Avoid optimization that beam_validator might consider unsafe #7330
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Eliminating a repeated `=:=` test can result in code that beam_validator doesn't consider safe. This commit makes the optimization keep the `=:=` if it seems to be significant, that is, if one or both operands will gain type information from it. That makes it possible to compile code from erlang#6599 such as: f(X, X) when is_integer(X) -> ok; f(Y, Y = #{}) -> Y#{ok := ok}. (Six other examples from erlang#6599 can now also be compiled.) Running `scripts/diffable` shows that this fix prevented the optimization in 14 modules (out of about 1000). Closes erlang#6599
CT Test Results 2 files 296 suites 22m 40s ⏱️ For more details on these failures, see this check. Results for commit a99d48f. ♻️ 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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Eliminating a repeated
=:=test can result in code thatbeam_validatordoesn't consider safe. This pull request makes the optimization keep=:=if it seems to be significant, that is, if one or both operands will gain type information from it.That makes it possible to compile code from #6599 such as:
(Six other examples from #6599 can now also be compiled.)
Running
scripts/diffableshows that this fix prevented the optimization in 14 modules (out of about 1000).Closes #6599 (the examples that were not fixed by this PR will be transferred to a new issue)