Fix misoptimization in OptimizeHopToExecutor #41175
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@swift-ci please test |
DougGregor
approved these changes
Feb 3, 2022
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Build failed |
The problem is in `OptimizeHopToExecutor::collectActors`, which is causing `removeRedundantHopToExecutors` to drop the `hop_to_executor`. The issue is triggered by the order in which the Actors map is populated, and the reuse of a SILValue representing an executor. Suppose we have a function like this: ``` bb0: %7 = builtin "getCurrentExecutor"() : $Optional<Builtin.Executor> // ... cond_br %12, bb2, bb1 bb1: // ... hop_to_executor %7 : $Optional<Builtin.Executor> bb2: // ... hop_to_executor %7 : $Optional<Builtin.Executor> // ... hop_to_executor %28 : $MainActor ``` Since `collectActors` goes through each function's instructions top-down, and assigns to each unique SILValue an ID equal to the size of the Actors map prior to inserting the SILValue in the map, and we end up with the wrong actor IDs. This commit changes the ID numbering scheme to correct the issue.
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@swift-ci please smoke test and merge |
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random failure on Linux for: |
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@swift-ci please smoke test and merge |
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The problem is in
OptimizeHopToExecutor::collectActors, which iscausing
removeRedundantHopToExecutorsto drop thehop_to_executor. The issueis triggered by the order in which the Actors map is populated, and the reuse
of a SILValue representing an executor. Suppose we have a function like this:
Since
collectActorsgoes through each function's instructions top-down,and assigns to each unique SILValue an ID equal to the size of the Actors map
prior to inserting the SILValue in the map, and we end up with the wrong actor IDs.
This commit changes the ID numbering scheme to correct the issue.
Resolves rdar://88285600 / SR-15789