From 5b950eaea2bb38d4974ecc5a96231df6dc42fc99 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Thu, 12 Jul 2018 12:20:55 -0500
Subject: [PATCH] use approximate equality with 1 ULP of tolerance

---
 library/compiler-builtins/libm/src/lib.rs                 | 6 ++++++
 library/compiler-builtins/libm/test-generator/src/main.rs | 6 +++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/library/compiler-builtins/libm/src/lib.rs b/library/compiler-builtins/libm/src/lib.rs
index 3d4062f3d4ab..cb2110f1fb74 100644
--- a/library/compiler-builtins/libm/src/lib.rs
+++ b/library/compiler-builtins/libm/src/lib.rs
@@ -10,3 +10,9 @@ pub use fabsf::fabsf;
 pub use powf::powf;
 pub use scalbnf::scalbnf;
 pub use sqrtf::sqrtf;
+
+/// Approximate equality with 1 ULP of tolerance
+#[doc(hidden)]
+pub fn _eqf(a: u32, b: u32) -> bool {
+    (a as i32).wrapping_sub(b as i32).abs() <= 1
+}
diff --git a/library/compiler-builtins/libm/test-generator/src/main.rs b/library/compiler-builtins/libm/test-generator/src/main.rs
index 7ee956f730f3..c406cf340ed1 100644
--- a/library/compiler-builtins/libm/test-generator/src/main.rs
+++ b/library/compiler-builtins/libm/test-generator/src/main.rs
@@ -65,7 +65,7 @@ macro_rules! f32_f32 {
                             let outi = outf.to_bits();
 
                             if !((outf.is_nan() && f32::from_bits(expected).is_nan()) ||
-                                 outi == expected) {{
+                                 libm::_eqf(outi, expected)) {{
                                 panic!(
                                     \"input: {{}}, output: {{}}, expected: {{}}\",
                                     inp,
@@ -124,7 +124,7 @@ macro_rules! f32f32_f32 {
                             let outi = outf.to_bits();
 
                             if !((outf.is_nan() && f32::from_bits(expected).is_nan()) ||
-                                 outi == expected) {{
+                                 libm::_eqf(outi, expected)) {{
                                 panic!(
                                     \"input: {{:?}}, output: {{}}, expected: {{}}\",
                                     (i1, i2),
@@ -182,7 +182,7 @@ macro_rules! f32i32_f32 {
                             let outi = outf.to_bits();
 
                             if !((outf.is_nan() && f32::from_bits(expected).is_nan()) ||
-                                 outi == expected) {{
+                                 libm::_eqf(outi, expected)) {{
                                 panic!(
                                     \"input: {{:?}}, output: {{}}, expected: {{}}\",
                                     (i1, i2),