[CodeGen] Fix generating permute bytes from register pair when the initial values are undefined #74437
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
…es are undefined.
mmoadeli
changed the title
Artem-B
approved these changes
Jan 10, 2024
Artem-B
approved these changes
Jan 16, 2024
jsji
pushed a commit
to intel/llvm
that referenced
this pull request
Jan 19, 2024
#11840 is resolved by usptreaming the fix in #12068 to llvm/llvm-project#74437.
justinfargnoli
pushed a commit
to justinfargnoli/llvm-project
that referenced
this pull request
Jan 28, 2024
…ial values are undefined (llvm#74437) When generating the permute bytes for the prmt instruction, the existence of an undefined initial value initialises the int32 that holds the mask with all 1's (0xFFFFFFFF). That initialization subsequently leads to complications during the subsequent OR operation, leading to inaccuracies in populating mask values for the following bytes. Consequently, the final value persists as a constant -1, irrespective of the actual mask values that succeed the initial set value.
This was referenced Mar 6, 2024
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Outdated suggestions cannot be applied.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.
When generating the permute bytes for the prmt instruction, the existence of an undefined initial value initialises the int32 that holds the mask with all 1's (0xFFFFFFFF). That initialization subsequently leads to complications during the subsequent OR operation, leading to inaccuracies in populating mask values for the following bytes. Consequently, the final value persists as a constant -1, irrespective of the actual mask values that succeed the initial set value.