Fixes https://bugs.dolphin-emu.org/issues/12327.
When we started using fmt in CheckExternalExceptions, JitArm64
mysteriously stopped working even though the code path where
fmt was used never was reached. This is because the compiler
added a function prologue and epilogue to set up the stack,
since the code path that used fmt required the use of the stack.
However, the breakage didn't actually have anything to do
with the usage of the stack in itself, but rather with the
compiler's insertion of a stack canary. In the function
epilogue, a cmp instruction was inserted to check that the
stack canary had not been overwritten during the execution
of the function. This cmp instruction overwriting the status
flags ended up having a disastrous side effect once execution
returned to code emitted by JitArm64::WriteExceptionExit.
JitArm64's dispatcher contains a branch to the "do_timing"
code which is intended to be taken if the PPC downcount is
negative. However, the dispatcher doesn't update the status
flags on its own before this conditional branch, but rather
expects the calling code to have set them as a side effect
of DoDownCount. The root cause of our bug was that
JitArm64::WriteExceptionExit was calling DoDownCount before
Check(External)Exceptions instead of after.
1. Comparing string_views does not behave the same as strncmp
in the case where SConfig's game ID is longer than 6 chars.
2. DTMHeader::GetGameID wasn't excluding null bytes for game IDs
shorter than 6 chars.
3. == was accidentally used instead of !=.
This issue is both severe and surprisingly difficult to find
the root cause of, so I think it would make sense to add a simple
hotfix for now. https://bugs.dolphin-emu.org/issues/12327
Fallback Region
A user-selected fallback to use instead of the default PAL
This is used for unknown region or region free titles to give them
the ability to force region to use. This replaces the current fallback region
of PAL. This can be useful if a user is trying to play a region free
tilte that is originally NTSC and expects to be run at NTSC speeds. This
may be done when a user attempts to dump a WAD of their own without
understanding the settings they have chosen, or could be an intentional
decision by a developer of a ROM hack that can be injected into a
Virtual Console WAD.
Remove using System Menu region being checked in GetFallbackRegion
Use DiscIO::Region instead of std::String for fallback
Add explanation text for Fallback Region
Unfortunately, adding a DEBUG_ASSERT_MSG_FMT isn't actually possible
right now because of compiler bugs:
https://github.com/dolphin-emu/dolphin/pull/9284
We could require a newer version of GCC (10) but that would require
updating GCC on the build machines.
For what it's worth, older versions of GCC (8, 9) are broken in
many ways: adding constexpr to some Matrix functions causes GCC 8
to generate bugged code that causes the Wii IR pointer to disappear,
which means that the generated builds are already unusable
(see https://dolp.in/i12324).
Additionally, we've already had to add workarounds for those versions
in the format macros to fix compilation bugs. This time, it looks like
workarounds won't cut it; even applying the workaround
described in https://github.com/fmtlib/fmt/pull/1580 does not help.
/Externals/liblzma/config.h #defines HAVE_PTHREAD_CONDATTR_SETCLOCK
which results in /Externals/liblzma/tuklib/mythread.h calling the
function pthread_condattr_setclock. This function doesn't exist in
macOS 10.12+, which are the only macOS versions Dolphin supports, but
inserting an include guard makes macOS use an alternate function.
On Windows, when the Rename function fails to replace an existing file
it will now retry the operation multiple times with increasingly long
delays between attempts. This fixes transient rename failures.
I've been getting sporadic yet annoyingly frequent errors saying:
'IOS_FS: Failed to rename temporary FST file'
These typically appear on startup but I've also gotten them randomly.
Investigation shows this happens when the Windows ReplaceFile function
returns the error ERROR_UNABLE_TO_REMOVE_REPLACED. That happens in the
context of using ReplaceFile to perform an atomic file overwrite, which
is required when saving updates to a file to avoid corruption. The
error mainly happens with the /Wii/fst.bin file but I've seen it
happen with multiple other files as well.
I haven't been able to definitively pin down why the error occurs,
though online discussions suggest antivirus scanning may be a major
culprit. That said, I've excluded the Dolphin folder from Windows
Defender scans to no avail and don't have any other antivirus running,
so this is likely to be a problem others are experiencing as well.
The number and duration of retry delays is arbitrary but I feel like a
combined second or so in the worst case is an acceptable tradeoff for
the reduction (actually elimination in my experience) of those errors.
This is even more true when you consider the time it takes to read and
dismiss the error dialogs.
Ryan Meredith