[sil-generic-specializer] Avoid unlimited generic specialization of very deeply nested bound generic types #3504
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@rudkx @bob-wilson What do you think? Should we merge it as a short-time fix? Or should we better wait for now and then come up with a more principle way to fix this kind of issues? |
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Seems clever, and possibly good enough, but I wonder if the threshold is too high. Also, in the comment you say that Array<Array<Array>> is depth 3, but what is the maximum depth that we specialize too in the implementation of Array (which uses other parameterized types, etc.)? |
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@rudkx Before committing it, I discussed the threshold with @gribozavr to figure out what would be the safe bet. And we decided to go for 50. I agree that it is eventually too high, because on the stdlib and validation suite we never reach even a threshold of 10. I know it, because I did some debug printing and asked it to report any generic apply which has a bound generic argument of depth >= 10. |
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| static unsigned getBoundGenericDepth(Type t) { | ||
| unsigned Depth = 0; | ||
| if (auto BGT = dyn_cast<BoundGenericType>(t.getCanonicalTypeOrNull())) { |
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@swiftix The correct way of doing this is 't->getAs<BoundGenericType>()'
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@slavapestov Ah, yes. I keep forgetting it every time ;-)
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…ery deeply nested bound generic types The generic specialized would get out of control in certain cases and would not stop generating specializations of generic functions until it runs out of memory after a while. rdar://21260480
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[pull] swiftwasm from main
What's in this pull request?
Resolved bug number: (SR-)
rdar://21260480
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The generic specialized would get out of control in certain cases and would not stop generating specializations of generic functions until it runs out of memory after a while.