compiler: Limit depth of sharing state tree #8567
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CT Test Results 2 files 324 suites 11m 2s ⏱️ Results for commit 28d0a97. ♻️ This comment has been updated with latest results. To speed up review, make sure that you have read Contributing to Erlang/OTP and that all checks pass. See the TESTING and DEVELOPMENT HowTo guides for details about how to run test locally. Artifacts// Erlang/OTP Github Action Bot |
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Thanks! Looks good to me. Can you rebase onto the |
With OTP 27.0 the xmerl tests showed a markedly increased run-time. Profiling pointed to beam_ssa_ss:prune/2 as the culprit. It turns out that if there are long value derivation chains which are extended one element at a time (such as in the ss_depth_limit.erl test-case in this patch), the effective time complexity of prune will be O(n^2) where n is the number of elements in the chain. By limiting the depth of the sharing state tree, we can avoid the drastically increased run-times for the alias analysis. This is a stop-gap fix until the alias analysis can be improved to avoid this pit-fall.
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Rebased onto |
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Thanks! Added to our daily builds. |
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With OTP 27.0 the xmerl tests showed a markedly increased run-time. Profiling pointed to beam_ssa_ss:prune/2 as the culprit. It turns out that if there are long value derivation chains which are extended one element at a time (such as in the ss_depth_limit.erl test-case in this patch), the effective time complexity of prune will be O(n^2) where n is the number of elements in the chain.
By limiting the depth of the sharing state tree, we can avoid the drastically increased run-times for the alias analysis. This is a stop-gap fix until the alias analysis can be improved to avoid this pit-fall.