Auto merge of rust-lang#147818 - rperier:unify_and_dedup_max_recip_float_tests, r=tgross35

Unify and deduplicate max recip float tests

cc rust-lang#141726

This is a proposal to unify and deduplicate max recip tests for f16 and f128

Author: bors

library/coretests/tests/floats/f128.rs

@@ -1,8 +1,6 @@
 // FIXME(f16_f128): only tested on platforms that have symbols and aren't buggy
 #![cfg(target_has_reliable_f128)]
 
-#[cfg(any(miri, target_has_reliable_f128_math))]
-use super::assert_approx_eq;
 use super::assert_biteq;
 
 // Note these tolerances make sense around zero, but not for more extreme exponents.
@@ -20,16 +18,6 @@ const TOL_PRECISE: f128 = 1e-28;
 // FIXME(f16_f128,miri): many of these have to be disabled since miri does not yet support
 // the intrinsics.
 
-#[test]
-#[cfg(any(miri, target_has_reliable_f128_math))]
-fn test_max_recip() {
-    assert_approx_eq!(
-        f128::MAX.recip(),
-        8.40525785778023376565669454330438228902076605e-4933,
-        1e-4900
-    );
-}
-
 #[test]
 fn test_from() {
     assert_biteq!(f128::from(false), 0.0);

library/coretests/tests/floats/f16.rs

@@ -1,7 +1,7 @@
 // FIXME(f16_f128): only tested on platforms that have symbols and aren't buggy
 #![cfg(target_has_reliable_f16)]
 
-use super::{assert_approx_eq, assert_biteq};
+use super::assert_biteq;
 
 /// Tolerance for results on the order of 10.0e-2
 #[allow(unused)]
@@ -22,12 +22,6 @@ const TOL_P4: f16 = 10.0;
 // FIXME(f16_f128,miri): many of these have to be disabled since miri does not yet support
 // the intrinsics.
 
-#[test]
-#[cfg(any(miri, target_has_reliable_f16_math))]
-fn test_max_recip() {
-    assert_approx_eq!(f16::MAX.recip(), 1.526624e-5f16, 1e-4);
-}
-
 #[test]
 fn test_from() {
     assert_biteq!(f16::from(false), 0.0);

library/coretests/tests/floats/mod.rs

@@ -38,6 +38,8 @@ trait TestableFloat: Sized {
     const MUL_ADD_RESULT: Self;
     /// The result of (-12.3).mul_add(-4.5, -6.7)
     const NEG_MUL_ADD_RESULT: Self;
+    /// Reciprocal of the maximum val
+    const MAX_RECIP: Self;
 }
 
 impl TestableFloat for f16 {
@@ -64,6 +66,7 @@ impl TestableFloat for f16 {
     const RAW_MINUS_14_DOT_25: Self = Self::from_bits(0xcb20);
     const MUL_ADD_RESULT: Self = 62.031;
     const NEG_MUL_ADD_RESULT: Self = 48.625;
+    const MAX_RECIP: Self = 1.526624e-5;
 }
 
 impl TestableFloat for f32 {
@@ -92,6 +95,7 @@ impl TestableFloat for f32 {
     const RAW_MINUS_14_DOT_25: Self = Self::from_bits(0xc1640000);
     const MUL_ADD_RESULT: Self = 62.05;
     const NEG_MUL_ADD_RESULT: Self = 48.65;
+    const MAX_RECIP: Self = 2.938736e-39;
 }
 
 impl TestableFloat for f64 {
@@ -116,6 +120,7 @@ impl TestableFloat for f64 {
     const RAW_MINUS_14_DOT_25: Self = Self::from_bits(0xc02c800000000000);
     const MUL_ADD_RESULT: Self = 62.050000000000004;
     const NEG_MUL_ADD_RESULT: Self = 48.650000000000006;
+    const MAX_RECIP: Self = 5.562684646268003e-309;
 }
 
 impl TestableFloat for f128 {
@@ -140,6 +145,7 @@ impl TestableFloat for f128 {
     const RAW_MINUS_14_DOT_25: Self = Self::from_bits(0xc002c800000000000000000000000000);
     const MUL_ADD_RESULT: Self = 62.0500000000000000000000000000000037;
     const NEG_MUL_ADD_RESULT: Self = 48.6500000000000000000000000000000049;
+    const MAX_RECIP: Self = 8.40525785778023376565669454330438228902076605e-4933;
 }
 
 /// Determine the tolerance for values of the argument type.
@@ -1425,13 +1431,15 @@ float_test! {
         let nan: Float = Float::NAN;
         let inf: Float = Float::INFINITY;
         let neg_inf: Float = Float::NEG_INFINITY;
+        let max: Float = Float::MAX;
         assert_biteq!((1.0 as Float).recip(), 1.0);
         assert_biteq!((2.0 as Float).recip(), 0.5);
         assert_biteq!((-0.4 as Float).recip(), -2.5);
         assert_biteq!((0.0 as Float).recip(), inf);
         assert!(nan.recip().is_nan());
         assert_biteq!(inf.recip(), 0.0);
         assert_biteq!(neg_inf.recip(), -0.0);
+        assert_biteq!(max.recip(), Float::MAX_RECIP);
     }
 }