VS, TCS, TES, and GS threads must end with a URB write message with the
EOT (end of thread) bit set. For VS and TES, we shadow output variables
with temporaries and perform all stores at the end of the shader, giving
us an existing message to do the EOT.
In tessellation control shaders, we don't defer output stores until the
end of the thread like we do for vertex or evaluation shaders. We just
process store_output and store_per_vertex_output intrinsics where they
occur, which may be in control flow. So we can't guarantee that there's
a URB write being at the end of the shader.
Traditionally, we've just emitted a separate URB write to finish TCS
threads, doing a writemasked write to an single patch header DWord.
On Broadwell, we need to set a "TR DS Cache Disable" bit, so this is
a convenient spot to do so. But on other platforms, there's no such
field, and this write is purely wasteful.
Insetad of emitting a separate write, we can just look for an existing
URB write at the end of the program and tag that with EOT, if possible.
We already had code to do this for geometry shaders, so just lift it
into a helper function and reuse it.
No changes in shader-db.
Reviewed-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/17944>
Move subgroup_id, that's only used by CS for verx10 < 125, as part of
the payload too -- even though is not, strictly speaking.
Note the thread execution of Task/Mesh is similar enough, so we make
their common struct inherit from cs_thread_payload.
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18176>
This backend lowering code has been dead since the removal of i965 -
nothing in the current source tree ever sets the flag.
This is handled by iris_setup_uniforms() and crocus_setup_uniforms().
Variable group size does not appear to be a feature in anv.
Reviewed-by: Marcin Ślusarz <marcin.slusarz@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18055>
This allows the software scoreboarding pass, scheduler, and so on
to handle the individual instructions and handle them, rather than
trusting in the generator to do scoreboarding correctly when expanding
the virtual instruction to multiple actual instructions.
By using SHADER_OPCODE_READ_SR_REG, we also correctly handle the
software scoreboarding workaround when reading DMask/VMask.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17530>
While we've taken advantage of split-sends in select situations, there
are many other cases (such as sampler messages, framebuffer writes, and
URB writes) that have never received that treatment, and continued to
use monolithic send payloads.
This commit introduces a new optimization pass which detects SEND
messages with a single payload, finds an adjacent LOAD_PAYLOAD that
produces that payload, splits it two, and updates the SEND to use both
of the new smaller payloads.
In places where we manually used split SENDS, we rely on underlying
knowledge of the message to determine a natural split point. For
example, header and data, or address and value.
In this pass, we instead infer a natural split point by looking at the
source registers. Often times, consecutive LOAD_PAYLOAD sources may
already be grouped together in a contiguous block, such as a texture
coordinate. Then, there is another bit of data, such as a LOD, that
may come from elsewhere. We look for the point where the source list
switches VGRFs, and split it there. (If there is a message header, we
choose to split there, as it will naturally come from elsewhere.)
This not only reduces the payload sizes, alleviating register pressure,
but it means that we may be able to eliminate some payload construction
altogether, if we have a contiguous block already and some extra data
being tacked on to one side or the other.
shader-db results for Icelake are:
total instructions in shared programs: 19602513 -> 19369255 (-1.19%)
instructions in affected programs: 6085404 -> 5852146 (-3.83%)
helped: 23650 / HURT: 15
helped stats (abs) min: 1 max: 1344 x̄: 9.87 x̃: 3
helped stats (rel) min: 0.03% max: 35.71% x̄: 3.78% x̃: 2.15%
HURT stats (abs) min: 1 max: 44 x̄: 7.20 x̃: 2
HURT stats (rel) min: 1.04% max: 20.00% x̄: 4.13% x̃: 2.00%
95% mean confidence interval for instructions value: -10.16 -9.55
95% mean confidence interval for instructions %-change: -3.84% -3.72%
Instructions are helped.
total cycles in shared programs: 848180368 -> 842208063 (-0.70%)
cycles in affected programs: 599931746 -> 593959441 (-1.00%)
helped: 22114 / HURT: 13053
helped stats (abs) min: 1 max: 482486 x̄: 580.94 x̃: 22
helped stats (rel) min: <.01% max: 78.92% x̄: 4.76% x̃: 0.75%
HURT stats (abs) min: 1 max: 94022 x̄: 526.67 x̃: 22
HURT stats (rel) min: <.01% max: 188.99% x̄: 4.52% x̃: 0.61%
95% mean confidence interval for cycles value: -222.87 -116.79
95% mean confidence interval for cycles %-change: -1.44% -1.20%
Cycles are helped.
total spills in shared programs: 8387 -> 6569 (-21.68%)
spills in affected programs: 5110 -> 3292 (-35.58%)
helped: 359 / HURT: 3
total fills in shared programs: 11833 -> 8218 (-30.55%)
fills in affected programs: 8635 -> 5020 (-41.86%)
helped: 358 / HURT: 3
LOST: 1 SIMD16 shader, 659 SIMD32 shaders
GAINED: 65 SIMD16 shaders, 959 SIMD32 shaders
Total CPU time (seconds): 1505.48 -> 1474.08 (-2.09%)
Examining these results: the few shaders where spills/fills increased
were already spilling significantly, and were only slightly hurt. The
applications affected were also helped in countless other shaders, and
other shaders stopped spilling altogether or had 50% reductions. Many
SIMD16 shaders were gained, and overall we gain more SIMD32, though many
close to the register pressure line go back and forth.
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17018>
Originally, we had virtual opcodes for scratch access, and let the
generator count spills/fills separately from other sends. Later, we
started using the generic SHADER_OPCODE_SEND for spills/fills on some
generations of hardware, and simply detected stateless messages there.
But then we started using stateless messages for other things:
- anv uses stateless messages for the buffer device address feature.
- nir_opt_large_constants generates stateless messages.
- XeHP curbe setup can generate stateless messages.
So counting stateless messages is not accurate. Instead, we move the
spill/fill accounting to the register allocator, as it generates such
things, as well as the load/store_scratch intrinsic handling, as those
are basically spill/fills, just at a higher level.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16691>
Now that we're being conservative in the pass, it's easy to tell when it
makes progress and we can put it in the OPT() macro. This way, we get
nice INTEL_DEBUG=optimizer dumps for it. While we're here, fix the
header comment which is massively out-of-date.
Reviewed-by: Emma Anholt <emma@anholt.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13734>
This rolls compute_sample_position into emit_samplepos_setup, its only
caller, by using a loop instead of calling it twice. We also
early-return for the !persample_dispatch case instead of doing it as
part of the sample calculation. This means that we don't call
fetch_payload_reg() to get sample_pos_reg unless we're actually going to
use it so the function is safe to call even if we haven't set up
sample_pos_reg. This will be important for the next commit.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14198>
Implement the output written by the task *workgroup* and available to
all the mesh *workgroups* dispatched from that task. We currently
ignore any layout annotations (since they are not really testable) and
produce a (packed) layout ourselves.
The URB messages are only SIMD8, so for larger SIMDs, the functions
will produce multiple messages. Making this lowering here instead of
the generic lower_simd_width() since it is not just a matter of
zip/unzip, e.g. the offset must be adjusted.
Indirect writes/reads are implemented by handling one component at a
time and using the PER_SLOT variant of the messages.
Note that VK_NV_mesh_shader allows reading outputs, so add support for
that as well.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13661>
Task/Mesh stages are CS-like stages, and include many
builtins (e.g. workgroup ID/index) and intrinsics (e.g. workgroup
memory primitives) originally present only in CS.
This commit add two new stages (task and mesh) that 'inherit' from CS
by embedding a brw_cs_prog_data in their own prog_data structure, so
that CS functionality can be easily reused. They also currently use
the same helpers to select the SIMD variant to use -- that was
recently added for CS.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13661>
In Fragment Shader, regular inputs are laid out in the thread payload
in a one dword per each half-GRF, that gives room for having the two
delta dwords needed for interpolation.
Per-primitive inputs are laid out before the regular inputs, and since
there's no need to have delta information, they are packed. So
half-GRF will be fully filled with 4 dwords of input.
When num_per_primitive_inputs is zero (the default case), behavior
should be the same as before.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13661>
Instead of depending on the driver to compile each resume shader
separately, we compile them all in one go in the back-end and build an
SBT as part of the shader program. Shader relocs are used to make the
entries in the SBT point point to the correct resume shader.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8637>
