There's nothing inherently fixed-width in the code. All that's required
to generalize it is to make everything internally 64-bit and pass
UINT_BITS in as a parameter to util_compute_fast_[us]div_info. With
that, it can now handle 8, 16, 32, and 64-bit integer division by a
constant.
We also add support for division by 1 and by other powers of 2. This is
useful if you want to divide by a uniform value in a shader where you
have the opportunity to adjust the uniform on the CPU before passing it
in.
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Compilers can use this to generate optimal code for integer division
by a constant.
Additionally, an unsigned division by a uniform that is constant but not
known at compile time can still be optimized by passing 2-4 division
factors to the shader as uniforms and executing one of the fast_udiv*
variants. The signed division algorithm doesn't have this capability.
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Marek Olšák
Jason Ekstrand