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Yevhenii Kolesnikov authored
From the Kaby Lake PRM Vol. 7 "Assigning Conditional Flags": * Note that the [post condition signal] bits generated at the output of a compute are before the .sat. Paragraph about post_zero does not mention saturation, but testing it on actual GPUs shows that conditional modifiers are applied after saturation. * post_zero bit: This bit reflects whether the final result is zero after all the clamping, normalizing, or format conversion logic. For signed types we don't care about saturation: it won't change the result of conditional modifier. For floating and unsigned types there two special cases, when we can remove inst even if scan_inst is saturated: G and LE. Since conditional modifiers are just comparations against zero, saturating positive values to the upper limit never changes the result of comparation. For negative values: (sat(x) > 0) == (x > 0) --- false (sat(x) <= 0) == (x <= 0) --- true Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/2610 Signed-off-by: Yevhenii Kolesnikov <yevhenii.kolesnikov@globallogic.com> Reviewed-by: Matt Turner <mattst88@gmail.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4167>
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