@ -1093,7 +1093,7 @@ impl f32 {
     ///
     /// let abs_difference = (f - x).abs();
     ///
-    /// assert!(abs_difference <= f32::EPSILON);
+    /// assert!(abs_difference <= 4.0 * f32::EPSILON);
     /// ```
     #[doc(alias = "arccosh")]
     #[rustc_allow_incoherent_impl]

library/std/src/f64.rs

@@ -303,7 +303,7 @@ impl f64 {
     /// ```
     /// let x = 2.0_f64;
     /// let abs_difference = (x.powi(2) - (x * x)).abs();
-    /// assert!(abs_difference <= f64::EPSILON);
+    /// assert!(abs_difference <= 8.0 * f64::EPSILON);
     ///
     /// assert_eq!(f64::powi(f64::NAN, 0), 1.0);
     /// ```
@@ -327,7 +327,7 @@ impl f64 {
     /// ```
     /// let x = 2.0_f64;
     /// let abs_difference = (x.powf(2.0) - (x * x)).abs();
-    /// assert!(abs_difference <= f64::EPSILON);
+    /// assert!(abs_difference <= 8.0 * f64::EPSILON);
     ///
     /// assert_eq!(f64::powf(1.0, f64::NAN), 1.0);
     /// assert_eq!(f64::powf(f64::NAN, 0.0), 1.0);

library/std/tests/floats/f32.rs

@@ -22,6 +22,11 @@ const NAN_MASK1: u32 = 0x002a_aaaa;
 /// Second pattern over the mantissa
 const NAN_MASK2: u32 = 0x0055_5555;
 
+/// Miri adds some extra errors to float functions; make sure the tests still pass.
+/// These values are purely used as a canary to test against and are thus not a stable guarantee Rust provides.
+/// They serve as a way to get an idea of the real precision of floating point operations on different platforms.
+const APPROX_DETLA: f32 = if cfg!(miri) { 1e-4 } else { 1e-6 };
+
 #[allow(unused_macros)]
 macro_rules! assert_f32_biteq {
     ($left : expr, $right : expr) => {
@@ -442,8 +447,12 @@ fn test_powi() {
     let nan: f32 = f32::NAN;
     let inf: f32 = f32::INFINITY;
     let neg_inf: f32 = f32::NEG_INFINITY;
-    assert_eq!(1.0f32.powi(1), 1.0);
-    assert_approx_eq!((-3.1f32).powi(2), 9.61);
+    assert_approx_eq!(1.0f32.powi(1), 1.0);
+    assert_approx_eq!(
+        (-3.1f32).powi(2),
+        9.61,
+        APPROX_DETLA /* Miri float-non-det: Make tests pass for now */
+    );
     assert_approx_eq!(5.9f32.powi(-2), 0.028727);
     assert_eq!(8.3f32.powi(0), 1.0);
     assert!(nan.powi(2).is_nan());
@@ -457,9 +466,17 @@ fn test_powf() {
     let inf: f32 = f32::INFINITY;
     let neg_inf: f32 = f32::NEG_INFINITY;
     assert_eq!(1.0f32.powf(1.0), 1.0);
-    assert_approx_eq!(3.4f32.powf(4.5), 246.408218);
+    assert_approx_eq!(
+        3.4f32.powf(4.5),
+        246.408218,
+        APPROX_DETLA /* Miri float-non-det: Make tests pass for now */
+    );
     assert_approx_eq!(2.7f32.powf(-3.2), 0.041652);
-    assert_approx_eq!((-3.1f32).powf(2.0), 9.61);
+    assert_approx_eq!(
+        (-3.1f32).powf(2.0),
+        9.61,
+        APPROX_DETLA /* Miri float-non-det: Make tests pass for now */
+    );
     assert_approx_eq!(5.9f32.powf(-2.0), 0.028727);
     assert_eq!(8.3f32.powf(0.0), 1.0);
     assert!(nan.powf(2.0).is_nan());
@@ -482,7 +499,11 @@ fn test_sqrt_domain() {
 fn test_exp() {
     assert_eq!(1.0, 0.0f32.exp());
     assert_approx_eq!(2.718282, 1.0f32.exp());
-    assert_approx_eq!(148.413162, 5.0f32.exp());
+    assert_approx_eq!(
+        148.413162,
+        5.0f32.exp(),
+        APPROX_DETLA /* Miri float-non-det: Make tests pass for now */
+    );
 
     let inf: f32 = f32::INFINITY;
     let neg_inf: f32 = f32::NEG_INFINITY;
@@ -494,7 +515,11 @@ fn test_exp() {
 
 #[test]
 fn test_exp2() {
-    assert_eq!(32.0, 5.0f32.exp2());
+    assert_approx_eq!(
+        32.0,
+        5.0f32.exp2(),
+        APPROX_DETLA /* Miri float-non-det: Make tests pass for now */
+    );
     assert_eq!(1.0, 0.0f32.exp2());
 
     let inf: f32 = f32::INFINITY;
@@ -517,17 +542,21 @@ fn test_ln() {
     assert!((-2.3f32).ln().is_nan());
     assert_eq!((-0.0f32).ln(), neg_inf);
     assert_eq!(0.0f32.ln(), neg_inf);
-    assert_approx_eq!(4.0f32.ln(), 1.386294);
+    assert_approx_eq!(
+        4.0f32.ln(),
+        1.386294,
+        APPROX_DETLA /* Miri float-non-det: Make tests pass for now */
+    );
 }
 
 #[test]
 fn test_log() {
     let nan: f32 = f32::NAN;
     let inf: f32 = f32::INFINITY;
     let neg_inf: f32 = f32::NEG_INFINITY;
-    assert_eq!(10.0f32.log(10.0), 1.0);
+    assert_approx_eq!(10.0f32.log(10.0), 1.0);
     assert_approx_eq!(2.3f32.log(3.5), 0.664858);
-    assert_eq!(1.0f32.exp().log(1.0f32.exp()), 1.0);
+    assert_approx_eq!(1.0f32.exp().log(1.0f32.exp()), 1.0);
     assert!(1.0f32.log(1.0).is_nan());
     assert!(1.0f32.log(-13.9).is_nan());
     assert!(nan.log(2.3).is_nan());
@@ -559,7 +588,7 @@ fn test_log10() {
     let nan: f32 = f32::NAN;
     let inf: f32 = f32::INFINITY;
     let neg_inf: f32 = f32::NEG_INFINITY;
-    assert_eq!(10.0f32.log10(), 1.0);
+    assert_approx_eq!(10.0f32.log10(), 1.0);
     assert_approx_eq!(2.3f32.log10(), 0.361728);
     assert_approx_eq!(1.0f32.exp().log10(), 0.434294);
     assert_eq!(1.0f32.log10(), 0.0);
@@ -639,7 +668,11 @@ fn test_acosh() {
     assert_approx_eq!(3.0f32.acosh(), 1.76274717403908605046521864995958461f32);
 
     // test for low accuracy from issue 104548
-    assert_approx_eq!(60.0f32, 60.0f32.cosh().acosh());
+    assert_approx_eq!(
+        60.0f32,
+        60.0f32.cosh().acosh(),
+        APPROX_DETLA /* Miri float-non-det: Make tests pass for now */
+    );
 }
 
 #[test]
@@ -718,7 +751,11 @@ fn test_real_consts() {
     let ln_10: f32 = consts::LN_10;
 
     assert_approx_eq!(frac_pi_2, pi / 2f32);
-    assert_approx_eq!(frac_pi_3, pi / 3f32);
+    assert_approx_eq!(
+        frac_pi_3,
+        pi / 3f32,
+        APPROX_DETLA /* Miri float-non-det: Make tests pass for now */
+    );
     assert_approx_eq!(frac_pi_4, pi / 4f32);
     assert_approx_eq!(frac_pi_6, pi / 6f32);
     assert_approx_eq!(frac_pi_8, pi / 8f32);

library/std/tests/floats/f64.rs

@@ -427,7 +427,7 @@ fn test_powi() {
     let nan: f64 = f64::NAN;
     let inf: f64 = f64::INFINITY;
     let neg_inf: f64 = f64::NEG_INFINITY;
-    assert_eq!(1.0f64.powi(1), 1.0);
+    assert_approx_eq!(1.0f64.powi(1), 1.0);
     assert_approx_eq!((-3.1f64).powi(2), 9.61);
     assert_approx_eq!(5.9f64.powi(-2), 0.028727);
     assert_eq!(8.3f64.powi(0), 1.0);
@@ -479,7 +479,7 @@ fn test_exp() {
 
 #[test]
 fn test_exp2() {
-    assert_eq!(32.0, 5.0f64.exp2());
+    assert_approx_eq!(32.0, 5.0f64.exp2());
     assert_eq!(1.0, 0.0f64.exp2());
 
     let inf: f64 = f64::INFINITY;
@@ -510,9 +510,9 @@ fn test_log() {
     let nan: f64 = f64::NAN;
     let inf: f64 = f64::INFINITY;
     let neg_inf: f64 = f64::NEG_INFINITY;
-    assert_eq!(10.0f64.log(10.0), 1.0);
+    assert_approx_eq!(10.0f64.log(10.0), 1.0);
     assert_approx_eq!(2.3f64.log(3.5), 0.664858);
-    assert_eq!(1.0f64.exp().log(1.0f64.exp()), 1.0);
+    assert_approx_eq!(1.0f64.exp().log(1.0f64.exp()), 1.0);
     assert!(1.0f64.log(1.0).is_nan());
     assert!(1.0f64.log(-13.9).is_nan());
     assert!(nan.log(2.3).is_nan());
@@ -544,7 +544,7 @@ fn test_log10() {
     let nan: f64 = f64::NAN;
     let inf: f64 = f64::INFINITY;
     let neg_inf: f64 = f64::NEG_INFINITY;
-    assert_eq!(10.0f64.log10(), 1.0);
+    assert_approx_eq!(10.0f64.log10(), 1.0);
     assert_approx_eq!(2.3f64.log10(), 0.361728);
     assert_approx_eq!(1.0f64.exp().log10(), 0.434294);
     assert_eq!(1.0f64.log10(), 0.0);