• Benedikt Meurer's avatar
    [turbofan] Fix -0 check for subnormals. · 56f6a763
    Benedikt Meurer authored
    Previously we'd check `x` for -0 by testing `(1.0 / x) == -Infinity`,
    but this will yield the wrong results when `x` is a subnormal, i.e.
    really close to 0.
    
    In CSA we already perform bit checks to test for -0, so teach TurboFan
    to do the same for comparisons to -0 (via `Object.is`). We introduce a
    new NumberIsMinusZero simplified operator to handle the case where
    SimplifiedLowering already knows that the input is a number.
    
    Bug: chromium:903043, v8:6882
    Change-Id: I0cb7c568029b461a92fc183104d5f359b4bfe7f4
    Reviewed-on: https://chromium-review.googlesource.com/c/1328802
    Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
    Reviewed-by: 's avatarSigurd Schneider <sigurds@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#57382}
    56f6a763
simplified-operator.h 29.4 KB