[release/9.0-rc1] JIT: fix unused operand marking in LowerHWIntrinsicTernaryLogic #106574
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
![github-actions[bot]](https://avatars.githubusercontent.com/in/15368?s=60&v=4){kind=small}
In `LowerHWIntrinsicTernaryLogic` we do some operand swapping and replacing, and were not accounting for this when marking operands as unused. Fixes #106480.
dotnet-issue-labeler
bot
added
the
area-CodeGen-coreclr
|
Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
|
@tannergooding PTAL |
This was referenced Aug 17, 2024
Closed
Closed
tannergooding
approved these changes
Aug 18, 2024
|
@carlossanlop are we still considering rc1 fixes? |
jeffschwMSFT
approved these changes
Aug 19, 2024
It seems so. We just got two bad build breaks fixed today. So I guess we can take this today too. Has this been approved by Tactics? @AndyAyersMS @jeffschwMSFT |
carlossanlop
added
Servicing-approved
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
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Outdated suggestions cannot be applied.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 #106555 to release/9.0-rc1
/cc @AndyAyersMS
Customer Impact
Found by Antigen (internal exploratory test generator).
Certain uses of AVX512F's Ternary Logic will lead to silent bad code generation.
Regression
Introduced fairly recently, in #104517.
Testing
The fix was validated on the Antigen test case, and that case is now included in our regression suite.
We likely need to pay more attention in reviews and testing when considering code where operands can be swapped, as it's easy to lose track of which one is which.
Risk
Low. Only impacts a handful of AVX512-specific intrinsics. But note TernaryLogic lowers to a powerful new instruction (
vpternlog{d,q}) and we are increasingly shaping our IR to take advantage of it, when running on AVX-512 hardware.IMPORTANT: If this backport is for a servicing release, please verify that:
The PR target branch is
release/X.0-staging, notrelease/X.0.If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.