Update llvm to 21.1.3

[Megamouse]

• Updates LLVM to 21.1.3

TODO:

• update docker
• upload precompiled files

[cipherxof]

I'm getting slightly worse performance in LLVM 20 compared to 19, which already had worse AVX512 performance than LLVM 17 (#16733). Tested on a 8945HS.

LLVM 19:

LLVM 20:

[crashGG]

But there is no
https://github.com/RPCS3/llvm-mirror/releases/download/custom-build-win-20.1.2/llvmlibs_mt.7z
So can't build the win64 version to test.
Can anyone help?

[Megamouse]

There won't be a prebuilt until we decide to merge this.

[Darkhost1999]

Rpcs3_default.props doesn't change from llvm 20.1.7 to 20.1.8.
Are minor performance regressions a stopper for PRs like these?
I thought the goal is to test stability. Performance is allowed to fluctuate a little bit, especially with numbers as high as 120+

[kd-11]

Rpcs3_default.props doesn't change from llvm 20.1.7 to 20.1.8. Are minor performance regressions a stopper for PRs like these? I thought the goal is to test stability. Performance is allowed to fluctuate a little bit, especially with numbers as high as 120+

It's incremental just like optimizations are. We already had another drop coming from 17 to 19 then 19 to 20. Obviously something is wrong and needs to be identified. Otherwise by the time we reach llvm30 we'll have lost a lot of performance without making any significant code changes in our own code.

When no code changes product side have been made, regressions are a lot more concerning than when our own code is being modified because then we know the pros vs cons. We never commit our own code changes if they do nothing but hurt performance - the amount of experimental code that gets thrown out could probably create another (horrible) PS3 emulator.

In this case we have a change that provides zero pros, just cons, making it not worth the effort. If the cause is identified, we can proceed just to be up to date with the latest version of llvm. Something I am curious about is whether the problem goes away if we use the clang64 windows binaries?

[Darkhost1999]

Something I am curious about is whether the problem goes away if we use the clang64 windows binaries?

Wish I could try. But I tend to observe the same "problem" as previously reported with the mgs4 test booting any game on the exact same binary of rpcs3. Let alone a different binary.
I'm not any good at performance tests at all.

[JohnHDev]

Would be good to see if this update fixes this issue: #16676

Happy to try an ARM Mac build if you wanted someone to try it.