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JitArm64: divwx - Optimize division by 2 

...and let's optimize a divisor of 2 ever so slightly for
good measure. Most GameCube games seem to hit this on launch.
This commit is contained in:
JosJuice 2021-08-21 18:59:55 +02:00
parent 9889e7eb33
commit 91b112b984
1 changed files with 12 additions and 0 deletions
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12
Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
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@ -1394,6 +1394,18 @@ void JitArm64::divwx(UGeckoInstruction inst)
gpr.Unlock(WA);
}
else if (divisor == 2 || divisor == -2)
{
ARM64Reg RA = gpr.R(a);
ARM64Reg RD = gpr.R(d);
ADD(RD, RA, RA, ArithOption(RA, ShiftType::LSR, 31));
if (divisor < 0)
NEG(RD, RD, ArithOption(RD, ShiftType::ASR, 1));
else
ASR(RD, RD, 1);
}
else if (MathUtil::IsPow2(divisor) || MathUtil::IsPow2(-static_cast<s64>(divisor)))
{
const u32 abs_val = static_cast<u32>(std::abs(static_cast<s64>(divisor)));