Optimise primitive_restart::upload_untouched()

[linkmauve]

This optimisation targets SSE4.1 and is only applied when skip_restart is false.

I’ve only tested the u16 codepath, as it is the one used in NieR.

In some very unscientific profiling, this function used to take 2.76% of the total time at some spot of the port town, it now takes about 0.40% on SSE4.1, and 0.30% on AVX2.

[Illynir]

I tested, +3/4 FPS on Nier Replicant/NieR on my test spot (61 FPS -> 64,5 FPS).
There will probably be other games affected but we have to find them.

Nice. :)

[linkmauve]

It seems your Linux CI isn’t configured to allow AVX2, so for now I added #if __AVX2__ guards around this code, the SSE4.1 speedup is already nice on its own.

[Illynir]

I tested a few other games besides Nier to see the impact elsewhere.

• 1 FPS on Uncharted
• 2 FPS on Yakuza 3
• 1 FPS on Wipeout HD Fury
• 2 FPS on Dragon quest Builders

We could say that it is within the margin of calculation error but it is very consistent so the gain is real. I found no regression for the moment.

[kd-11]

I feel like we're not communicating effectively. We don't need the gcc attributes check in this case. Only local users build with march=native, appimages build with march=sse2 always. In fact, appimages don't even build with gcc at all, we use clang for the official builds. With that being said, you find a curious difference between GCC and Clang; clang does not allow the method definitions to even exist if the march level is below it; i.e if march is SSE2 all SSE3 intrinsics will be undefined methods and throw errors, hence the inline asm workarounds.

[linkmauve]

It actually was a typo (I added a semicolon after the __attribute__ in the previous revision…) that prevented both clang and gcc from using the AVX2 version.

With this attribute in place now, I believe we build both versions on all three OSes, and select the correct one at runtime.

[linkmauve]

There, I believe I fixed all of your comments. I also split the commits so that they are easier to understand separately.

[kd-11]

Well, the target attribute doesn't work the way you want it to, but it got clang to compile AVX and SSE4.1 code without much problem which is a win. Multiversioning usually works if there is a fallback overload with the same function name marked with a "default" target. Its not important for rpcs3 anyway and the proposed solution does generate the assembly output I wanted so it should be good. I'll have to check the u32 paths though since they're untested.

[linkmauve]

Do you have a stash of tests btw, so that I could verify I’m not regressing things in the future?

[kd-11]

Yes, I have a stash of tests, but not for this particular situation. I do provide them and reference data if you happen to touch something that I have hardware tests for. I should probably put them somewhere easily accessible.

[linkmauve]

I haven’t been able to get anything but a black screen out of this rrc file, so not yet. Do you have any idea what could cause it? Also, is there a simpler way than drag and drop to open this file? I couldn’t find any menu or command line way. ^^'

[kd-11]

You need to enable the debug tab in your GuiConfig.ini file inside the GuiConfigs folder in your config folder. I think on linux its ~/.config/rpcs3/GuiConfigs. Set ShowDebugTab to true and a new Utilities menu will appear where you can run rrc files from. Note that RRC files will execute using your global configuration, so make sure to set up correctly. Disable asynchronous shaders when loading RRC files to avoid possible corruption.

[linkmauve]

Thanks, MGS4 is now fixed, the issue was that the indices remaining after the SIMD version ran were written in the wrong order, from last to first…

This trace also let me find this bug using anv: #6916.

[kd-11]

This will break bisect since we now have a sequence of commits that are all broken fixed by a commit at the end. I'll just squash them all during merge to avoid this, but for future reference it would have been nice to not have to.

[linkmauve]

I can reorder them, no worries. That’s much better than squashing.

[illusion0001]

Typo in commit description
rsx: Write the ibo tail in the correct order
Fixes MSG4’s graveyard scene.

[linkmauve]

There, should be fine for merging now. :)

I did test all four commits for no regression on both NieR and this MGS4 rrc.

[kd-11]

I'd prefer to leave this up for a day or so to allow for more user testing. Code looks ok at a glance.

[linkmauve]

Optimisation added, even though it only gets called once per copy so it’s not very hot. I also couldn’t find any information in the Intel manuals on the latency and throughput of vphminposuw, but I assume the sheer amount of instructions removed is worth it.

[isJuhn]

I use Agner's instruction tables as a reference for that kind of stuff. It includes cycles, latency and more for lots of x86 CPUs.

[linkmauve]

Why did you squash anyway in the end?

[Nekotekina]

I'm sorry, didn't realize the communication regarding it

[linkmauve]

No worries, I was just surprised. :)