diff --git a/src/math/fma.rs b/src/math/fma.rs index 07d90f8b7..99f77bc79 100644 --- a/src/math/fma.rs +++ b/src/math/fma.rs @@ -126,8 +126,8 @@ pub fn fma(x: f64, y: f64, z: f64) -> f64 { } else { /* r -= z */ let t = rlo; - rlo -= zlo; - rhi = rhi - zhi - (t < rlo) as u64; + rlo = rlo.wrapping_sub(zlo); + rhi = rhi.wrapping_sub(zhi.wrapping_sub((t < rlo) as u64)); if (rhi >> 63) != 0 { rlo = (-(rlo as i64)) as u64; rhi = (-(rhi as i64)) as u64 - (rlo != 0) as u64; @@ -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,); + } +}