verilog: fix parser "if" memory errors. #5193
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
Fix buggy memory allocation introduced in YosysHQ#5152: 1) clean up ast_stack to reflect AST node rearrangement when necessary, to avoid dangling pointer; 2) call free_attr() on unused attribute list when no new syntax node is created, to avoid leaking it.
zachjs
approved these changes
Jun 23, 2025
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Outdated suggestions cannot be applied.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.
Fix buggy memory allocation introduced in #5152:
ast_stackto reflect AST node rearrangement when necessary, to avoid dangling pointer;free_attr()on unused attribute list when no new syntax node is created, to avoid leaking it.What are the reasons/motivation for this change?
To fix the allocation bug discussed in #5152 and #5189.
This also assists #5180, which was blocked by this bug.
Explain how this is achieved.
Commit 370d587 handles an
else ifbranch within aunique ifby replacing the currentAST_COND/AST_DEFAULT/AST_BLOCK"else" construction with a newAST_COND/(expr)/AST_BLOCKwithin the originalAST_CASE. However, it mistakenly left a dangling reference to the original (now orphaned) structure reachable viaast_stack. This commit updates theast_stackstate to point to the replacement instead of the orphan.If applicable, please suggest to reviewers how they can test the change.
Build with
clangandSANITIZER=address. Thenmake test(in particulartests/verilog/unique_if_enc.ys) should succeed. (The test case in #5152 (comment) is a smaller example triggering the same logic.)