In a code block where a guest register is accessed at least twice and the
last access is a write and the register is not discardable immediately
after the second-to-last instruction (perhaps there is an instruction
in between that can cause an exception), currently Dolphin's JITs will
flush the register after the second-to-last instruction.
It would be better if we replaced the flush after the second-to-last
instruction with a flush that only happens if the exception path is
taken. This change accomplishes that by marking guest registers as
"in use" not just when they are used as inputs but also when they are
used as outputs, preventing the loop in DoJit from flushing the
register until after the last access.
This makes codegen faster (by perhaps 10-20% in the case of Jit64,
I didn't measure too closely), which helps speed up NBA Live 2005
a little. But the game still has serious performance issues.
The DSP JIT only applies on x64, so if it doesn't work on esoteric compilers then that's not a problem. (And if it fails to compile, then it'll still produce an error on that platform, just no warnings on other platforms)
The size variable started to be unused when I created std::array variants of ReadArray, but we should follow it in case any files have fewer registers stored than they should (otherwise the remaining registers would end up with garbage data from later in the fifolog). Though, there probably aren't many fifologs where this is relevant.
Large amounts of logging can have an impact on performance, so moving the ones that have been determined to not matter to the warn level gives a way to hide those messages without hiding actual errors (and also gives a fast visual way of distinguishing between ignored and non-ignored ones due to the different colors).
Fixes https://bugs.dolphin-emu.org/issues/12827.
A description of what was going wrong:
JitArm64::Init first calls CodeBlock::AllocCodeSpace, after which
CodeBlock and Arm64Emitter consider us to have 96 MB of code space
available. JitArm64::Init then calls AddChildCodeSpace, which is
supposed to take 64 MiB of that space and give it to m_far_code.
CodeBlock's view of how much space there is gets updated from 96 MiB
to 32 MiB, but due to the missing call, Arm64Emitter keeps thinking
that it has 96 MiB of space available.
The last thing JitArm64::Init does is to call ResetFreeMemoryRanges.
This function asks Arm64Emitter how much code space is available and
stores a range of that size in m_free_ranges_near, meaning that
m_free_ranges_near ends up being backed by both nearcode and farcode!
This is a ticking time bomb; as soon as we grab memory from
m_free_ranges_near which is backed by farcode, we're in trouble.
The crash I ran into in my testing was caused by fastmem code being
allocated in farcode (our backpatch handler only handles accesses made
from nearcode), but you may as well get errors caused by code intended
for nearcode overwriting code intended for farcode or vice versa.
So why did NBA Live 2005 crash when most games had no problems,
and why was the bug bisected to the commit that increased the size
of far code from 16 MiB to 64 MiB? Well, as long as we're only
using the first 32 MiB of the big 96 MiB range, everything works.
What happens with NBA Live 2005 (I have not investigated exactly
through what mechanism this happens) is that at some point the range
in m_free_ranges_near gets split into two ranges, one which is
backed by nearcode and one which is backed by farcode. Dolphin
prefers to select the biggest range available (we don't want to
pick a tiny 1 KiB range that may not be able to fit the whole block
we're about to emit, after all), and after increasing the size of
farcode to 64 MiB, farcode is bigger than nearcode.
It doesn't make sense for alpha to add the bias ONLY when dividing by 2, while color doesn't apply the bias for divide by 2 only; hardware testing indicates that alpha should have the bias.
This fixes the menus in Mario Kart Wii (https://bugs.dolphin-emu.org/issues/11909) but reintroduces the white rectangle in Fortune Street.
This reverts commit 5aaa5141ed (and several other matching changes elsewhere).
JosJuice