nir/lower_subgroups: Lower ballot intrinsics to the specified bit size
Ballot intrinsics return a bitfield of subgroups. In GLSL and some
SPIR-V extensions, they return a uint64_t. In SPV_KHR_shader_ballot,
they return a uvec4. Also, some back-ends would rather pass around
32-bit values because it's easier than messing with 64-bit all the time.
To solve this mess, we make nir_lower_subgroups take a new parameter
called ballot_bit_size and it lowers whichever thing it gets in from the
source language (uint64_t or uvec4) to a scalar with the specified
number of bits. This replaces a chunk of the old lowering code.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
5 files changed