[stdlib] Simplify Int.__floordiv__ and friends
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soraros
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Sep 18, 2024
stdlib/src/builtin/int.mojo
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| var mod = self - div * rhs | ||
| var divMod = select(((rhs < 0) ^ (self < 0)) & mod, div - 1, div) | ||
| div = select(self > 0 & rhs > 0, div, divMod) |
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The first branch was never taken anyways, since
self > 0 & rhs > 0
=
self > (0 & rhs) > 0
=
self > 0 > 0
=
False
soraros
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Int.__floordiv__ and friendsInt.__floordiv__ and friends
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!sync |
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JoeLoser
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Sep 19, 2024
| if ((rhs < 0) ^ (self < 0)) & mod: | ||
| return div - 1, mod + rhs | ||
| return div, mod | ||
| return self // rhs, self % rhs |
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Question By recomputing things, won't this regress performance a bit?
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Both // and % are marked as always_inline and they share most of the code; I just assume that the compiler can see through the defs and do CSE well. I can inline and do a manual dedup if you so prefer.
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As a ref point, UInt also does this.
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I checked and they generates identical assembly.
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Signed-off-by: Yiwu Chen <[email protected]>
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