Java: Assume normal termination in post-dominance. #20163
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I've started dca with the only two queries using post-dominance: |
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Dca shows zero impact (as could be expected). |
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Pull Request Overview
This PR modifies Java's post-dominance calculation to assume normal termination rather than accounting for exceptions. This aligns Java with the shared CFG library approach and fixes a bug where exception handling was inconsistent due to elided exception edges in the CFG when no try-block is present.
- Changes post-dominance exit nodes from general
ExitNodetoNormalExitNodeonly - Updates test expectations to reflect the new post-dominance relationships
Reviewed Changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| java/ql/lib/semmle/code/java/controlflow/BasicBlocks.qll | Changes post-dominance calculation to use normal exit nodes only |
| java/ql/test-kotlin1/library-tests/controlflow/basic/strictPostDominance.expected | Updated test expectations for new post-dominance behavior |
| java/ql/test-kotlin2/library-tests/controlflow/basic/strictPostDominance.expected | Updated test expectations for new post-dominance behavior |
hvitved
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Aug 5, 2025
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This is a followup for #19885, which made this possible.
The concept of post-dominance may either assume normal termination of a callable, or try to account for exceptions. This PR switches Java to the former, which is in line with the shared CFG library. Indeed, trying to account for exceptions in post-dominance usually isn't what's desired, and it's also somewhat meaningless, since many potential exception edges are elided in the CFG if there's no enclosing try-block. As such, I'll consider this to be a bug-fix (and a somewhat minor one given that post-dominance is only rarely used).