This will be useful for pulling constants in device bound shaders. A64
allows us to put the constants anywhere.
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32895>
There were 4 fields:
- key: now will be passed explicitly, so we can reuse the existing
more general fs_visitor constructor;
- input_vue_map: used only by the client code brw_compile_gs, so
create it separatedly as a local variable;
- two unsigned parameters: just put them inside a nested struct in the
shader.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33228>
After optimization happen, if the sources are still in one or two
contigous spans for some reason (e.g. some data read from memory
now being written), it is beneficial to just use regular SEND
and avoid having to set the ARF scalar instruction.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Lionel Landwerlin <None>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32410>
Add an optimization pass to turn regular SENDs into SEND_GATHERs.
This allows the payload to be "broken" into smaller pieces that
can be further optimized, which _may_ result in
- less register pressure (no need to contiguous space), and
- less instructions (no need to MOV to such space).
For debugging, the INTEL_DEBUG=no-send-gather option skips this
optimization, and reporting how many opportunities were missed.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Lionel Landwerlin <None>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32410>
This limits the address register to simple cases inside a block.
Validation ensures that the address register is only written once and
read once.
Instruction scheduling makes sure that instructions using the address
register in the generator are not scheduled while there is an usage of
the register in the IR.
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28199>
The push_constant_loc[] array is always an identity mapping these days,
so it's kind of pointless. Just use the original uniform number and
skip the unnecessary "remap" step. With that gone, and shrinking UBO
ranges gone, assign_constant_locations() is now empty and can be removed
as well.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32841>
Now that we never shrink ranges in the backend, we never lower push
constants to pull constants late in the backend either. get_pull_loc
will never return true, and so all of brw_lower_constant_loads becomes
a noop.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32841>
This commit used to be "brw/emit: Allow scalar sources to 64-bit
3-source instructions". These instructions were fixed up in
brw_eu_emit. There seems to be some conflict with the <0,1,0> stride an
post-RA scheduling. The only difference between the passing code
generated by this commit and the failing code generated by the older
commit is some post-RA scheduling.
v2: Change the stride of a MAD even if the instruction isn't
lowered. MAD instructions that are already SIMD8 have to follow the same
rules. 🤦
v3: Pull the lowering out to its own pass. Update the comment in
brw_fs_validate. Suggested by Ken.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29884>
Almost all cases now handled with default arguments. The only real
extra work that was being done was pushed to the client code in
debug_optimizer().
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32596>
Borderlands 3 (both DX11 and DX12 renderers) have a common pattern
across many shaders:
con 32x4 %510 = (uint32)txf %2 (handle), %1191 (0x10) (coord), %1 (0x0) (lod), 0 (texture)
con 32x4 %512 = (uint32)txf %2 (handle), %1511 (0x11) (coord), %1 (0x0) (lod), 0 (texture)
...
con 32x4 %550 = (uint32)txf %2 (handle), %1549 (0x25) (coord), %1 (0x0) (lod), 0 (texture)
con 32x4 %552 = (uint32)txf %2 (handle), %1551 (0x26) (coord), %1 (0x0) (lod), 0 (texture)
A single basic block contains piles of texelFetches from a 1D buffer
texture, with constant coordinates. In most cases, only the .x channel
of the result is read. So we have something on the order of 28 sampler
messages, each asking for...a single uint32_t scalar value. Because our
sampler doesn't have any support for convergent block loads (like the
untyped LSC transpose messages for SSBOs)...this means we were emitting
SIMD8/16 (or SIMD16/32 on Xe2) sampler messages for every single scalar,
replicating what's effectively a SIMD1 value to the entire register.
This is hugely wasteful, both in terms of register pressure, and also in
back-and-forth sending and receiving memory messages.
The good news is we can take advantage of our explicit SIMD model to
handle this more efficiently. This patch adds a new optimization pass
that detects a series of SHADER_OPCODE_TXF_LOGICAL, in the same basic
block, with constant offsets, from the same texture. It constructs a
new divergent coordinate where each channel is one of the constants
(i.e <10, 11, 12, ..., 26> in the above example). It issues a new
NoMask divergent texel fetch which loads N useful channels in one go,
and replaces the rest with expansion MOVs that splat the SIMD1 result
back to the full SIMD width. (These get copy propagated away.)
We can pick the SIMD size of the load independently of the native shader
width as well. On Xe2, those 28 convergent loads become a single SIMD32
ld message. On earlier hardware, we use 2 SIMD16 messages. Or we can
use a smaller size when there aren't many to combine.
In fossil-db, this cuts 27% of send messages in affected shaders, 3-6%
of cycles, 2-3% of instructions, and 8-12% of live registers. On A770,
this improves performance of Borderlands 3 by roughly 2.5-3.5%.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32573>
This intrinsic was initially dedicated to mesh/task shaders, but the
mechanism it exposes also exists in the compute shaders on Gfx12.5+.
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31508>
The general idea is to be able to validate that certain instructions
were lowered and certain restrictions were already handled. Passes can
now assert their expectations, i.e. if a pass is mean to run after
certain lowerings or not.
The actual phases are a initial stab and as we re-organized the passes,
we may remove/add phases.
This commit just add some phase steps, later commits will make use of
them.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30496>
Add the `brw_` and `elk_` prefixes to the structs to avoid compilation
failure building with LTO ("violates the C++ One Definition Rule") when
the structs diverge.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30496>
We can achieve most of what brw_fs_opt_predicated_break() does with
simple peepholes at NIR -> BRW conversion time.
For predicated break and continue, we can simply look at an IF ... ENDIF
sequence after emitting it. If there's a single instruction between the
two, and it's a BREAK or CONTINUE, then we can move the predicate from
the IF onto the jump, and delete the IF/ENDIF. Because we haven't built
the CFG at this stage, we only need to remove them from the linked list
of instructions, which is trivial to do.
For the predicated while optimization, we can rely on the fact that we
already did the predicated break optimization, and simply look for a
predicated BREAK just before the WHILE. If so, we move the predicate
onto the WHILE, invert it, and remove the BREAK.
There are a few cases where this approach does a worse job than the old
one: nir_convert_from_ssa may introduce load_reg and store_reg in blocks
containing break, and nir_trivialize_registers may decide it needs to
insert movs into those blocks. So, at NIR -> BRW time, we'll actually
emit some MOVs there, which might have been possible to copy propagate
out after later optimizations.
However, the fossil-db results show that it's still pretty competitive.
For instructions, 1017 shaders were helped (average -1.87 instructions),
while only 62 were hurt (average +2.19 instructions). In affected
shaders, it was -0.08% for instructions.
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30498>
We don't actually need to extend g0's live range to the EOT message
generally - most messages that end a shader are headerless. The main
implicit use of g0 is for constructing scratch headers. With the last
two patches, we now consider scratch access that may exist in the IR
and already extend the liveness appropriately.
There is one remaining problem: spilling. The register allocator will
create new scratch messages when spilling a register, which need to
create scratch headers, which need g0. So, every new spill or fill
might extend the live range of g0, which would create new interference,
altering the graph. This can be problematic.
However, when compiling SIMD16 or SIMD32 fragment shaders, we don't
allow spilling anyway. So, why not use allow g0? Also, when trying
various scheduling modes, we first try allocation without spilling.
If it works, great, if not, we try a (hopefully) less aggressive
schedule, and only allow spilling on the lowest-pressure schedule.
So, even for regular SIMD8 shaders, we can potentially gain the use
of g0 on the first few tries at scheduling+allocation.
Once we try to allocate with spilling, we go back to reserving g0
for the entire program, so that we can construct scratch headers at
any point. We could possibly do better here, but this is simple and
reliable with some benefit.
Thanks to Ian Romanick for suggesting I try this approach.
fossil-db on Alchemist shows some more spill/fill improvements:
Totals:
Instrs: 149062395 -> 149053010 (-0.01%); split: -0.01%, +0.00%
Cycles: 12609496913 -> 12611652181 (+0.02%); split: -0.45%, +0.47%
Spill count: 52891 -> 52471 (-0.79%)
Fill count: 101599 -> 100818 (-0.77%)
Scratch Memory Size: 3292160 -> 3197952 (-2.86%)
Totals from 416541 (66.59% of 625484) affected shaders:
Instrs: 124058587 -> 124049202 (-0.01%); split: -0.01%, +0.01%
Cycles: 3567164271 -> 3569319539 (+0.06%); split: -1.61%, +1.67%
Spill count: 420 -> 0 (-inf%)
Fill count: 781 -> 0 (-inf%)
Scratch Memory Size: 94208 -> 0 (-inf%)
Witcher 3 shows a 33% reduction in scratch memory size, for example.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30319>
The generator code for emitting legacy scratch headers was implicitly
using g0 as a source. But the IR wasn't indicating any usage of g0,
which means the liveness isn't properly tracked at the IR level.
It works because we reserve g0 as permanently live for the whole
program. In order to stop doing that, we need to record it properly.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30319>
