This commit adds a new "discarded" state for registers.
Discarding a register is like flushing it, but without
actually writing its value back to memory. We can discard
a register only when it is guaranteed that no instruction
will read from the register before it is next written to.
Discarding reduces the register pressure a little, and can
also let us skip a few flushes on interpreter fallbacks.
The output of instructions like fabsx and ps_sel is store-safe
if and only if the relevant inputs are. The old code was always
marking the output as store-safe if the output was a single,
and never otherwise.
Also, the old code was treating the output of psq_l/psq_lu as
store-safe, which seems incorrect (if dequantization is disabled).
If we know at compile time that the PPC carry flag definitely
has a certain value, we can bake that value into the emitted code
and skip having to read from PPCState.
When a save state is loaded, the IOS device serving bluetooth
is cast as BluetoothEmuDevice. If, however, a real Wiimote
with BT passthrough is used, this caused the game to crash.
Now the proper device class is used.
At a first glance it may look like a part of the code I added to
srawx in efeda3b has a bug when a == s. The code actually happens
to work correctly, but in the interest of making the code easier
to reason about, I'd like to change the way it's implemented. This
change should improve the pipelining a little in the a == s case too.
21c152f added a small hack to DVDInterface to keep WBFS and CISO
files working with Nintendo's "Error #001" anti-piracy check.
Unfortunately I don't think it's possible to support WBFS and
CISO without any kind of hack or heuristic, but what we can do
is replace the 21c152f hack (which applies regardless of file
format) with a hack that only is active when using WBFS or CISO.
This change is similar to 2a5a399, but the disc size is
calculated in a different way.
...and let's optimize a divisor of 2 ever so slightly for good measure.
I wouldn't have bothered, but most GameCube games seem to hit this on
launch.
- Division by 2
Before:
41 BE 02 00 00 00 mov r14d,2
41 8B C2 mov eax,r10d
45 85 F6 test r14d,r14d
74 0D je overflow
3D 00 00 00 80 cmp eax,80000000h
75 0E jne normal_path
41 83 FE FF cmp r14d,0FFFFFFFFh
75 08 jne normal_path
overflow:
C1 F8 1F sar eax,1Fh
44 8B F0 mov r14d,eax
EB 07 jmp done
normal_path:
99 cdq
41 F7 FE idiv eax,r14d
44 8B F0 mov r14d,eax
done:
After:
45 8B F2 mov r14d,r10d
41 C1 EE 1F shr r14d,1Fh
45 03 F2 add r14d,r10d
41 D1 FE sar r14d,1
Add a function to calculate the magic constants required to optimize
signed 32-bit division.
Since this optimization is not exclusive to any particular architecture,
JitCommon seemed like a good place to put this.
Zero divided by any number is still zero. For whatever reason, this case
shows up frequently too.
Before:
B8 00 00 00 00 mov eax,0
85 F6 test esi,esi
74 0C je overflow
3D 00 00 00 80 cmp eax,80000000h
75 0C jne normal_path
83 FE FF cmp esi,0FFFFFFFFh
75 07 jne normal_path
overflow:
C1 F8 1F sar eax,1Fh
8B F8 mov edi,eax
EB 05 jmp done
normal_path:
99 cdq
F7 FE idiv eax,esi
8B F8 mov edi,eax
done:
After:
Nothing!
When the dividend is known at compile time, we can eliminate some of the
branching and precompute the result for the overflow case.
Before:
B8 54 D3 E6 02 mov eax,2E6D354h
85 FF test edi,edi
74 0C je overflow
3D 00 00 00 80 cmp eax,80000000h
75 0C jne normal_path
83 FF FF cmp edi,0FFFFFFFFh
75 07 jne normal_path
overflow:
C1 F8 1F sar eax,1Fh
8B F8 mov edi,eax
EB 05 jmp done
normal_path:
99 cdq
F7 FF idiv eax,edi
8B F8 mov edi,eax
done:
After:
85 FF test edi,edi
75 04 jne normal_path
33 FF xor edi,edi
EB 0A jmp done
normal_path:
B8 54 D3 E6 02 mov eax,2E6D354h
99 cdq
F7 FF idiv eax,edi
8B F8 mov edi,eax
done:
Fairly common with constant dividend of zero. Non-zero values occur
frequently in Ocarina of Time Master Quest.
Whether the custom RTC setting is enabled shouldn't in itself
affect determinism (as long as the actual RTC value is properly
synced). Alters the logic added in 4b2906c.
I'm not entirely certain that this is correct, but the current
code doesn't really make sense to me... If we need to force the
RTC bias to 0 when custom RTC is enabled, why don't we need to
do it when custom RTC is disabled? The code for getting the
host system's current time doesn't contain any special handling
for the guest's RTC bias as far as I can tell.
Additionally, VCacheEnhance has been added to UVAT_group1. According to YAGCD, this field is always 1.
TVtxDesc also now has separate low and high fields whose hex values correspond with the proper registers, instead of having one 33-bit value. This change was made in a way that should be backwards-compatible.
