https://github.com/usx95 created
https://github.com/llvm/llvm-project/pull/148222
None
>From 14a9c8b50df11ce48ce15d0fbe29568b3e23b5a6 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <u...@google.com>
Date: Fri, 11 Jul 2025 11:11:47 +0000
Subject: [PATCH] [LifetimeSafety] Add expired loans analysis
---
clang/lib/Analysis/LifetimeSafety.cpp | 140 ++++++++++++++++++++++++++
1 file changed, 140 insertions(+)
diff --git a/clang/lib/Analysis/LifetimeSafety.cpp
b/clang/lib/Analysis/LifetimeSafety.cpp
index e72192aa92c1a..88ec70d000d2c 100644
--- a/clang/lib/Analysis/LifetimeSafety.cpp
+++ b/clang/lib/Analysis/LifetimeSafety.cpp
@@ -735,6 +735,142 @@ class LifetimeDataflow {
}
};
+// ========================================================================= //
+// Expired Loans Analysis
+// ========================================================================= //
+
+/// The lattice for tracking expired loans. It is a set of loan IDs.
+struct ExpiredLattice {
+ LoanSet Expired;
+
+ ExpiredLattice() = default;
+ explicit ExpiredLattice(LoanSet S) : Expired(S) {}
+
+ bool operator==(const ExpiredLattice &Other) const {
+ return Expired == Other.Expired;
+ }
+ bool operator!=(const ExpiredLattice &Other) const {
+ return !(*this == Other);
+ }
+
+ /// Computes the union of two lattices.
+ ExpiredLattice join(const ExpiredLattice &Other,
+ LoanSet::Factory &Factory) const {
+ LoanSet JoinedSet = Expired;
+ for (LoanID LID : Other.Expired)
+ JoinedSet = Factory.add(JoinedSet, LID);
+ return ExpiredLattice(JoinedSet);
+ }
+
+ void dump(llvm::raw_ostream &OS) const {
+ OS << "ExpiredLattice State:\n";
+ if (Expired.isEmpty())
+ OS << " <empty>\n";
+ for (const LoanID &LID : Expired)
+ OS << " Loan " << LID << " is expired\n";
+ }
+};
+
+/// Transfer function for the expired loans analysis.
+class ExpiredLoansTransferer {
+ FactManager &AllFacts;
+ LoanSet::Factory &SetFactory;
+
+public:
+ explicit ExpiredLoansTransferer(FactManager &F, LoanSet::Factory &SF)
+ : AllFacts(F), SetFactory(SF) {}
+
+ /// Computes the exit state of a block by applying all its facts sequentially
+ /// to a given entry state.
+ ExpiredLattice transferBlock(const CFGBlock *Block,
+ ExpiredLattice EntryState) {
+ ExpiredLattice BlockState = EntryState;
+ llvm::ArrayRef<const Fact *> Facts = AllFacts.getFacts(Block);
+
+ for (const Fact *F : Facts) {
+ BlockState = transferFact(BlockState, F);
+ }
+ return BlockState;
+ }
+
+private:
+ ExpiredLattice transferFact(ExpiredLattice In, const Fact *F) {
+ if (const auto *EF = F->getAs<ExpireFact>())
+ return ExpiredLattice(SetFactory.add(In.Expired, EF->getLoanID()));
+
+ if (const auto *IF = F->getAs<IssueFact>())
+ return ExpiredLattice(SetFactory.remove(In.Expired, IF->getLoanID()));
+
+ return In;
+ }
+};
+
+/// Dataflow analysis driver for tracking expired loans.
+class ExpiredLoansAnalysis {
+ const CFG &Cfg;
+ AnalysisDeclContext &AC;
+ LoanSet::Factory SetFactory;
+ ExpiredLoansTransferer Xfer;
+
+ llvm::DenseMap<const CFGBlock *, ExpiredLattice> BlockEntryStates;
+ llvm::DenseMap<const CFGBlock *, ExpiredLattice> BlockExitStates;
+
+public:
+ ExpiredLoansAnalysis(const CFG &C, FactManager &FS, AnalysisDeclContext &AC)
+ : Cfg(C), AC(AC), Xfer(FS, SetFactory) {}
+
+ void run() {
+ llvm::TimeTraceScope TimeProfile("Expired Loans Analysis");
+ ForwardDataflowWorklist Worklist(Cfg, AC);
+ const CFGBlock *Entry = &Cfg.getEntry();
+ BlockEntryStates[Entry] = ExpiredLattice(SetFactory.getEmptySet());
+ Worklist.enqueueBlock(Entry);
+ while (const CFGBlock *B = Worklist.dequeue()) {
+ ExpiredLattice EntryState = getEntryState(B);
+ ExpiredLattice ExitState = Xfer.transferBlock(B, EntryState);
+ BlockExitStates[B] = ExitState;
+
+ for (const CFGBlock *Successor : B->succs()) {
+ auto SuccIt = BlockEntryStates.find(Successor);
+ ExpiredLattice OldSuccEntryState = (SuccIt != BlockEntryStates.end())
+ ? SuccIt->second
+ : ExpiredLattice{};
+ ExpiredLattice NewSuccEntryState =
+ OldSuccEntryState.join(ExitState, SetFactory);
+ if (SuccIt == BlockEntryStates.end() ||
+ NewSuccEntryState != OldSuccEntryState) {
+ BlockEntryStates[Successor] = NewSuccEntryState;
+ Worklist.enqueueBlock(Successor);
+ }
+ }
+ }
+ }
+
+ void dump() const {
+ llvm::dbgs() << "==========================================\n";
+ llvm::dbgs() << " Expired Loans Results:\n";
+ llvm::dbgs() << "==========================================\n";
+ const CFGBlock &B = Cfg.getExit();
+ getExitState(&B).dump(llvm::dbgs());
+ }
+
+ ExpiredLattice getEntryState(const CFGBlock *B) const {
+ auto It = BlockEntryStates.find(B);
+ if (It != BlockEntryStates.end()) {
+ return It->second;
+ }
+ return ExpiredLattice(SetFactory.getEmptySet());
+ }
+
+ ExpiredLattice getExitState(const CFGBlock *B) const {
+ auto It = BlockExitStates.find(B);
+ if (It != BlockExitStates.end()) {
+ return It->second;
+ }
+ return ExpiredLattice(SetFactory.getEmptySet());
+ }
+};
+
// ========================================================================= //
// TODO: Analysing dataflow results and error reporting.
// ========================================================================= //
@@ -762,5 +898,9 @@ void runLifetimeSafetyAnalysis(const DeclContext &DC, const
CFG &Cfg,
LifetimeDataflow Dataflow(Cfg, FactMgr, AC);
Dataflow.run();
DEBUG_WITH_TYPE("LifetimeDataflow", Dataflow.dump());
+
+ ExpiredLoansAnalysis ExpiredAnalysis(Cfg, FactMgr, AC);
+ ExpiredAnalysis.run();
+ DEBUG_WITH_TYPE("ExpiredLoans", ExpiredAnalysis.dump());
}
} // namespace clang
_______________________________________________
llvm-branch-commits mailing list
llvm-branch-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
