Not doing this can cause desyncs when TASing. (I don't know
how common such desyncs would be, though. For games that
don't change rounding modes, they shouldn't be a problem.)
When I added the software FMA path in 2c38d64 and made us use
it when determinism is enabled, I was assuming that either the
performance impact of software FMA wouldn't be too large or CPUs
that were too old to have FMA instructions were too slow to run
Dolphin well anyway. This was wrong. To give an example, the
netplay performance went from 60 FPS to 30 FPS in one case.
This change makes netplay clients negotiate whether FMA should
be used. If all clients use an x64 CPU that supports FMA, or
AArch64, then FMA is enabled, and otherwise FMA is disabled.
In other words, we sacrifice accuracy if needed to avoid massive
slowdown, but not otherwise. When not using netplay, whether to
enable FMA is simply based on whether the host CPU supports it.
The only remaining case where the software FMA path gets used
under normal circumstances is when an input recording is created
on a CPU with FMA support and then played back on a CPU without.
This is not an especially common scenario (though it can happen),
and TASers are generally less picky about performance and more
picky about accuracy than other users anyway.
With this change, FMA desyncs are avoided between AArch64 and
modern x64 CPUs (unlike before 2c38d64), but we do get FMA
desyncs between AArch64 and old x64 CPUs (like before 2c38d64).
This desync can be avoided by adding a non-FMA path to JitArm64 as
an option, which I will wait with for another pull request so that
we can get the performance regression fixed as quickly as possible.
https://bugs.dolphin-emu.org/issues/12542
The SDK seems to write "default" bounding box values before every draw
(1023 0 1023 0 are the only values encountered so far, which happen to
be the extents allowed by the BP registers) to reset the registers for
comparison in the pixel engine, and presumably to detect whether GX has
updated the registers with real values. Handling these writes and
returning them on read when bounding box emulation is disabled or
unsupported, even without computing real values from rendering, seems
to prevent games from corrupting memory or crashing.
This obviously does not fix any effects that rely on bounding box
emulation, but having the game not clobber its own code/data or just
outright crash is a definite improvement.
When determinism is enabled, we either want all CPUs to use FMA or
we want no CPUs to use FMA. Until now, Jit64 has been been doing
the latter. However, this is inaccurate behavior, all CPUs since
Haswell support FMA, and getting JitArm64 to match the exact
inaccurate rounding used by Jit64 would be a bit annoying. This
commit switches us over to using FMA on all CPUs when determinism
is enabled, with older CPUs calling the std::fma function.
Added RAII wrapper around the the JITPageWriteEnableExecuteDisable() and
JITPageWriteDisableExecuteEnable() to make it so that it is harder to forget to
pair the calls in all code branches as suggested by leoetlino.
Removed the unavailable CPU core dialog box that asked users to change their
selected CPU core to one that is available. Instead, Dolphin now just overrides
the core to the default, and logs that it performed the override.
Analytics:
- Incorporated fix to allow the full set of analytics that was recommended by
spotlightishere
BuildMacOSUniversalBinary:
- The x86_64 slice for a universal binary is now built for 10.12
- The universal binary build script now can be configured though command line
options instead of modifying the script itself.
- os.system calls were replaced with equivalent subprocess calls
- Formatting was reworked to be more PEP 8 compliant
- The script was refactored to make it more modular
- The com.apple.security.cs.disable-library-validation entitlement was removed
Memory Management:
- Changed the JITPageWrite*Execute*() functions to incorporate support for
nesting
Other:
- Fixed several small lint errors
- Fixed doc and formatting mistakes
- Several small refactors to make things clearer
