vasm-graph-color: dedupe phijmp operands before coloring #9685
+54
−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
Deduplicate duplicate phijmp sources so each phi operand has its own SSA name. When two phi operands pointed at the same penalty vector, biasing one register also penalized the other, so we almost never picked a single physreg for the phidef/phijmp chain. That produced extra copy/copy2s (especially painful on AArch64 where there’s no xchg). Splitting duplicates during preparation keeps the penalty data independent and reduces those redundant moves.
|
@facebook-github-bot has imported this pull request. If you are a Meta employee, you can view this in D88385561. (Because this pull request was imported automatically, there will not be any future comments.) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
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Outdated suggestions cannot be applied.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.
Deduplicate duplicate phijmp sources so each phi operand has its own SSA name. When two phi operands pointed at the same penalty vector, biasing one register also penalized the other, so we almost never picked a single physreg for the phidef/phijmp chain. That produced extra copy/copy2s (especially painful on AArch64 where there’s no xchg). Splitting duplicates during preparation keeps the penalty data independent and reduces those redundant moves.