================
@@ -556,8 +554,47 @@ class FactGeneratorVisitor : public
ConstStmtVisitor<FactGeneratorVisitor> {
return false;
}
+ void handleAssignment(const Expr *LHSExpr, const Expr *RHSExpr) {
+ // Find the underlying variable declaration for the left-hand side.
+ if (const auto *DRE_LHS =
+ dyn_cast<DeclRefExpr>(LHSExpr->IgnoreParenImpCasts())) {
+ markUseAsWrite(DRE_LHS);
+ if (const auto *VD_LHS = dyn_cast<ValueDecl>(DRE_LHS->getDecl()))
+ if (hasOrigin(VD_LHS->getType()))
+ // We are interested in assignments like `ptr1 = ptr2` or `ptr =
&var`
+ // LHS must be a pointer/reference type that can be an origin.
+ // RHS must also represent an origin (either another pointer/ref or
an
+ // address-of).
+ addAssignOriginFact(*VD_LHS, *RHSExpr);
+ }
+ }
+
+ // A DeclRefExpr is a use of the referenced decl. It is checked for
+ // use-after-free unless it is being written to (e.g. on the left-hand side
+ // of an assignment).
+ void handleUse(const DeclRefExpr *DRE) {
+ const auto *VD = dyn_cast<ValueDecl>(DRE->getDecl());
+ if (VD && hasOrigin(VD->getType())) {
+ UseFact *UF = FactMgr.createFact<UseFact>(DRE);
+ CurrentBlockFacts.push_back(UF);
+ assert(!UseFacts.contains(DRE));
+ UseFacts[DRE] = UF;
+ }
+ }
+
+ void markUseAsWrite(const DeclRefExpr *DRE) {
+ assert(UseFacts.contains(DRE));
+ UseFacts[DRE]->markAsWritten();
+ }
+
FactManager &FactMgr;
llvm::SmallVector<Fact *> CurrentBlockFacts;
+ // To distinguish between reads and writes for use-after-free checks, this
map
+ // stores the `UseFact` for each `DeclRefExpr`. We initially identify all
+ // `DeclRefExpr`s as "read" uses. When an assignment is processed, the use
+ // corresponding to the left-hand side is updated to be a "write", thereby
+ // exempting it from the check.
+ llvm::DenseMap<const DeclRefExpr *, UseFact *> UseFacts;
----------------
Xazax-hun wrote:
What is the plan for writes we have no DREs for? Like:
```
(cond ? a : b) = ptr;
```
https://github.com/llvm/llvm-project/pull/154316
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