JIT code related to Branch Watch was emitted if the debugging UI was active: the emitted code would dynamically check whether Branch Watch is active.
However, this causes two problems:
1. It decreases performance by just having the debugging UI enabled
2. It clutters the host assembly in the JIT tab, making it harder to read (unaware readers will wonder what these instructions are for)
With this PR, code related to Branch Watch is emitted only if Branch Watch itself is active, fixing the issues above.
The JIT cache will now be wiped whenever the feature is toggled, causing a slight stutter. However, this isn't the kind of feature that is toggled over and over, so IMO it is an acceptable trade-off.
The functions SaveToSYSCONF and LoadFromSYSCONF contain checks for
whether emulation is running. The intent of this is that when we're
emulating a Wii, the emulated system may write to SYSCONF whenever it
likes and does not expect anything else to write to SYSCONF, so the
host code shouldn't access SYSCONF while emulation is ongoing. However,
Core::IsRunning is an imperfect proxy for whether we've handed over
control of SYSCONF to the emulated system yet, as the actual handover
happens at a slightly different point in time than when the emulation
state is changed. This usually isn't a problem, but in theory it could
be a determinism problem if a setting is changed right as emulation is
starting, or it could cause the emulated software to briefly misbehave
if a setting is changed right as emulation is stopping.
Things got worse in 72cf2bdb87 when I
replaced the Core::IsRunning calls with !Core::IsUninitialized. With
IsRunning, there was be a period of time where SYSCONF should have been
protected but wasn't. With !IsUninitialized, there was a period of time
where SYSCONF shouldn't have been protected but was, and crucially, this
period of time included the moments where we do setup and teardown of
the emulated NAND, which broke transferring SYSCONF settings between the
host and the guest. 72cf2bdb87 was
reverted because of this.
This commit adds a flag that we explicitly flip when control is handed
over to or from the emulated system. This protects the SYSCONF file
for exactly as long as is needed.
Previously, when an input device was connected or disconnected, we would
recreate all devices. This commit makes it so we only touch the relevant
device instead. This matters because recreating a device causes us to
drop all held buttons for that device. Due to Android only delivering
inputs as events, we're unable to poll for currently held buttons when
recreating a device.
This recently became a problem for users of Ayn devices due to a
firmware update. Every now and then, something about the display
viewports changes, triggering an update to an input device that I assume
is a touch input device. This input device isn't something users
normally map in Dolphin's controller settings, but it changing was
causing Dolphin to drop all held buttons for the device's built-in
gamepad as well as any other connected gamepads.
In the unit test I'm adding in the next commit, I want to call
MemoryManager::Init, but initializing all the hardware that
MemoryManager::InitMMIO calls into would be cumbersome.
Calling MemoryManager::InitMMIO from MemoryManager::Init was a bit
strange anyway. Because MemoryManager::Init is called about halfway
through HW::Init, some of the hardware that MemoryManager::InitMMIO
calls into isn't initialized yet.
Most systems that Dolphin runs on have a page size of 4 KiB, which
conveniently matches the page size of the GameCube and Wii. But there
are also systems that use larger page sizes, notably Apple CPUs with
16 KiB page sizes. To let us create host mappings on such systems, this
commit implements combining guest mappings into host page sized mappings
wherever possible.
For this to work for a given mapping, not only do four (in the case of
16 KiB) guest mappings have to exist adjacent to each other, but the
corresponding translated addresses also have to be adjacent, and the
lowest bits of the addresses have to match. When I tested a few games,
the following percentages of guest mappings met these criteria:
Spider-Man 2: 0%-12%
Rogue Squadron 2: 39%-42%
Rogue Squadron 3: 28%-41%
So while 16 KiB systems don't get as much of a performance improvement
as 4 KiB systems, they do still get some improvement.
Removing and readding every page table mapping every time something
changes in the page table is very slow. Instead, let's generate a diff
and ask Memmap to update only the diff.
Page table mappings are only used when DR is set, so if page tables are
updated when DR isn't set, we can wait with updating page table mappings
until DR gets set. This lets us batch page table updates in the Disney
Trio of Destruction, improving performance when the games are loading
data. It doesn't help much for GameCube games, because those run tlbie
with DR set.
The PowerPCState struct has had its members slightly reordered. I had to
put pagetable_update_pending less than 4 KiB from the start so AArch64's
LDRB (immediate) can access it, and I also took the opportunity to move
some other members around to cut down on padding.
Previously we've only been setting up fastmem mappings for block address
translation, but now we also do it for page address translation. This
increases performance when games access memory using page tables, but
decreases performance when games set up page tables.
The tlbie instruction is used as an indication that the mappings need to
be updated.
There are some accuracy downsides:
* The TLB is now effectively infinitely large, which matters if games
don't use tlbie when modifying page tables.
* The R and C bits for page table entries get set pessimistically rather
than when the page is actually accessed.
No games are known to be broken by these inaccuracies, but unfortunately
the second inaccuracy causes a large performance regression in Rogue
Squadron 3. You still get the old, more accurate behavior if Enable
Write-Back Cache is on.
