[sil-mandatory-inliner] Decrease the compile time #4635
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The inlining algorithm was rescanning the whole basic block after inlining a call, which resulted in O(N^2) time complexity. In some pathological cases like e.g. huge basic blocks with many thousands of calls this would lead to very long compile times which could takes hours to finish. This change improves compile times by avoiding the rescanning of basic blocks containing the call which was inlined. rdar://27818830
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@swift-ci Please test |
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Build failed |
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I think that the Linux failure is unrelated. It seems to be related to multi-threading. |
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It is. This has been hitting other patches as well. |
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––– CCC Information –––
• Explanation: It is a compile-time speed improvement.
• Scope of Issue: Get rid of O(N^2) behavior in the mandatory inliner
• Origination: rdar://problem/27301540
• Risk: Very low. The patch has been on the master for a week without any regressions or correctness issues.
• Reviewed By: Bob Wilson
• Testing: Verified locally and using a CI @please test
• Directions for QA: Check that test files reported in the radar are now compiled rather quickly instead of taking many hours.
Detailed description
The inlining algorithm was rescanning the whole basic block after inlining a call, which resulted in O(N^2) time complexity. In some pathological cases like e.g. huge basic blocks with many thousands of calls this would lead to very long compile times which could takes hours to finish.
This change improves compile times by avoiding the rescanning of basic blocks containing the call which was inlined.
rdar://27818830