Memory fences do not refer to an element of a binding table. Rather,
the reason we had "BTI" in these opcodes was to distinguish what in
modern terms are called UGM (untyped memory data cache) vs. SLM
(cross-thread shared local memory) fences.
Icelake and older platforms used the "data cache" SFID for both
purposes, distinguishing them by having a special binding table
index, 254, meaning "this is actually SLM access". This is where
the notion that fences had BTIs came in. (In fact, prior to Icelake,
separate SLM fences were not a thing, so BTI wasn't used there either.)
To avoid confusion about BTI being involved, we choose a simpler lie: we
have Icelake SLM fences target GFX12_SFID_SLM (like modern platforms
would), even though it didn't really exist back then. Later lowering
code sets it back to the correct Data Cache SFID with magic SLM binding
table index. This eliminates BTI everywhere and an unnecessary source.
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33297>
brw_memory_fence() overrides the instructions generated by the
MEMORY_FENCE or INTERLOCK opcodes to be force_writemask_all with
exec_size == 1. But the IR was emitting it in SIMD8 (regardless
of dispatch width). Instead, just emit the IR as SIMD1/NoMask so
the IR matches what we actually generate. Have size_written indicate
that the entire destination is written, however, as it is ultimately
going to be a SEND that writes a whole register.
We were also using a UD register for the source of
FS_OPCODE_SCHEDULING_FENCE when the generator overrides it to UW,
so just specify UW in the IR as well so that they line up.
Also add validation for MEMORY_FENCE/INTERLOCK that we've done the
exec_size and masking right in the IR.
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33297>
