[Mem2Reg] Skip load [take] of cast projections. #41751
Merged
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
Already, load [take]s of struct_element_addr|tuple_element_addr projections resulted in Mem2Reg bailing. Expand that to include load [take]s involving unchecked_addr_cast. To handle load [take]s of (struct|tuple)_element_addr projections, it would be necessary to replace the running value with a value obtained from the original product by recursive destructuring, replacing the value at the load [take]n address with undef, and then restructuring. To handle load [take]s of cast projections, it would be necessary to use unchecked_value_cast instead of unchecked_bitwise_cast. But we would need to still use unchecked_bitwise_cast in the case of load [copy] because otherwise we would lose the original value--unchecked_value_cast forwards ownership, and not all casts can be reversed (because they may narrow). For now, just bail out in the face of these complex load [take]s.
|
@swift-ci please test |
atrick
approved these changes
Mar 10, 2022
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Outdated suggestions cannot be applied.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.
Already,
load [take]s ofstruct_element_addr|tuple_element_addrprojections resulted in Mem2Reg bailing. Expand that to includeload [take]s involvingunchecked_addr_cast.To handle
load [take]s of(struct|tuple)_element_addrprojections, it would be necessary to replace the running value with a value obtained from the original product by recursive destructuring, replacing the value at theload [take]n address withundef, and then restructuring.To handle
load [take]s of cast projections, it would be necessary to useunchecked_value_castinstead ofunchecked_bitwise_cast. But we would need to still useunchecked_bitwise_castin the case ofload [copy]because otherwise we would lose the original value--unchecked_value_castforwards ownership, and not all casts can be reversed (because they may narrow).For now, just bail out in the face of these complex
load [take]s.