JitArm64: Optimize frsqrte routine #12231
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Instead of combining X2 (the exponent) and X3 (the mantissa) using an ORR instruction, we can read X1, which already contains both. This requires us to reconstruct X1 in the denormal path, but that's an acceptable price.
With this, the normal path is no longer reading the value in X3, which opens up for the next commit.
Now that the normal path is no longer reading X2 and X3, it doesn't matter what the denormal path writes to them.
This required a change in the denormal path where, instead of subtracting 11 before shifting left, we shift left immediately and then shift right by 11. This shouldn't affect performance.
If we hit the denormal path, the sign and exponent are guaranteed to be 0, which means X1 and X3 have the same value.
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lioncash
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Nov 28, 2023
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