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UsageAnalyzer: Collect identifiers found in attributes as seeds

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This marks every identifier used within an attribute as seeds. The scenario
this avoids is functions referenced through attributes on unused tables or
record types (&default, &expire_func, ...) being dinged as unused as
that's rather confusing.

Also adds test for the above and a light smoke test into language/ as it
doesn't appear we had coverage here.

Closes #3122
This commit is contained in:
Arne Welzel 2023-07-12 12:19:48 +02:00
parent 3c7a52d0a7
commit ab388844bf
7 changed files with 139 additions and 0 deletions
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58
src/script_opt/UsageAnalyzer.cc
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@ -98,8 +98,60 @@ UsageAnalyzer::UsageAnalyzer(std::vector<FuncInfo>& funcs)
}
}
// Find all identifiers in attributes for seeding.
//
// General motivation: Dinging functions referenced from &default or &expire_func
// on tables or &default on record types is confusing when really the containing
// table/type is unused. Any IDs references from attributes are therefore
// implicitly used as seeds.
class AttrExprIdsCollector : public TraversalCallback
{
public:
TraversalCode PreAttr(const Attr* attr) override
{
++attr_depth;
return TC_CONTINUE;
}
TraversalCode PostAttr(const Attr* attr) override
{
--attr_depth;
return TC_CONTINUE;
}
TraversalCode PreType(const Type* t) override
{
if ( analyzed_types.count(t) > 0 )
return TC_ABORTSTMT;
analyzed_types.insert(t);
return TC_CONTINUE;
}
TraversalCode PreID(const ID* id) override
{
if ( ids.count(id) > 0 )
return TC_ABORTSTMT;
if ( attr_depth > 0 )
ids.insert(id);
id->GetType()->Traverse(this);
if ( auto& attrs = id->GetAttrs() )
attrs->Traverse(this);
return TC_CONTINUE;
}
int attr_depth = 0; // Are we in an attribute?
std::set<const detail::ID*> ids; // List of IDs found in attributes.
std::set<const Type*> analyzed_types; // Endless recursion avoidance.
};
void UsageAnalyzer::FindSeeds(IDSet& seeds) const
{
AttrExprIdsCollector attr_ids_collector;
for ( auto& gpair : global_scope()->Vars() )
{
auto& id = gpair.second;
@ -125,7 +177,13 @@ void UsageAnalyzer::FindSeeds(IDSet& seeds) const
// use it.
if ( id->IsExport() || id->ModuleName() == "GLOBAL" )
seeds.insert(id.get());
else
// ...otherwise, find all IDs referenced from attribute expressions
// found through this identifier.
id->Traverse(&attr_ids_collector);
}
seeds.insert(attr_ids_collector.ids.begin(), attr_ids_collector.ids.end());
}
const Func* UsageAnalyzer::GetFuncIfAny(const ID* id) const