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The goal here is to generate addresses that are a right-shifted version of the actual byte address and record the shift amount in the offset_shift index. While we could just insert a ushr at the end of deref chains, this will prevent the shift to be optimized away in many cases. Instead, we try to extract the shift from the array strides and struct offsets that make up the deref chain, and only insert a ushr when absolutely necessary (i.e., for casts). This means we have to walk the entire deref chain at once for accesses that support offset_shift and we don't use the standard algorithm of replacing each deref one at a time. To be able to legally right-shift casts, we use the alignment information and never shift more than what the alignment could support. It should also be noted that casts generally have two sources: something provided by the driver (e.g., a Vulkan resource index) or a variable pointer coming from a phi/bcsel. For the latter, the entire access chain consists of multiple parts that are ended by either a phi/bcsel or an access. Only the part the ends in an access is handled by this new algorithm; the other parts are handled as usual. This is necessary because we have no way to encode the offset shift or to even know how much we would be able to shift without knowing how it is accessed. This commit adds the general implementation for lowering accesses using offset_shift and adds a compiler option for drivers to enable it for SSBO accesses. Signed-off-by: Job Noorman <jnoorman@igalia.com> Reviewed-by: Emma Anholt <emma@anholt.net> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35092> |
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| clc | ||
| glsl | ||
| isaspec | ||
| libcl | ||
| nir | ||
| rust | ||
| spirv | ||
| builtin_types.py | ||
| builtin_types_c.py | ||
| builtin_types_h.py | ||
| glsl_types.c | ||
| glsl_types.h | ||
| list.h | ||
| meson.build | ||
| shader_enums.c | ||
| shader_enums.h | ||
| shader_info.h | ||