Reapply "Fix open world public types" (#8802)#8810
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This reverts commit 9e3b947. Beyond reapplying the original commit, this adds special handling when `func` is exposed so that we avoid considering function types used only to declare unreferenced functions public. This avoids an assertion failure in MinimizeRecGroups when a previous pass like DAE optimizes an unreferenced function's type to differ from a public function type only by e.g. the exactness of a reference when custom descriptors is disabled. The assertion in MinimizeRecGroups is checking that all public types are distinguishable from each other given the enabled feature set. This is something we enforce when parsing input modules, so it makes sense to keep as an invariant of the IR. The change to consider types used only for unreferenced functions private lets us maintain that invariant without giving up optimization power unnecessarily.
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Still working through additional fuzz bugs on this. Marking as draft for now. |
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Fuzzer seems happy enough now, although I'll continue running it to see if anything else turns up. |
stevenfontanella
approved these changes
Jun 15, 2026
| // Find functions types that are used only in the declarations of | ||
| // unreferenced functions. | ||
| std::unordered_map<HeapType, Index> unreferencedCount; | ||
| for (auto& [func, referenced] : referencedFuncs) { |
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nit: let's use const for these loop variables to make it clearer to read? ditto below
| bool newType = false; | ||
| if (auto it = seenSigs.find(sig); it != seenSigs.end()) { | ||
| info.info[it->second].useCount += count; | ||
| sigInfo = &info.info[it->second]; |
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nit: it looks like we expect the lookup to succeed here, is that right? If so, let's use .at() instead to convey the intent better and fail loudly if the assumption is wrong?
| // exposure is upgraded, we re-push it to the worklist to update the | ||
| // propagation to related types. | ||
| auto markPublic = [&](HeapType type, Exposure state) { | ||
| auto [it, inserted] = exposures.insert({type, state}); |
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nit: looks like we can do try_emplace to avoid a move?
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This reverts commit 9e3b947.
Beyond reapplying the original commit, this adds special handling when
funcis exposed so that function types used only to declare unreferenced functions or for control flow are not considered public. Type identity does not matter and does not need to be preserved in these cases. This avoids an assertion failure in MinimizeRecGroups when control flow types or unreferenced function types differ from public types only in exactness when custom descriptors is disabled. This can happen as a result of optimizations such as DAE, which are free to change the types of unreferenced functions.Fixes #8718, #8798, #8799.