ctable: fix power-of-2 issue #1362
Merged
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
LuaJIT dislikes pointer subtractions when the size of the pointed-to objects is not a power of two, which leads to trace aborts. ctable suffers from this problem. The patch pads the cdata type used as entry for the table to the next power of two. We also disable tail-call optimization for functions that end with a call to a built-in, which also causes trace aborts in certain cases.
Merged
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Outdated suggestions cannot be applied.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.
I have brought this up in issue #1207, which is still open. I propose this fix at least as an interim solution until RaptorJIT lands (provided it will contain the fix proposed by @lukego).
Removal of two tail-call optimizations is also part of this PR. I found that this reduces trace aborts in my ipfix app some time ago. I'm not sure if we have converged on a common strategy to deal with this sort of problem, so this could be debatable.