A bit of refactoring necessary before we can move the remaining Linux
specific code to the frontend.
Most of this taken from #3535 but attempting to be NFC as much as
possible.
A feature of FEX's JIT is that when an unaligned atomic load/store
operation occurs, the instructions will be backpatched in to a barrier
plus a non-atomic memory instruction. This is the half-barrier technique
that still ensures correct visibility of loadstores in an unaligned
context.
The problem with this approach is that the dmb instructions are HEAVY,
because they effectively stop the world until all memory operations in
flight are visible. But it is a necessary evil since unaligned atomics
aren't a thing on ARM processors. FEAT_LSE only gives you unaligned
atomics inside of a 16-byte granularity, which doesn't match x86
behaviour of cacheline size (effectively always 64B).
This adds a new TSO option to disable the half-barrier on unaligned
atomic and instead only convert it to a regular loadstore instruction,
ommiting the half-barrier. This gives more insight in to how well a
CPU's LRCPC implementation is by not stalling on DMB instructions when
possible.
Originally implemented as a test to see if this makes Sonic Adventure 2
run full speed with TSO enabled (but all available TSO options disabled)
on NVIDIA Orin. Unfortunately this basically makes the code no longer
stall on dmb instructions and instead just showing how bad the LRCPC
implementation is, since the stalls show up on `ldapur` instructions
instead.
Tested Sonic Adventure 2 on X13s and it ran at 60FPS there without the
hack anyway.
This may be useful for tracking TSO faulting when it manages to fetch
stale data. While most TSO crashes are due to nullptr dereferences, this
can still check for the corruption case.
FEXCore doesn't need track the TLS state of the SignalDelegator, this is
a frontend concept.
Removes the tracking from the backend and keeps it in the frontend.
Which requires moving LinuxEmulation to its own independent folder as
well. Since both IRLoader and FEXLoader rely on it.
No functional change, just moves the the code around.
Ryan Houdek