release/21.x: [MachinePipeliner] Limit the number of stores in BB (#154940) #162639
+25
−0
Conversation
This file contains hidden or 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 dependency analysis in MachinePipeliner checks dependencies for every pair of store instructions in the target basic block. This means the time complexity of the analysis is `O(N^2)`, where `N` is the number of store instructions. Therefore, compilation time can become significantly long when there are too many store instructions. To mitigate it, this patch introduces logic to count the number of store instructions at the beginning of the pipeliner and bail out if it exceeds the threshold. The default value if the threshold should be large enough. Thus, in most practical cases where the pipeliner is beneficial, this patch should not cause any performance regression. Related issue: llvm#150262 (cherry picked from commit 22b79fb)
|
@aankit-ca What do you think about merging this PR to the release branch? |
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Outdated suggestions cannot be applied.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 22b79fb
Requested by: @kasuga-fj