C++: Remove big-step relation in flow-through code#3857
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aschackmull merged 2 commits intogithub:masterfrom Jul 1, 2020
Merged
C++: Remove big-step relation in flow-through code#3857aschackmull merged 2 commits intogithub:masterfrom
aschackmull merged 2 commits intogithub:masterfrom
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This relation was originally introduced to improve performance but may no longer be necessary. The `localFlowStepPlus` predicate had an explosion of tuples on oneapi-src/oneDNN for C++.
In this non-linear recursion, a `#prev` relation was joined earlier than the `#prev_delta` relation. As a result, each iteration of the predicate processes every tuple from previous iterations. This quadratic behavior caused severe slowdowns on oneapi-src/oneDNN.
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aschackmull
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Jul 1, 2020
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hvitved
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Java as well, those two results can for some reason not be matched, so they show up as removed and re-introduced in every single Java-Differences. |
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The first commit makes it feasible to run C++ IR data-flow queries on oneapi-src/oneDNN, and the second makes it fast.
The second commit works around a join order problem that I've reported as https://github.com/github/codeql-coreql-team/issues/453.
I'll take this PR out of draft mode if *-Differences show no performance regressions.