Use Int256 to reduce BigInts in FD operations. #93
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We do not here explicitly introduce support for FD{BitIntegers.Int256},
though that should work out of the box both before and after this PR.
Rather, this PR _uses_ a (U)Int256 under the hood to prevent allocations
from Int128 widening to BigInt in FD operations.
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I just realized this reimplements RelationalAI-oss#7, from 6 years ago (😳) which @TotalVerb had already reviewed. @TotalVerb you may want to do one more pass over this. |
NHDaly
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Jun 13, 2024
Finally implements the fast-multiplication optimization from #45, but this time for 128-bit FixedDecimals! :) This is a follow-up to #93, which introduces an Int256 type for widemul. However, the fldmod still required 2 BigInt allocations. Now, this PR uses a custom implementation of the LLVM div-by-const optimization for (U)Int256, which briefly widens to Int512 (😅) to perform the fldmod by the constant 10^f coefficient. This brings 128-bit FD multiply to the same performance as 64-bit. :)
NHDaly
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that referenced
this pull request
Jun 13, 2024
Finally implements the fast-multiplication optimization from #45, but this time for 128-bit FixedDecimals! :) This is a follow-up to #93, which introduces an Int256 type for widemul. However, the fldmod still required 2 BigInt allocations. Now, this PR uses a custom implementation of the LLVM div-by-const optimization for (U)Int256, which briefly widens to Int512 (😅) to perform the fldmod by the constant 10^f coefficient. This brings 128-bit FD multiply to the same performance as 64-bit. :)
NHDaly
added a commit
that referenced
this pull request
Jun 13, 2024
Finally implements the fast-multiplication optimization from #45, but this time for 128-bit FixedDecimals! :) This is a follow-up to #93, which introduces an Int256 type for widemul. However, the fldmod still required 2 BigInt allocations. Now, this PR uses a custom implementation of the LLVM div-by-const optimization for (U)Int256, which briefly widens to Int512 (😅) to perform the fldmod by the constant 10^f coefficient. This brings 128-bit FD multiply to the same performance as 64-bit. :)
NHDaly
added a commit
that referenced
this pull request
Jun 13, 2024
Finally implements the fast-multiplication optimization from #45, but this time for 128-bit FixedDecimals! :) This is a follow-up to #93, which introduces an Int256 type for widemul. However, the fldmod still required 2 BigInt allocations. Now, this PR uses a custom implementation of the LLVM div-by-const optimization for (U)Int256, which briefly widens to Int512 (😅) to perform the fldmod by the constant 10^f coefficient. This brings 128-bit FD multiply to the same performance as 64-bit. :)
NHDaly
added a commit
that referenced
this pull request
Jun 13, 2024
Finally implements the fast-multiplication optimization from #45, but this time for 128-bit FixedDecimals! :) This is a follow-up to #93, which introduces an Int256 type for widemul. However, the fldmod still required 2 BigInt allocations. Now, this PR uses a custom implementation of the LLVM div-by-const optimization for (U)Int256, which briefly widens to Int512 (😅) to perform the fldmod by the constant 10^f coefficient. This brings 128-bit FD multiply to the same performance as 64-bit. :)
NHDaly
added a commit
that referenced
this pull request
Jun 13, 2024
Finally implements the fast-multiplication optimization from #45, but this time for 128-bit FixedDecimals! :) This is a follow-up to #93, which introduces an Int256 type for widemul. However, the fldmod still required 2 BigInt allocations. Now, this PR uses a custom implementation of the LLVM div-by-const optimization for (U)Int256, which briefly widens to Int512 (😅) to perform the fldmod by the constant 10^f coefficient. This brings 128-bit FD multiply to the same performance as 64-bit. :)
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We do not here explicitly introduce support for FD{BitIntegers.Int256}, though that should work out of the box both before and after this PR.
Rather, this PR uses a (U)Int256 under the hood to prevent allocations from Int128 widening to BigInt in FD operations.
Unfortunately,
remandmodon BitIntegers.Int256 still fall-back to a BigInt (see the note here), so this doesn't completely eliminate the BigInt allocs. But it does reduce them.This is a pretty small PR, but it should have a big impact on users of
FD{Int128}.Before:
After: