================
@@ -956,42 +958,112 @@ static llvm::Value
*getArrayIndexingBound(CodeGenFunction &CGF,
return nullptr;
}
-const Expr *
-CodeGenFunction::BuildCountedByFieldExpr(const Expr *Base,
- const ValueDecl *CountedByVD) {
+namespace {
+
+/// \p MemberExprBaseVisitor returns the base \p DeclRefExpr of a field access.
+class MemberExprBaseVisitor
+ : public StmtVisitor<MemberExprBaseVisitor, Expr *> {
+ const RecordDecl *ExpectedRD;
+
+ bool IsExpectedRecordDecl(const Expr *E) const {
+ QualType Ty = E->getType();
+ if (Ty->isPointerType())
+ Ty = Ty->getPointeeType();
+ return ExpectedRD == Ty->getAsRecordDecl();
+ }
+
+public:
+ MemberExprBaseVisitor(const RecordDecl *ExpectedRD)
+ : ExpectedRD(ExpectedRD) { }
+
+
//===--------------------------------------------------------------------===//
+ // Visitor Methods
+
//===--------------------------------------------------------------------===//
+
+ // Note: if we build C++ support for counted_by, then we'll have to handle
+ // horrors like this:
+ //
+ // struct S {
+ // int x, y;
+ // int blah[] __attribute__((counted_by(x)));
+ // } s;
+ //
+ // int foo(int index, int val) {
+ // int (S::*IHatePMDs)[] = &S::blah;
+ // (s.*IHatePMDs)[index] = val;
+ // }
+
+ Expr *Visit(Expr *E) {
+ return StmtVisitor<MemberExprBaseVisitor, Expr *>::Visit(E);
+ }
+
+ Expr *VisitCastExpr(CastExpr *E) {
+ return IsExpectedRecordDecl(E) ? E : Visit(E->getSubExpr());
+ }
+ Expr *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
+ return IsExpectedRecordDecl(E) ? E : nullptr;
+ }
+ Expr *VisitDeclRefExpr(DeclRefExpr *E) {
+ return IsExpectedRecordDecl(E) ? E : nullptr;
+ }
+ Expr *VisitMemberExpr(MemberExpr *E) {
+ Expr *Res = Visit(E->getBase());
+ return !Res && IsExpectedRecordDecl(E) ? E : Res;
+ }
+ Expr *VisitParenExpr(ParenExpr *E) {
+ return IsExpectedRecordDecl(E) ? E : Visit(E->getSubExpr());
+ }
+
+ Expr *VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
+ return Visit(E->getBase());
+ }
+ Expr *VisitImplicitCastExpr(CastExpr *E) { return Visit(E->getSubExpr()); }
+ Expr *VisitUnaryOperator(UnaryOperator *E) { return Visit(E->getSubExpr()); }
+};
+
+} // end anonymous namespace
+
+llvm::Value *
+CodeGenFunction::EmitCountedByFieldExpr(const Expr *Base,
+ const ValueDecl *CountedByVD) {
+ const DeclContext *DC = CountedByVD->getLexicalDeclContext();
+ const auto *CountedByRD = cast<RecordDecl>(DC);
+
// Find the outer struct expr (i.e. p in p->a.b.c.d).
- Expr *CountedByExpr = const_cast<Expr *>(Base)->IgnoreParenImpCasts();
-
- // Work our way up the expression until we reach the DeclRefExpr.
- while (!isa<DeclRefExpr>(CountedByExpr))
- if (const auto *ME = dyn_cast<MemberExpr>(CountedByExpr))
- CountedByExpr = ME->getBase()->IgnoreParenImpCasts();
-
- // Add back an implicit cast to create the required pr-value.
- CountedByExpr = ImplicitCastExpr::Create(
- getContext(), CountedByExpr->getType(), CK_LValueToRValue, CountedByExpr,
- nullptr, VK_PRValue, FPOptionsOverride());
-
- if (const auto *IFD = dyn_cast<IndirectFieldDecl>(CountedByVD)) {
- // The counted_by field is inside an anonymous struct / union. The
- // IndirectFieldDecl has the correct order of FieldDecls to build this
- // easily. (Yay!)
- for (NamedDecl *ND : IFD->chain()) {
- auto *VD = cast<ValueDecl>(ND);
- CountedByExpr =
- MemberExpr::CreateImplicit(getContext(), CountedByExpr,
- CountedByExpr->getType()->isPointerType(),
- VD, VD->getType(), VK_LValue,
OK_Ordinary);
- }
- } else {
- CountedByExpr = MemberExpr::CreateImplicit(
- getContext(), const_cast<Expr *>(CountedByExpr),
- CountedByExpr->getType()->isPointerType(),
- const_cast<ValueDecl *>(CountedByVD), CountedByVD->getType(),
VK_LValue,
- OK_Ordinary);
+ Expr *CountedByExpr =
+ MemberExprBaseVisitor(CountedByRD).Visit(const_cast<Expr *>(Base));
+ if (!CountedByExpr)
+ return nullptr;
+
+ llvm::Value *Res = nullptr;
+ if (CountedByExpr->getType()->isPointerType())
+ Res = EmitPointerWithAlignment(CountedByExpr).getPointer();
----------------
efriedma-quic wrote:
Oo, I should have spotted this earlier. EmitPointerWithAlignment/EmitLValue is
going to repeat any side-effects of the expression in question. You can't emit
an expression twice, in general.
So for the array bounds sanitizer case, I think this needs to be integrated a
bit more tightly with the expression emission. (Not sure about the object_size
case.)
https://github.com/llvm/llvm-project/pull/73730
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