The nir_intrinsic_load_simd_width_intel is always lowered by the
brw_nir_lower_simd() pass before the emission happens. This is likely
a "leftover" from patch rewriting/squashing that happened when this
intrinsic was added.
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5213>
Issue description from Matt's commit e7c376ad:
"var_range_end(v, n) loops over the n components of variable number v and
finds the maximum value, giving the last use of any component of v.
Therefore it expects v to correspond to the variable associated with the
.x channel of the VGRF.
var_from_reg() however returns the variable for the first channel of the
VGRF, post-swizzle.
So, if the last register had a swizzle with y, z, or w in the swizzle
component, we would read out of bounds. For any other register, we would
read liveness information from the next register.
The fix is to convert the src_reg to a dst_reg in order to call the
dst_reg version of var_from_reg() that doesn't consider the swizzle."
Closes: #3003
Fixes: 48dfb30f ('intel/compiler: Move all live interval analysis results into vec4_live_variables')
Reviewed-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Andrii Simiklit <asimiklit.work@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4941>
The motivating factor is: this lowering may cause
nir_intrinsic_load_local_group_size intrinsics to be added to the
shader, and by moving this around we make possible for the drivers to
lower that intrinsic by themselves.
Iris will do just that in a later patch for implementing variable
group size.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4794>
Intrinsic to get the SIMD width, which not always the same as subgroup
size. Starting with a small scope (Intel), but we can rename it later
to generalize if this turns out useful for other drivers.
Change brw_nir_lower_cs_intrinsics() to use this intrinsic instead of
a width will be passed as argument. The pass also used to optimized
load_subgroup_id for the case that the workgroup fitted into a single
thread (it will be constant zero). This optimization moved together
with lowering of the SIMD.
This is a preparation for letting the drivers call it before the
brw_compile_cs() step.
No shader-db changes in BDW, SKL, ICL and TGL.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4794>
gen12 does away with the single patch dispatch mode for tcs, and
increases some limits so that 8_patch mode can always work. Make the
necessary changes so we don't try to fall back to single patch mode.
Fixes KHR-GL46.tessellation_shader.single.max_patch_vertices and others
Fixes: 44754279ac ("intel/fs/gen12: Use TCS 8_PATCH mode.")
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4843>
The SFID field of the SHADER_OPCODE_MEMORY_FENCE and
SHADER_OPCODE_INTERLOCK instructions now indicates the target function
of the memory fence. Account the cycle-count cost to the right shared
unit.
Fixes: f858fa26b4 ("intel/fs,vec4: Pull stall logic for memory fences up into the IR")
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4817>
Shader-db results on ICL:
total instructions in shared programs: 17133088 -> 17133287 (<.01%)
instructions in affected programs: 61300 -> 61499 (0.32%)
helped: 0
HURT: 199
This means it's likely fixing 199 bugs. :-) All the changed shaders are
in Mad Max. It's surprisingly difficult to get the back-end compiler to
generate a pattern that hits this we don't tend to emit a lot coalescable
MOVs. The pattern in Mad Max that's able to hit is fsign(fsat(x)) under
the right conditions.
Closes: #2820
Cc: mesa-stable@lists.freedesktop.org
Tested-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4773>
In Gen11+, when emitting a fence for both L3 and SLM, the generated
code would look like
SEND, MOV (for stall), SEND, MOV (for stall)
This commit change that so two SENDs are emitted before the MOVs for
stall. This is similar to the approach used in Ivy Bridge for the
render fence.
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3278>
Instead of emitting the stall MOV "inside" the
SHADER_OPCODE_MEMORY_FENCE generation, use the scheduling fences when
creating the IR.
For IvyBridge, every (data cache) fence is accompained by a render
cache fence, that now is explicit in the IR, two
SHADER_OPCODE_MEMORY_FENCEs are emitted (with different SFIDs).
Because Begin and End interlock intrinsics are effectively memory
barriers, move its handling alongside the other memory barrier
intrinsics. The SHADER_OPCODE_INTERLOCK is still used to distinguish
if we are going to use a SENDC (for Begin) or regular SEND (for End).
This change is a preparation to allow emitting both SENDs in Gen11+
before we can stall on them.
Shader-db results for IVB (i965):
total instructions in shared programs: 11971190 -> 11971200 (<.01%)
instructions in affected programs: 11482 -> 11492 (0.09%)
helped: 0
HURT: 8
HURT stats (abs) min: 1 max: 3 x̄: 1.25 x̃: 1
HURT stats (rel) min: 0.03% max: 0.50% x̄: 0.14% x̃: 0.10%
95% mean confidence interval for instructions value: 0.66 1.84
95% mean confidence interval for instructions %-change: 0.01% 0.27%
Instructions are HURT.
Unlike the previous code, that used the `mov g1 g2` trick to force
both `g1` and `g2` to stall, the scheduling fence will generate `mov
null g1` and `mov null g2`. During review it was decided it was not
worth keeping the special codepath for the small effect will have.
Shader-db results for HSW (i965), BDW and SKL don't have a change
on instruction count, but do report changes in cycles count, showing
SKL results below
total cycles in shared programs: 341738444 -> 341710570 (<.01%)
cycles in affected programs: 7240002 -> 7212128 (-0.38%)
helped: 46
HURT: 5
helped stats (abs) min: 14 max: 1940 x̄: 676.22 x̃: 154
helped stats (rel) min: <.01% max: 2.62% x̄: 1.28% x̃: 0.95%
HURT stats (abs) min: 2 max: 1768 x̄: 646.40 x̃: 362
HURT stats (rel) min: <.01% max: 0.83% x̄: 0.28% x̃: 0.08%
95% mean confidence interval for cycles value: -777.71 -315.38
95% mean confidence interval for cycles %-change: -1.42% -0.83%
Cycles are helped.
This seems to be the effect of allocating two registers separatedly
instead of a single one with size 2, which causes different register
allocation, affecting the cycle estimates.
while ICL also has not change on instruction count but report changes
negative changes in cycles
total cycles in shared programs: 352665369 -> 352707484 (0.01%)
cycles in affected programs: 9608288 -> 9650403 (0.44%)
helped: 4
HURT: 104
helped stats (abs) min: 24 max: 128 x̄: 88.50 x̃: 101
helped stats (rel) min: <.01% max: 0.85% x̄: 0.46% x̃: 0.49%
HURT stats (abs) min: 2 max: 2016 x̄: 408.36 x̃: 48
HURT stats (rel) min: <.01% max: 3.31% x̄: 0.88% x̃: 0.45%
95% mean confidence interval for cycles value: 256.67 523.24
95% mean confidence interval for cycles %-change: 0.63% 1.03%
Cycles are HURT.
AFAICT this is the result of the case above.
Shader-db results for TGL have similar cycles result as ICL, but also
affect instructions
total instructions in shared programs: 17690586 -> 17690597 (<.01%)
instructions in affected programs: 64617 -> 64628 (0.02%)
helped: 55
HURT: 32
helped stats (abs) min: 1 max: 16 x̄: 4.13 x̃: 3
helped stats (rel) min: 0.05% max: 2.78% x̄: 0.86% x̃: 0.74%
HURT stats (abs) min: 1 max: 65 x̄: 7.44 x̃: 2
HURT stats (rel) min: 0.05% max: 4.58% x̄: 1.13% x̃: 0.69%
95% mean confidence interval for instructions value: -2.03 2.28
95% mean confidence interval for instructions %-change: -0.41% 0.15%
Inconclusive result (value mean confidence interval includes 0).
Now that more is done in the IR, more dependencies are visible and
more SWSB annotations are emitted. Mixed with different register
allocation decisions like above, some shaders will see more `sync
nops` while others able to avoid them.
Most of the new `sync nops` are also redundant and could be dropped,
which will be fixed in a separate change.
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3278>
The cycle count estimation logic part of the scheduler is now
redundant with the shader performance modeling pass, and the estimates
can be consolidated into the brw::performance analysis result object
instead of being part of the CFG, which guarantees that the estimates
cannot be accessed without previously calling the
performance_analysis::require() method, which makes sure that the
right analysis pass is executed at the right time if we don't already
have up-to-date cached results.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
So we can eventually remove the cycle count estimates from the CFG
data structure and consolidate performance information in the
brw::performance object.
It would be cleaner to pass the brw::performance object directly to
the disassembler but that isn't straightforward since the disassembler
is built as a plain C file unlike the rest of the compiler back-end.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
These should be more accurate than the current cycle counts, since
among other things they consider the effect of post-scheduling passes
like the software scoreboard on TGL. In addition it will enable us to
clean up some of the now redundant cycle-count estimation
functionality in the instruction scheduler.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This is useful in order to identify codegen issues caused by SIMD32.
It doesn't currently have any effect on compute shaders since SIMD32
dispatch is only enabled for CS when it's strictly necessary to do so
in order to support the workgroup size requested for the shader --
That might change in the future though when we hook up the SIMD32
heuristic to CS compilation.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
The heuristic enables the SIMD32 fragment shader based on whether the
IR performance modeling pass predicts it to have greater throughput
than the SIMD16 and SIMD8 variants of the same shader. It would be
straightforward to do the same thing in order to control whether
SIMD16 dispatch is enabled, but it's pending additional performance
evaluation.
The INTEL_DEBUG=do32 option is left around in order to force the
SIMD32 shader to be used regardless of the result of the heuristic,
since it's useful as a debugging aid e.g. in order to identify
SIMD32-specific codegen issues which may be masked by the SIMD32
heuristic, or cases where the heuristic is incorrectly disabling
SIMD32 shaders that offer a performance advantage.
Currently this is only enabled on Gen6+, since SIMD32 codegen support
is incomplete on earlier platforms.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This makes brw_compile_fs() look a bit more similar to
brw_compile_cs(). It saves us three v*_shader_stats local variables,
and will save us additional triplicated declarations as we start
tracking IR performance analysis results.
The triplicated cfg pointers are left around because they're set to
NULL to mark specific dispatch modes as disabled (e.g. in order to
enforce hardware restrictions). Doing the same thing with the visitor
pointers would cause data leaks.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This introduces an analysis pass intended to estimate several
performance statistics of the shader, including cycle count latency
and throughput values, based on static modeling. It has instruction
performance information more comprehensive than the current scheduling
pass for all platforms between Gen4-11, and works on both the FS and
VEC4 back-end.
The most immediate purpose of this pass is to implement a heuristic
meant to determine whether using SIMD32 dispatch for a fragment shader
can be expected to help more than it hurts. In addition this will
allow the effect of passes run after scheduling (e.g. the TGL software
scoreboard pass and the VEC4 dependency control pass) to be visible in
shader-db statistics.
But that isn't the end of the story, other potential applications of
this pass (not part of this MR) I've been playing around with are:
- Implement a similar SIMD16 heuristic allowing the identification of
inefficient SIMD16 fragment shaders.
- Implement similar SIMD16 and SIMD32 heuristics for the compute
shader stage -- Currently compute shader builds always use the
SIMD16 shader if available and never use the SIMD32 shader unless
strictly necessary, which is suboptimal under certain conditions.
- Hook up to the instruction scheduler in order to improve the
accuracy of its timing information.
- Use as heuristic in order to drive the selection of scheduling
modes (Matt was experimenting with that).
- Plug to the TGL software scoreboard pass in order to implement a
more effective SBID token allocation algorithm, since in general
the optimal token allocation depends on the timings of all
instructions in the program.
- Use its bottleneck detection functionality in order to implement a
heuristic computing a more optimal bound for the number of fragment
shader threads executed in parallel (by adjusting the
MaximumNumberofThreadsPerPSD control of 3DSTATE_PS).
As a follow-up I'm planning to submit updated timing information for
Gen12 platforms -- Everything else required to support Gen12 like SWSB
handling is already included in this patch, but there were some IP
concerns regarding the TGL timing parameters since they cannot
currently be obtained with the documentation and hardware which is
publicly available. The timing parameters for any previous Gen7-11
platforms can be obtained by anyone by sampling the timestamp register
using e.g. shader_time, though I have some more convenient
instrumentation coming up.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Makes more sense considering SIMD32. Relaxing the assertion in
brw_ir_fs.h will be required in order to avoid assertion failures on
SNB with SIMD32 fragment shaders.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
In Gen12 the Poly 0 Info DWORD containing the Viewport Index and
Render Target Index fields were moved from r0.0 to r1.1 in order to
make room for dual-polygon dispatch. The render target message format
was updated to expect that information in the same location, so we
didn't need to make any changes for framebuffer fetch to work with
SIMD8 and SIMD16 dispatch. Unfortunately that won't work with SIMD32,
since the render target message header is assembled from r0 and r2
instead of r1, and the r2 thread payload wasn't updated with an
additional copy of the same information. We need to fix things up
manually instead. This avoids a handful of
EXT_shader_framebuffer_fetch regressions in combination with SIMD32
fragment shaders.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This applies the same work-around I commited as b84fa0b31e
"intel/fs/gen11: Work around dual-source blending hangs in combination
with SIMD32." to Gen12, which seems to suffer from the same hardware
bug found empirically. The failure mode seems to be identical.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
The Gen12 docs are rather contradictory regarding the dispatch
configurations supported by the fragment shader -- The same table
present in previous generations seems to imply that only one dispatch
mode can be enabled when doing per-sample shading, but a restriction
documented in the 3DSTATE_PS_BODY page implies the opposite: That
SIMD32 can only be used in combination with some other dispatch mode.
The latter seems to match the behavior of real hardware as I could
tell from my testing: A bunch of multisample test-cases that do
per-sample shading hang if we only provide a SIMD32 shader.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
VEC4_OPCODE_PICK_HIGH_32BIT performs 32-bit UD access on a 64-bit DF
value. abs and negate make sense on DF, but break entirely when
trying to access pieces of the value as unsigned integer dwords.
Fixes an fsign Piglit test on Ivybridge:
tests/spec/arb_gpu_shader_fp64/execution/built-in-functions/vs-sign-neg-abs
It had regressed when I removed nir_lower_to_source_modifiers, as that
caused us to start generating different code which provoked this bug.
Fixes: b7c47c4f7c ("intel/compiler: Drop nir_lower_to_source_mods() and related handling.")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/2817
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4691>
I think we're unanimous in wanting to drop nir_lower_to_source_mods.
It's a bit of complexity to handle in the backend, but perhaps more
importantly, would be even more complexity to handle in nir_search.
And, it turns out that since we made other compiler improvements in the
last few years, they no longer appear to buy us anything of value.
Summarizing the results from shader-db from this patch:
- Icelake (scalar mode)
Instruction counts:
- 411 helped, 598 hurt (out of 139,470 shaders)
- 99.2% of shaders remain unaffected. The average increase in
instruction count in hurt programs is 1.78 instructions.
- total instructions in shared programs: 17214951 -> 17215206 (<.01%)
- instructions in affected programs: 1143879 -> 1144134 (0.02%)
Cycles:
- 1042 helped, 1357 hurt
- total cycles in shared programs: 365613294 -> 365882263 (0.07%)
- cycles in affected programs: 138155497 -> 138424466 (0.19%)
- Haswell (both scalar and vector modes)
Instruction counts:
- 73 helped, 1680 hurt (out of 139,470 shaders)
- 98.7% of shaders remain unaffected. The average increase in
instruction count in hurt programs is 1.9 instructions.
- total instructions in shared programs: 14199527 -> 14202262 (0.02%)
- instructions in affected programs: 446499 -> 449234 (0.61%)
Cycles:
- 5253 helped, 5559 hurt
- total cycles in shared programs: 359996545 -> 360038731 (0.01%)
- cycles in affected programs: 155897127 -> 155939313 (0.03%)
Given that ~99% of shader-db remains unaffected, and the affected
programs are hurt by about 1-2 instructions - which are all cheap
ALU instructions - this is unlikely to be measurable in terms of
any real performance impact that would affect users.
So, drop them and simplify the backend, and hopefully enable other
future simplifications in NIR.
Reviewed-by: Eric Anholt <eric@anholt.net> [v1]
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4616>
Consider the following case:
// g119-123 are written somewhere above
mul.sat(16) g67<1>F g6.4<0,1,0>F g125<8,8,1>F
mul.sat(16) g69<1>F g6.5<0,1,0>F g125<8,8,1>F
mul.sat(16) g71<1>F g6.6<0,1,0>F g125<8,8,1>F
mov(16) g119<1>F g67<8,8,1>F
mov(16) g121<1>F g69<8,8,1>F
mov(16) g123<1>F g71<8,8,1>F
We should be able to coalesce it into
mul.sat(16) g119<1>F g6.4<0,1,0>F g125<8,8,1>F
mul.sat(16) g121<1>F g6.5<0,1,0>F g125<8,8,1>F
mul.sat(16) g123<1>F g6.6<0,1,0>F g125<8,8,1>F
What's stopping us is an overly conservative check for writes to the two
registers being coalesced. The check walks over the intersection of
their live ranges and checks for no writes to either one. However,
because the register which starts the live range (the mul.sat in this
case) is inside that intersection, we flag it as a write in the
intersection and don't coalesce. However, this case is safe because the
destination register of the copy is never read after the source is
written.
Shader-db changes on ICL:
total instructions in shared programs: 16043613 -> 16042610 (<.01%)
instructions in affected programs: 43036 -> 42033 (-2.33%)
helped: 226
HURT: 0
helped stats (abs) min: 1 max: 30 x̄: 4.44 x̃: 4
helped stats (rel) min: 0.09% max: 26.67% x̄: 4.89% x̃: 3.43%
95% mean confidence interval for instructions value: -4.86 -4.02
95% mean confidence interval for instructions %-change: -5.57% -4.22%
Instructions are helped.
total cycles in shared programs: 334766372 -> 334710124 (-0.02%)
cycles in affected programs: 617548 -> 561300 (-9.11%)
helped: 214
HURT: 2
helped stats (abs) min: 15 max: 1512 x̄: 263.21 x̃: 212
helped stats (rel) min: 0.30% max: 75.36% x̄: 25.30% x̃: 21.58%
HURT stats (abs) min: 40 max: 40 x̄: 40.00 x̃: 40
HURT stats (rel) min: 0.15% max: 0.15% x̄: 0.15% x̃: 0.15%
95% mean confidence interval for cycles value: -277.91 -242.90
95% mean confidence interval for cycles %-change: -27.58% -22.55%
Cycles are helped.
No spill/fill changes or gained/lost
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4627>
Change brw_memory_fence to return the number of messages emitted, and
use that to update the send_count statistic in code generation.
This will fix the book-keeping for IVB since the memory fences will
result in two SEND messages.
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4646>
The versions that take a specific number of operands will do various
fixups depending on the platform and the opcode. However, the version
that takes an array of sources did not. This makes all version operate
similarly.
Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4582>
