BUG, SIMD: Fix 64-bit/8-bit integer division by a scalar #20297
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
The multiplier factor that used for integer division wasn't correctly calculated due inaccurate implementation of the emulated version of intrinsic `_udiv128`.
…several data ranges
Same as 64-bit divistion, except quad wide divison leads to inaccurate multiplier in certain cases when the log2 of the divisor overflow to zero.
charris
added
00 - Bug
component: SIMD
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Backport of #20153.
This pull request fixes two bugs:
64-bit integer division by a scalar for both unsigned and signed division,
which was discovered by BUG: Bad SIMD integer
//on windows in numpy 1.21.2 #20025.It's only limited to old versions of msvc <= 2017, due to inaccurate
implementation of the emulated version for intrinsic
_udiv128,which leads to producing an inaccurate multiplier.
8-bit unsigned integer division, similar to the above except it is not limited to a certain compiler
and the inaccurate multiplier was caused due to wrong casting leads to perform quad division.
it can be triggered if the ceil(log2(divisor)) == 8.
closes #20025, #20168