C++: Only propagate smallest/largest range bound in conditional expressions #18461
+38
−26
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
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Outdated suggestions cannot be applied.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.
This PR changes how bounds are propagated for the ternary operator.
Currently, for
c ? e1 : e2the union of the bounds fore1ande2are propagated. With this change the bounds are combined with the smallest/greatest (for lower bounds/upper bounds respectively) being propagated.Hence the number of bounds for
c ? e1 : e2changes from|e1| + |e2|to|e1| * |e2|. This is good when the number of bounds is 1 and worse otherwise. DCA will hopefully tell of if the overall impact is good or bad.