[simplify-cfg] Add a visitedBlocks set to hasSameUltimateSuccessor to prevent infinite loops. #27468
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…nches for testing purposes I am going to use this in a subsequent commit to make sure we do not infinite loop upon a test case. rdar://55861081 (cherry picked from commit fab7752)
… prevent infinite loops. Previously, we were not handling properly blocks that we could visit multiple times. In this commit, I added a SmallPtrSet to ensure that we handle all of the same cases that we handled previously. The key reason that we want to follow this approach rather than something else is that the previous algorithm on purpose allowed for side-entrances from other checks since often times when we have multiple checks, all of the .none branches funnel together into a single ultimate block. This can be seen by the need of this code to support the test two_chained_calls in simplify_switch_enum_objc.sil. rdar://55861081 (cherry picked from commit aa00865)
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@swift-ci test |
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@airspeedswift can I get a +1 here? |
airspeedswift
approved these changes
Oct 3, 2019
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Thanks! |
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[simplify-cfg] Add a visitedBlocks set to hasSameUltimateSuccessor to prevent infinite loops.
Previously, we were not handling properly blocks that we could visit multiple
times. In this commit, I added a SmallPtrSet to ensure that we handle all of the
same cases that we handled previously.
The key reason that we want to follow this approach rather than something else
is that the previous algorithm on purpose allowed for side-entrances from other
checks since often times when we have multiple checks, all of the .none branches
funnel together into a single ultimate block.
This can be seen by the need of this code to support the test two_chained_calls
in simplify_switch_enum_objc.sil.
rdar://55861081
(cherry picked from commit aa00865)