Document the RemoveUnusedDeclarations pass. #548
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frontends/p4/unusedDeclarations.h
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| class RemoveAllUnusedDeclarations : public PassManager { | ||
| public: | ||
| explicit RemoveAllUnusedDeclarations(ReferenceMap* refMap, bool warn = false) { | ||
| CHECK_NULL(refMap); | ||
| std::set<const IR::Node*> *warned = nullptr; | ||
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| // TODO: The @warned set is discarded. Is it necessary, or can it be replaced |
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The set is not discarded, it is used as an argument for the RemoveUnusedDeclarations below.
It is the same set for all iterations of the PassRepeated, thus it cannot be replaced with a bool.
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Oh I see. This avoids issuing multiple warnings for the same unreferenced extern definition, which is the only thing that can both trigger a warning and persist across multiple rounds.
I'll remove the TODO and add a comment to this effect. Thanks for pointing it out.
frontends/p4/unusedDeclarations.h
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| * - IR::Type_StructLike | ||
| * | ||
| * If @warned is non-null, unused IR::P4Table and IR::Declaration_Instance | ||
| * nodes are stored in @warned if they are unused and removed by this pass. |
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In addition, a warning message is emitted only if the declaration was not previously in warned -- that is in fact the main point of warned -- to suppress duplicate warnings
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Thanks @mbudiu-vmw and @ChrisDodd. I updated the comments to (a) remove the TODO, which was wrong, and (b) clarify the behavior of the warning list. |
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…o make giveWarning() private, since it is only used inside the pass.
…O comment). Based on feedback from @mbudiu-vmw and @ChrisDodd.
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