Hidden field access and debugging features #108
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
Added an `extra_assert` feature which enables `extra_assert!` macros in release builds. Added the `immix_stress_copying` feature which enables the feature of the same name in `mmtk-core`. Added the `is_mmtk_object_safe` function which rejects against 0 and unaligned addresses before calling `is_mmtk_object`.
This ensures we access the hidden header in a uniform way, preventing mistakes such as forgetting to masking out other bits.
Enable extra assertions in release build when running CI tests. This will help us catch additional dangling pointer bugs.
In the `ruby` repo, we encapsulated the access to the hidden field, and disabled the code path to re-embedding "heap" arrays and strings.
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Outdated suggestions cannot be applied.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.
The main part of this PR is fixing a bug when accessing the hidden field. Previously, when loading the payload size from the hidden field before the object, it didn't mask out the
HAS_MOVED_GIVTBLflag, resulting in wrong object sizes. This PR fixes that. In bothmmtk-rubyandrubyrepos, we encapsulate the access to the hidden field in dedicated functions and make sure the bit masks are applied.In the
rubyrepo, we also disable the code paths that result in re-embedding "heap" arrays and strings, because that is a source of dangling pointer bugs.In the
mmtk-rubyrepo, we introduced theextra_assert!macro which can be enabled by the "extra_assert" Cargo feature even in release builds. We also introduced a feature for stressing Immix collectors and a saferis_mmtk_object_safefunction.