JitArm64: Optimize divwx #10057
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JitArm64: Optimize divwx #10057
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When the dividend is known at compile time, we can eliminate some of the branching and precompute the result for the overflow case.
Zero divided by any number is still zero. For whatever reason, this case shows up frequently too.
Optimize division by a constant into multiplication. This method is also used by GCC and LLVM. We also add optimized paths for divisors 0, 1, and -1, because they don't work using this method. They don't occur very often, but are necessary for correctness.
Power-of-two divisors can be done more elegantly, so handle them separately.
...and let's optimize a divisor of 2 ever so slightly for good measure. Most GameCube games seem to hit this on launch.
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leoetlino
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Reviewed 3 of 3 files at r1, 1 of 1 files at r2, 1 of 1 files at r3, 2 of 2 files at r4, 1 of 1 files at r5, 1 of 1 files at r6, all commit messages.
Reviewable status:complete! all files reviewed, all discussions resolved (waiting on @JosJuice)
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JitArm64 port of PR #9566.