The mantissa for a float doesn't contain enough data to accurately represent
the min/max values for some destination types. Instead of clamping before
converting, clamp after converting when coming from floats. This improves
conformance of CL conversions, specifically for float -> long/ulong with
int64 emulation enabled.
Refactors the limit determination from the clamp, so we can determine
limits for the dest type (int/uint) in both the source (float) and dest
type. The limit as a float is used for comparison, while the limit as a
dest type is used for bcsel.
Important note is that the comparison is inverted to fge instead of flt,
so the bcsel chooses the direct int/uint over the converted float in the
case where the comparison comes up equal, but the conversion can't produce
the exact min/max value.
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8256>
Most of these were originally written by Daniel Stone in the Microsoft
ClOn12 branch, reworked by Jesse Natalie, fixed by Boris Brezillon, and
possibly touched by others along the way. Unfortunately, none of that
is in the commit history thanks to living in the CLOn12 branch.
I ported them to mesa master and further reworked things for better
cosmetics. In particular,
1. They now live in a builder helper rather than in vtn_alu.c.
2. Instead of looping inside each builder helper, we just trust NIR
vector instructions to handle vectors.
3. Lots of re-arranging of the helpers for clarity, better asserting,
and better re-use with the upcoming lowering pass.
Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6945>
