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release/20.x: Reduce memory usage in AST parent map generation by lazily checking if nodes have been seen (#129934) #131209

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Merged
merged 1 commit into from
Mar 17, 2025
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release/20.x: Reduce memory usage in AST parent map generation by lazily checking if nodes have been seen (#129934) #131209

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17 changes: 11 additions & 6 deletions clang/lib/AST/ParentMapContext.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,10 +12,11 @@
//===----------------------------------------------------------------------===//

#include "clang/AST/ParentMapContext.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/Decl.h"
#include "clang/AST/Expr.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/TemplateBase.h"
#include "llvm/ADT/SmallPtrSet.h"

using namespace clang;

Expand Down Expand Up @@ -69,17 +70,21 @@ class ParentMapContext::ParentMap {
for (; N > 0; --N)
push_back(Value);
}
bool contains(const DynTypedNode &Value) {
return Seen.contains(Value);
bool contains(const DynTypedNode &Value) const {
const void *Identity = Value.getMemoizationData();
assert(Identity);
return Dedup.contains(Identity);
}
void push_back(const DynTypedNode &Value) {
if (!Value.getMemoizationData() || Seen.insert(Value).second)
const void *Identity = Value.getMemoizationData();
if (!Identity || Dedup.insert(Identity).second) {
Items.push_back(Value);
}
}
llvm::ArrayRef<DynTypedNode> view() const { return Items; }
private:
llvm::SmallVector<DynTypedNode, 2> Items;
llvm::SmallDenseSet<DynTypedNode, 2> Seen;
llvm::SmallVector<DynTypedNode, 1> Items;
llvm::SmallPtrSet<const void *, 2> Dedup;
};

/// Maps from a node to its parents. This is used for nodes that have
Expand Down
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