fix overflow

Author: tgross35

crates/libm-test/src/gen/case_list.rs

@@ -429,7 +429,16 @@ fn frexpf_cases() -> Vec<TestCase<op::frexpf::Routine>> {
 }
 
 fn hypot_cases() -> Vec<TestCase<op::hypot::Routine>> {
-    vec![]
+    let mut v = vec![];
+    TestCase::append_pairs(
+        &mut v,
+        &[(
+            // Case that can overflow exponent if wrapping arithmetic is not used
+            (hf64!("-0x1.800f800f80100p+1023"), hf64!("0x1.8354835473720p+996")),
+            Some(hf64!("0x1.800f800f80100p+1023")),
+        )],
+    );
+    v
 }
 
 fn hypotf_cases() -> Vec<TestCase<op::hypotf::Routine>> {

src/math/hypot.rs

@@ -118,7 +118,7 @@ fn cr_hypot(mut x: f64, mut y: f64) -> f64 {
     ex = thd;
     ey = tld;
     ex &= 0x7ff_u64 << 52;
-    let aidr: u64 = ey + (0x3fe_u64 << 52) - ex;
+    let aidr: u64 = ey.wrapping_add(0x3fe_u64 << 52).wrapping_sub(ex);
     let mid: u64 = (aidr.wrapping_sub(0x3c90000000000000) + 16) >> 5;
     if mid == 0 || !(0x39b0000000000000_u64..=0x3c9fffffffffff80_u64).contains(&aidr) {
         cold_path();