Add FMA tests that cause it to segfault

library/compiler-builtins/libm/src/math/fma.rs

@@ -205,3 +205,22 @@ pub fn fma(x: f64, y: f64, z: f64) -> f64 {
     }
     scalbn(r, e)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn fma_segfault() {
+        // These two inputs cause fma to segfault on release due to overflow:
+        assert_eq!(
+            fma(
+                -0.0000000000000002220446049250313,
+                -0.0000000000000002220446049250313,
+                -0.0000000000000002220446049250313
+            ),
+            -0.00000000000000022204460492503126,
+        );
+
+        assert_eq!(fma(-0.992, -0.992, -0.992), -0.00793599999988632,);
+    }
+}

library/compiler-builtins/libm/tests/unit.rs

@@ -0,0 +1,19 @@
+use libm::*;
+
+#[test]
+fn fma_segfault() {
+    // These two inputs cause fma to segfault on release due to overflow:
+    assert_eq!(
+        fma(
+            -0.0000000000000002220446049250313,
+            -0.0000000000000002220446049250313,
+            -0.0000000000000002220446049250313
+        ),
+        -0.00000000000000022204460492503126,
+    );
+
+    assert_eq!(
+        fma(-0.992, -0.992, -0.992),
+        -0.00793599999988632,
+    );
+}