See the comment added by this commit. We were previously guarding against
overshooting in address calculations, but not against undershooting.
Perhaps someone assumed that the displacement of an x86 loadstore was
treated as unsigned?
Note: While the comment says we can undershoot by up to 2 GiB, in
practice Jit64 as it currently behaves won't actually undershoot by more
than 0x8000 if my analysis is correct. But address space is cheap, so
let's guard the full 2 GiB.
Back when this was just the FPS setting, having it in the top level
of the graphics settings was reasonable. But now it's seven settings.
Let's add a new submenu for them.
Plus two miscellaneous debugger features that I found along the way when
reading Jit64's code for comparison: bJITNoBlockLinking and tracing.
Fixes https://bugs.dolphin-emu.org/issues/13127.
Small optimization. By not calling WriteExit, the block linking system
never finds out about the exit we're doing, saving us from having to
disable block linking.
We should expose Enable Controller Input and the turbo settings for
GBA just like we do for GameCube controllers and Wii Remotes.
I just forgot about it when implementing the GBA TAS input window.
Previously, if a user on Windows launched Dolphin from the command line
and specified a path to an M3U file and included backslashes in this path,
Dolphin would fail to resolve relative paths in the M3U file.
The calculation of each address in lmw/stmw currently has a dependency
on the calculation of the previous address. By removing this dependency,
the host CPU should be able to pipeline the loads/stores better. The cost
we pay for this is up to one extra register and one extra MOV instruction
per guest instruction, but often nothing.
Making EmitBackpatchRoutine support using any register as the address
register would let us get rid of the MOV, but I consider that to be too
big of a task to do in one go at the same time as this.
Now that we've flipped the C++20 switch, let's start making use of
the nice new <bit> header.
I'm planning on handling this move away from BitUtils.h incrementally
in a series of PRs. There may be a few functions remaining in
BitUtils.h by the end that C++20 doesn't have any equivalents for.
This reverts commit 351d095fff.
In hindsight, my attempted optimization messes with the return
predictor, unlike real tail calls. So I think it does more bad than
good.
The "vector shift by immediate" category encodes the shift amount for
right shifts as `size - amount`, whereas left shifts use `amount`.
We're not actually using SHRN/SHRN2 anywhere, which is why this has gone
undetected.
For quite some time now, we've had a setting on x86-64 that makes Dolphin
handle NaNs in a more accurate but slower way. There's only one game that
cares about this, Dragon Ball: Revenge of King Piccolo, and what that game
cares about more specifically is that the default NaN (or "generated NaN"
as I believe it's called in PowerPC documentation) is the same as on
PowerPC. On ARM, the default NaN is the same as on PowerPC, so for the
longest time we didn't need to do anything special to get Dragon Ball:
Revenge of King Piccolo working. However, in 93e636a I changed how we
handle FMA instructions in a way that resulted in the sign of NaNs
becoming inverted for nmadd/nmsub instructions, breaking the game.
To fix this, let's implement the AccurateNaNs setting, like on x86-64.
Operations that have two operands and can't generate a default NaN,
i.e. addition and subtraction, already have the desired NaN handling
on x86. We just need to make sure to not reverse the operands.
This fixes ps_sum0/ps_sum1 outputting NaNs in cases where they shouldn't.
(HandleNaNs assumes that a NaN in a ps0 input always results in a NaN in
the ps0 output, and correspondingly for ps1.)
1. In some cases, ps_merge01 can be implemented using one instruction.
2. When we need two instructions for ps_merge01, it's best to start with
a MOV to avoid false dependencies on the destination register.
3. ps_merge10 can be implemented using a single EXT instruction.
This new function is like MOVP2R, except it masks out the lower 12 bits,
returning them instead of writing them to the register. These lower
12 bits can then be used as an offset for LDR/STR. This lets us turn
ADRP+ADD+LDR sequences with a zero offset into ADRP+LDR sequences with
a non-zero offset, saving one instruction.
When emulated GBAs were added to Dolphin, it was possible to control them
using the GC TAS input window. (Z was mapped to Select.) Unaware of this,
I broke the functionality in b296248.
To make it possible to control emulated GBAs using TAS input again,
I'm adding a proper TAS input window for GBAs, with a real Select button
and no analog controls.
I recently talked to a homebrew developer who was trying to add exception
handlers at link time but found out that Dolphin was overwriting their
exception handlers. I figure that's not the usual way to do exception
handlers, but... making us load the executable after setting up memory
rather than before is easy, and matches what we do when booting discs,
so I suppose there's no reason not to do it. It also matches the intent
of why Dolphin is writing default exception handlers – we're writing
them because some homebrew relies on exception handlers being left
around from whatever program was running before it (see 3dd777be70).
Because of the previous commit, `regs_in_use` must not include `dest_reg`
when calling MMIOLoadToReg. There are also some other registers we can
skip including in regs_in_use just for efficiency's sake.
The `addr_reg_set = false` statements that I've added in this commit are
technically redundant – if `mmio_address` is non-zero then `addr_reg_set`
is already false – but it's just a coincidence that that's the case.
This adds PR 10890's new setting to the Android GUI. I'm curious to see
if any Android users might get a performance improvement from it.
Due to how our settings work on Android, I haven't implemented disabling
the checkbox when the graphics backend doesn't support both GS and VS
for point/line expansion, but I don't think that's critical to have.
The previous implementation of Force25BitPrecision was essentially a
translation of the x86-64 implementation. It worked, but we can make a
more efficient implementation by using an AArch64 instruction I don't
believe x86-64 has an equivalent of: URSHR. The latency is the same as
before, but the instruction count and register count are both reduced.
The new `dispatcher_no_timing_check` is the same as `dispatcher_no_check`
except it includes the "stepping check" in debug mode. This lets us avoid
the `m_enable_debugging ? dispatcher : dispatcher_no_check` dance.
Maybe "tail call" isn't quite the right term for what this code
is doing, since it's jumping to the dispatcher rather than
returning, but it's the same optimization as for a tail call.
fregsIn will include FD for double-precision instructions, since for
dependency tracking purposes the instruction does read the upper
half of FD. This is not what we want in HandleNaNs.
The consequence of this bug is that if an instruction was supposed to
output a NaN and FD happens to contain a NaN and FD happens to be the
same register as an unused register in the instruction encoding, the
NaN in FD could get used as the output instead of the correct NaN.
This isn't known to affect any games, which isn't especially surprising
considering that there's only one game that needs AccurateNaNs anyway.
Jumping to `dispatcher` requires first subtracting the downcount,
otherwise `dispatcher` may unpredictably jump to CoreTiming::Advance,
which could break determinism compatibility with JitArm64. We should
jump to `dispatcher_no_check` instead.
JosJuice