Despite being mathematically equivalent, the following code sequences are not
bit-identical under IEEE 754 rules due to differing internal precision:
fadd16 r0l, r2, 0.0 z = f2f16 x
fadd16 r1h, r0l, r0h w = fadd z, y
versus
fadd32 r1h, r2, r0h f2f16(w) = fadd x, f2f32(y)
This is probably fine under GL's relaxed floating point precision rules, but
it's definitely not ok with the more strict OpenCL or Vulkan. It also is a
potential problem with GL invariance rules, if we get different results for the
same shader depending whether we did a monolithic compile or a fast link. The
place for doing inexact transformations is NIR, when we have the information
available to do so correctly. By the time we get to the backend, everything we
do needs to be bit-exact to preserve sanity.
Fixes dEQP-GLES2.functional.shaders.algorithm.rgb_to_hsl_vertex. We believe that
this is a CTS bug, but it's a useful one since it uncovered a serious driver bug
that would bite us in the much less friendly Vulkan (or god forbid OpenCL) CTS
later. It also seems like a magnet for GL app bugs, the fp16 support we do now
is uncovering bad enough bugs as it is.
shader-db results are pretty abysmal, though :|
total instructions in shared programs: 1537964 -> 1571328 (2.17%)
instructions in affected programs: 670231 -> 703595 (4.98%)
total bytes in shared programs: 10533984 -> 10732316 (1.88%)
bytes in affected programs: 4662414 -> 4860746 (4.25%)
total halfregs in shared programs: 483448 -> 474541 (-1.84%)
halfregs in affected programs: 58867 -> 49960 (-15.13%)
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23480>
Also drop my email address in the copyright lines and fix some "Copyright 208
Alyssa Rosenzweig" lines, I'm not *that* old. Together this drops a lot of
boilerplate without losing any meaningful licensing information. SPDX is already
in use for the MIT-licensed code in turnip, venus, and a few other scattered
parts of the tree, so this should be ok from a Mesa licensing standpoint.
This reduces friction to create new files, by parsing the copy/paste boilerplate
and being short enough you can easily type it out if you want. It makes new
files seem less daunting: 20 lines of header for 30 lines of code is
discouraging, but 2 lines of header for 30 lines of code is reasonable for a
simple compiler pass. This has technical effects, as lowering the barrier to
making new files should encourage people to split code into more modular files
with (hopefully positive) effects on project compile time.
This helps with consistency between files. Across the tree we have at least a
half dozen variants of the MIT license text (probably more), plus code that uses
SPDX headers instead. I've already been using SPDX headers in Asahi manually, so
you can tell old vs new code based on the headers.
Finally, it means less for reviewers to scroll through adding files. Minimal
actual cognitive burden for reviewers thanks to banner blindness, but the big
headers still bloat diffs that add/delete files.
I originally proposed this in December (for much more of the tree) but someone
requested I wait until January to discuss. I've been trying to get in touch with
them since then. It is now almost April and, with still no response, I'd like to
press forward with this. So with a joint sign-off from the major authors of the
code in question, let's do this.
Signed-off-by: Asahi Lina <lina@asahilina.net>
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Acked-by: Emma Anholt <emma@anholt.net>
Acked-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Eric Engestrom <eric@igalia.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Rose Hudson <rose@krx.sh>
Acked-by: Lyude Paul [over IRC: "yes I'm fine with that"]
Meh'd-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22062>
Our dead code elimination pass does two things:
1. delete instructions that are entirely unnecessary
2. delete unnecessary destinations of necessary instructions
To deal with pass ordering issues, we sometimes want to do #1 without #2.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21674>
See 0afd691f29 ("panfrost: clang-format the tree") for why I'm doing this.
Asahi already mostly follows Mesa style so this doesn't do much. But this means
we can all stop thinking about formatting and trust the robot poets to do that
for us.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20434>
This means we don't reserve the registers, which improves RA
considerably. Using a special preload psuedo-op instead of a regular
move allows us to constrain semantics and gaurantee coalescing.
shader-db on glmark2 subset:
total instructions in shared programs: 6448 -> 6442 (-0.09%)
instructions in affected programs: 230 -> 224 (-2.61%)
helped: 4
HURT: 0
total bytes in shared programs: 42232 -> 42196 (-0.09%)
bytes in affected programs: 1530 -> 1494 (-2.35%)
helped: 4
HURT: 0
total halfregs in shared programs: 2291 -> 1926 (-15.93%)
halfregs in affected programs: 2185 -> 1820 (-16.70%)
helped: 75
HURT: 0
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18804>
Expecting it to keep around unused definitions around is wishful. Add an
"anchoring" unit_test instruction to consume the results so they don't
have to be precoloured registers.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18687>
Lifted from Bifrost. Add some basic optimizer tests (they pass!) to show the
compiler is ready to be unit tested. Given we can't have hardware CI for Asahi
yet -- and dEQP is still pretty janky -- unit testing should prove quite useful.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16268>
