In general, sinking ALU instructions can negatively impact register pressure,
since it extends the live ranges of the sources, although it does shrink the live range
of the destination.
However, constants do not usually contribute to register pressure. This is not a
totally true assumption, but it's pretty good in practice, since...
* constants can be rematerialized (backend-dependent)
* constants can often be inlined (ISA-dependent)
* constants can sometimes be promoted to free uniform registers (ISA-dependent)
* constants can live in scalar registers although the ALU destination might need
a vector register (and vector registers are assumed to be much more expensive
than scalar registers, again ISA-dependent)
So, assume that constants have zero effect on register pressure. Now consider an
ALU instruction where all but one source is a constant. Then there are two
cases:
1. The ALU instruction is moved past when its source was otherwise killed. Then
there is no effect on register pressure, since the source live range is
extended exactly as much as the destination live range shrinks.
2. The ALU instruction is moved down but its source is still alive where it's
moved to. Then register pressure is improved, since the source live range is
unchanged while the destination live range shrinks.
So, as a heuristic, we always move ALU instructions where n-1 sources are
constant. As an inevitable special case, this also (necessarily) moves unary ALU
ops, which should be beneficial by the same justification. This is not 100%
perfect but it is well-motivated. Results on AGX are decent:
total instructions in shared programs: 1796101 -> 1795652 (-0.02%)
instructions in affected programs: 326822 -> 326373 (-0.14%)
helped: 800
HURT: 371
Inconclusive result (%-change mean confidence interval includes 0).
total bytes in shared programs: 11805004 -> 11801424 (-0.03%)
bytes in affected programs: 2610630 -> 2607050 (-0.14%)
helped: 912
HURT: 462
Inconclusive result (%-change mean confidence interval includes 0).
total halfregs in shared programs: 525818 -> 515399 (-1.98%)
halfregs in affected programs: 118197 -> 107778 (-8.81%)
helped: 2095
HURT: 804
Halfregs are helped.
total threads in shared programs: 18916608 -> 18917056 (<.01%)
threads in affected programs: 4800 -> 5248 (9.33%)
helped: 7
HURT: 0
Threads are helped.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24833>
Redefine in terms of the algebraic property. This correctly handles the
Mali-specific derivatives.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24833>
Avoid code duplication because it need to be used in following commits
Fixes: 1a8dd84ec6 ("nir: Propagate the type sampler type change to the used variable.")
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Signed-off-by: Illia Polishchuk <illia.a.polishchuk@globallogic.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25145>
This adds a driver control to instruct NIR to not inline
all functions.
It adds a very simple inlining heuristic that works for
what I've played with, but will probably need to grow some
better ideas.
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24687>
Many shaders issue full memory barriers, which may need to synchronize
access to images, SSBOs, shared local memory, or global memory.
However, many of them only use a subset of those memory types - say,
only SSBOs.
Shaders may also have patterns such as:
1. shared local memory access
2. barrier with full variable modes
3. more shared local memory access
4. image access
In this case, the barrier is needed to ensure synchronization between
the various shared memory operations. Image reads and writes do also
exist, but they are all on one side of the barrier, so it is a no-op for
image access. We can drop the image mode from the barrier here too.
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24842>
These are common enough to merit their own helpers.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24910>
nir_const_value variables in nir_const_value_for_int and
nor_const_value_for_uint are unused resulting in unnecessary dead code.
The unused-variable warning has been suppressed by the memset following
their declarations.
Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24851>
Passes dEQP-VK.spirv_assembly.*opquantize*.
Unlike the DXIL lowering, this should correctly handle NaNs. (I belive Dozen has
a bug here that is masked by running constant folding early and poor CTS
coverage.) It is also faster than the DXIL lowering for hardware that supports
f2f16 conversions natively. It is not as good as a backend implementation that
could flush-to-zero in hardware... but for a debug instruction it should be more
than good enough.
It might be slightly better to multiply with 0.0 to get the appropriate zero,
but NIR really likes optimizing that out ...
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24616>
There are two new variable modes:
- nir_var_mem_node_payload
- nir_var_mem_node_payload_in
Also add a few more intrinsics and some shader info.
Reviewed-by: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24512>
This helper exists for a very tiny set of use-cases but it's better to
have the helper live in nir.c than hand-roll it elsewhere.
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24729>
Currently SPIR-V does pull all the NIR constants it creates into the
first block, but we plan to change that behavior to let those constants
be defined as they are used.
This pass was written to provide a fallback to the old behavior, it will
be used for radv to avoid regressions when performing the SPIR-V change.
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5282>
The nir_op_is_vec() helper I added in 842338e2f0 ("nir: Add a
nir_op_is_vec helper") treats nir_op_mov as a vec even though the
semanitcs of the two are different. In retrospect, this was a mistake
as the previous three fixup commits show. This commit splits the helper
into two: nir_op_is_vec() and nir_op_is_vec_or_mov() and uses the
appropriate helper at each call site. Hopefully, this rename will
encurage any future users of these helpers to think about nir_op_mov as
separate from nir_op_vecN and we can avoid these bugs.
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24704>
Generated mostly with sed:
sed -i -e 's/live_ssa_def/live_def/g' src/compiler/nir/nir.h src/compiler/nir/*.c
Plus three fixups in various Intel drivers.
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24703>
We already renamed the type, we just need to rename the enum and the
casting helper functions.
Generated with sed:
sed -i -e 's/nir_instr_type_ssa_undef/nir_instr_type_undef/g' src/**/*.h src/**/*.c src/**/*.cpp
sed -i -e 's/nir_instr_as_ssa_undef/nir_instr_as_undef/g' src/**/*.h src/**/*.c src/**/*.cpp
and two tiny whitespace fixups in lima.
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24703>
Instead, we replace every use of it with nir_def. Most of this commit
was generated by sed:
sed -i -e 's/dest.ssa/def/g' src/**/*.h src/**/*.c src/**/*.cpp
A few manual fixups were required in lima and the nir_legacy code.
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24674>
Instead, we replace it directly with nir_def. We could replace it with
nir_dest but the next commit gets rid of that so this avoids unnecessary
churn. Most of this commit was generated by sed:
sed -i -e 's/dest.dest.ssa/def/g' src/**/*.h src/**/*.c src/**/*.cpp
There were a few manual fixups required in the nir_legacy.c and
nir_from_ssa.c as nir_legacy_reg and nir_parallel_copy_entry both have a
similar pattern.
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24674>
We could add a nir_def_num_components() helper but we use
ssa.num_components about 3x as often as nir_dest_num_components() today
so that's a major Coccinelle refactor anyway and this doesn't make it
much worse. Most of this commit was generated byt the following
semantic patch:
@@
expression D;
@@
<...
-nir_dest_num_components(D)
+D.ssa.num_components
...
Some manual fixup was needed, especially in cpp files where Coccinelle
tends to give up the moment it sees any interesting C++.
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24674>
We could add a nir_def_bit_size() helper but we use ->bit_size about 3x
as often as nir_dest_bit_size() today so that's a major Coccinelle
refactor anyway and this doesn't make it much worse. Most of this
commit was generated byt the following semantic patch:
@@
expression D;
@@
<...
-nir_dest_bit_size(D)
+D.ssa.bit_size
...
Some manual fixup was needed, especially in cpp files where Coccinelle
tends to give up the moment it sees any interesting C++.
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24674>
