From "Alpha Coverage" section of SKL PRM Volume 7:
"If Pixel Shader outputs oMask, AlphaToCoverage is disabled in
hardware, regardless of the state setting for this feature."
From OpenGL spec 4.6, "15.2 Shader Execution":
"The built-in integer array gl_SampleMask can be used to change
the sample coverage for a fragment from within the shader."
From OpenGL spec 4.6, "17.3.1 Alpha To Coverage":
"If SAMPLE_ALPHA_TO_COVERAGE is enabled, a temporary coverage value
is generated where each bit is determined by the alpha value at the
corresponding sample location. The temporary coverage value is then
ANDed with the fragment coverage value to generate a new fragment
coverage value."
Similar wording could be found in Vulkan spec 1.1.100
"25.6. Multisample Coverage"
Thus we need to compute alpha to coverage dithering manually in shader
and replace sample mask store with the bitwise-AND of sample mask and
alpha to coverage dithering.
The following formula is used to compute final sample mask:
m = int(16.0 * clamp(src0_alpha, 0.0, 1.0))
dither_mask = 0x1111 * ((0xfea80 >> (m & ~3)) & 0xf) |
0x0808 * (m & 2) | 0x0100 * (m & 1)
sample_mask = sample_mask & dither_mask
Credits to Francisco Jerez <currojerez@riseup.net> for creating it.
It gives a number of ones proportional to the alpha for 2, 4, 8 or 16
least significant bits of the result.
GEN6 hardware does not have issue with simultaneous usage of sample mask
and alpha to coverage however due to the wrong sending order of oMask
and src0_alpha it is still affected by it.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109743
Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Other places will need to do this soon to properly handle source
swizzles. The patch looks a little odd, but the change is pretty
straight forward. All of the swizzle and mask handling is moved out,
but the code for handling move instructions and vecN instructions
remains in nir_emit_alu.
I'm not terribly pleased with the "need_dest" parameter, but
get_nir_dest is (somewhat surprisingly) destructive. I am open to
suggestions of alternatives.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
The next patch replaces an unsigned bitfield with a plain unsigned,
which triggers gcc to begin warning on signed/unsigned comparisons.
Keeping this patch separate from the actual move allows bisectablity and
generates no additional warnings temporarily.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
These are broken on a future platform, but it turns out we don't need
to fix them, since they're just type-converting moves with strided
source. Kill them.
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
This legalization pass is meant to handle situations where the source
or destination regioning controls of an instruction are unsupported by
the hardware and need to be lowered away into separate instructions.
This should be more reliable and future-proof than the current
approach of handling CHV/BXT restrictions manually all over the
visitor. The same mechanism is leveraged to lower unsupported type
conversions easily, which obsoletes the lower_conversions pass.
v2: Give conditional modifiers the same treatment as predicates for
SEL instructions in lower_dst_modifiers() (Iago). Special-case a
couple of other instructions with inconsistent conditional mod
semantics in lower_dst_modifiers() (Curro).
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Align16 is no longer a thing, so a new implementation is provided
using Align1 instead. Not all possible swizzles can be represented as
a single Align1 region, but some fast paths are provided for
frequently used swizzles that can be represented efficiently in Align1
mode.
Fixes ~90 subgroup quad swap Vulkan CTS tests.
Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
lower_integer_multiplication() implements 32x32-bit multiplication on
some platforms by bit-casting one of the 32-bit sources into two
16-bit unsigned integer portions. This can give incorrect results if
the original instruction specified a source modifier. Fix it by
emitting an additional MOV instruction implementing the source
modifiers where necessary.
Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Everywhere we handle SSBO intrinsics, we have exactly the same pattern
for computing the index so we may as well make a helper for it. We also
add a get_nir_src_imm to vec4 and use it for SSBO offsets.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Previously, the back-end compiler turn image access into magic uniform
reads and there was a complex contract between back-end compiler and
driver about setting up and filling out those params. As of this
commit, both drivers now lower image_deref_load_param_intel intrinsics
to load_uniform intrinsics controlled by the driver and lower the other
image_deref_* intrinsics to image_* intrinsics which take an actual
binding table index. There are still "magic" uniforms but they are now
added and controlled entirely by the driver and that contract no longer
spans components.
This also has the side-effect of making most image use compile-time
binding table indices. Previously, all image access pulled the binding
table index from a uniform. Part of the reason for this was that the
magic uniforms made it difficult to decouple binding table indices from
the uniforms and, since they are indexed completely differently
(especially in Vulkan), it was hard to pull them apart. Now that the
driver is handling both, it's trivial to decouple the two and provide
actual binding table indices.
Shader-db results on Kaby Lake:
total instructions in shared programs: 15166872 -> 15164293 (-0.02%)
instructions in affected programs: 115834 -> 113255 (-2.23%)
helped: 191
HURT: 0
total cycles in shared programs: 571311495 -> 571196465 (-0.02%)
cycles in affected programs: 4757115 -> 4642085 (-2.42%)
helped: 73
HURT: 67
total spills in shared programs: 10951 -> 10926 (-0.23%)
spills in affected programs: 742 -> 717 (-3.37%)
helped: 7
HURT: 0
total fills in shared programs: 22226 -> 22201 (-0.11%)
fills in affected programs: 1146 -> 1121 (-2.18%)
helped: 7
HURT: 0
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
v2: Split changes to the message type field to another patch. Suggested
by Caio.
Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
The hardware doesn't support byte immediates, so similar to setup_imm_df()
for doubles, these helpers work by loading the constant value into a
VGRF.
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
And handle 32-wide payload register reads in fetch_payload_reg().
v2 (Jason Ekstrand);
- Fix some whitespace and brace placement
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Since we had to rewrite the deref walking loop anyway, I took the
opportunity to make it a bit clearer and more efficient. In particular,
in the AoA case, we will now emit one minmax instead of one per array
level.
Acked-by: Rob Clark <robdclark@gmail.com>
Acked-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Acked-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
These new shuffle functions deal with the shuffle/unshuffle operations
needed for read/write operations using 32-bit components when the
read/written components have a different bit-size (8, 16, 64-bits).
Shuffle from 32-bit to 32-bit becomes a simple MOV.
shuffle_src_to_dst takes care of doing a shuffle when source type is
smaller than destination type and an unshuffle when source type is
bigger than destination. So this new read/write functions just need
to call shuffle_src_to_dst assuming that writes use a 32-bit
destination and reads use a 32-bit source.
As shuffle_for_32bit_write/from_32bit_read components take components
in unit of source/destination types and shuffle_src_to_dst takes units
of the smallest type component, we adjust components and first_component
parameters.
To enable this new functions it is needed than there is no
source/destination overlap in the case of shuffle_from_32bit_read.
That never happens on shuffle_for_32bit_write as it allocates a new
destination register as it was at shuffle_64bit_data_for_32bit_write.
v2: Reword commit log and add comments to explain why first_component
and components parameters are adjusted. (Jason Ekstrand)
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
This replaces the special magic opcodes which implicitly read inputs
with explicit use of the ATTR file.
v2 (Jason Ekstrand):
- Break into multiple patches
- Change the units of the FS ATTR to be in logical scalars
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Matt Turner <mattst88@gmail.com>
These days, we're just passing a pointer to a prog_data field, which
we already have access to. We can just use it directly.
(In the past, it was a pointer to a separate value.)
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
This helper used to load 16bit components from 32-bits read now allows
skipping components with the new parameter first_component. The semantics
now skip components until we reach the first_component, and then reads the
number of components passed to the function.
All previous uses of the helper are updated to use 0 as first_component.
This will allow read 16-bit components when the first one is not aligned
32-bit. Enabling more usages of untyped_reads with 16-bit types.
v2: (Jason Ektrand)
Change parameters order to first_component, num_components
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
In a future patch, generate_ddy will want to inspect inst->exec_size.
Change generate_ddx as well for consistency.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
If multiple instructions are emitted, special handling of things like
conditional mod and NoDDClr/NoDDChk need to be performed.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This should allow the post-RA scheduler to do a slightly better job at
hiding latency in presence of instructions incurring bank conflicts.
The main purpuse of this patch is not to improve performance though,
but to get conflict cycles to show up in shader-db statistics in order
to make sure that regressions in the bank conflict mitigation pass
don't go unnoticed.
Acked-by: Matt Turner <mattst88@gmail.com>
Unnecessary GRF bank conflicts increase the issue time of ternary
instructions (the overwhelmingly most common of which is MAD) by
roughly 50%, leading to reduced ALU throughput. This pass attempts to
minimize the number of bank conflicts by rearranging the layout of the
GRF space post-register allocation. It's in general not possible to
eliminate all of them without introducing extra copies, which are
typically more expensive than the bank conflict itself.
In a shader-db run on SKL this helps roughly 46k shaders:
total conflicts in shared programs: 1008981 -> 600461 (-40.49%)
conflicts in affected programs: 816222 -> 407702 (-50.05%)
helped: 46234
HURT: 72
The running time of shader-db itself on SKL seems to be increased by
roughly 2.52%±1.13% with n=20 due to the additional work done by the
compiler back-end.
On earlier generations the pass is somewhat less effective in relative
terms because the hardware incurs a bank conflict anytime the last two
sources of the instruction are duplicate (e.g. while trying to square
a value using MAD), which is impossible to avoid without introducing
copies. E.g. for a shader-db run on SNB:
total conflicts in shared programs: 944636 -> 623185 (-34.03%)
conflicts in affected programs: 853258 -> 531807 (-37.67%)
helped: 31052
HURT: 19
And on BDW:
total conflicts in shared programs: 1418393 -> 987539 (-30.38%)
conflicts in affected programs: 1179787 -> 748933 (-36.52%)
helped: 47592
HURT: 70
On SKL GT4e this improves performance of GpuTest Volplosion by 3.64%
±0.33% with n=16.
NOTE: This patch intentionally disregards some i965 coding conventions
for the sake of reviewability. This is addressed by the next
squash patch which introduces an amount of (for the most part
boring) boilerplate that might distract reviewers from the
non-trivial algorithmic details of the pass.
The following patch is squashed in:
SQUASH: intel/fs/bank_conflicts: Roll back to the nineties.
Acked-by: Matt Turner <mattst88@gmail.com>
This helpers are used to load/store 16-bit types from/to 32-bit
components.
The functions shuffle_32bit_load_result_to_16bit_data and
shuffle_16bit_data_for_32bit_write are implemented in a similar
way than the analogous functions for handling 64-bit types.
v1: Explain need of temporary in shuffle operations. (Jason Ekstrand)
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Although from SPIR-V point of view, rounding modes are attached to the
operation/destination, on i965 it is a status, so we don't need to
explicitly set the rounding mode if the one we want is already set.
Taking into account that the default mode is RTE, one possible
optimization would be optimize out the first RTE set for each
block. For in order to work, we would need to take into account block
interrelationships. At this point, it is not worth to complicate the
optimization for such small gain.
v2: Use a single SHADER_OPCODE_RND_MODE opcode taking an immediate
with the rounding mode (Curro)
v3: Reset optimization for every block. (Jason Ekstrand)
Signed-off-by: Jose Maria Casanova Crespo <jmcasanova@igalia.com>
Signed-off-by: Alejandro Piñeiro <apinheiro@igalia.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
We're going to want subgroup ID for SPIR-V subgroups eventually anyway.
We really only want to push one and calculate the other from it. It
makes a bit more sense to push the subgroup ID because it's simpler to
calculate and because it's a real API thing. The only advantage to
pushing the base thread ID is to avoid a single SHL in the shader.
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Previously, brw_nir_lower_intrinsics added the param and then emitted a
load_uniform intrinsic to load it directly. This commit switches things
over to use a specific NIR intrinsic for the thread id. The one thing I
don't like about this approach is that we have to copy thread_local_id
over to the new visitor in import_uniforms.
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
It's 8 for everything except compute shaders. For compute shaders,
there's no need to duplicate the computation and it's just a possible
source of error.
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
All callers of this function allocate a fs_reg expressly to pass into
it. It's much easier if we just let the helper allocate the register.
While we're here, we switch it to doing the MOVs with an integer type so
that we don't accidentally canonicalize floats on half of a double.
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
This moves us away to the array of pointers model and onto a model where
each param is represented by a generic uint32_t handle. We reserve 2^16
of these handles for builtins that get generated by somewhere inside the
compiler and have well-defined meanings. Generic params have handles
whose meanings are defined by the driver.
The primary downside to this new approach is that it moves a little bit
of the work that we would normally do at compile time to draw time. On
my laptop this hurts OglBatch6 by no more than 1% and doesn't seem to
have any measurable affect on OglBatch7. So, while this may come back
to bite us, it doesn't look too bad.
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This actually takes advantage of the newly pushed UBO data, avoiding
pull loads.
Improves performance in GLBenchmark Manhattan 3.1 by:
HSW: ~1%, BDW/SKL/KBL GT2: 3-4%, SKL GT4: 7-8%, APL: 4-5%.
(thanks to Eero Tamminen for these numbers)
shader-db results on Skylake, ignoring programs with spill/fill changes:
total instructions in shared programs: 13963994 -> 13651893 (-2.24%)
instructions in affected programs: 4250328 -> 3938227 (-7.34%)
helped: 28527
HURT: 0
total cycles in shared programs: 179808608 -> 172535170 (-4.05%)
cycles in affected programs: 79720410 -> 72446972 (-9.12%)
helped: 26951
HURT: 1248
LOST: 46
GAINED: 21
Many "Deus Ex: Mankind Divided" shaders which already spilled end up
spill a lot more (about 240 programs hurt, 9 helped). The cycle
estimator suggests this is still overall a win (-0.23% in cycle counts)
presumably because we trade pull loads for fills.
v2: Drop "PULL" environment variable left in for initial debugging
(caught by Matt).
Reviewed-by: Matt Turner <mattst88@gmail.com>
With UBOs, the answer of "have we decided to push this uniform" gets
a bit more complicated - for one, we have multiple surfaces. This
patch refactors things so we can add the new code in a single place.
Reviewed-by: Matt Turner <mattst88@gmail.com>
NIR calls these system values but they come in from the VF unit as
vertex data. It's terribly convenient to just be able to treat them as
such in the back-end.
Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
