================
@@ -1051,6 +1052,145 @@ CodeGenFunction::emitFlexibleArrayMemberSize(const Expr
*E, unsigned Type,
return Builder.CreateSelect(Cmp, Res, ConstantInt::get(ResType, 0,
IsSigned));
}
+namespace {
+
+/// \p StructBaseExpr returns the base \p Expr with a structure or union type.
+struct StructBaseExpr : public ConstStmtVisitor<StructBaseExpr, const Expr *> {
+ StructBaseExpr() = default;
+
+
//===--------------------------------------------------------------------===//
+ // Visitor Methods
+
//===--------------------------------------------------------------------===//
+
+ const Expr *VisitStmt(const Stmt *S) { return nullptr; }
+
+ const Expr *Visit(const Expr *E) {
+ QualType Ty = E->getType();
+ if (Ty->isStructureType() || Ty->isUnionType())
+ return E;
+
+ return ConstStmtVisitor<StructBaseExpr, const Expr *>::Visit(E);
+ }
+
+ const Expr *VisitDeclRefExpr(const DeclRefExpr *E) { return E; }
+
+ const Expr *VisitMemberExpr(const MemberExpr *E) {
+ return Visit(E->getBase());
+ }
+ const Expr *VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
+ return Visit(E->getBase());
+ }
+ const Expr *VisitCastExpr(const CastExpr *E) {
+ return Visit(E->getSubExpr());
+ }
+ const Expr *VisitParenExpr(const ParenExpr *E) {
+ return Visit(E->getSubExpr());
+ }
+ const Expr *VisitUnaryAddrOf(const clang::UnaryOperator *E) {
+ return Visit(E->getSubExpr());
+ }
+ const Expr *VisitUnaryDeref(const clang::UnaryOperator *E) {
+ return Visit(E->getSubExpr());
+ }
----------------
zygoloid wrote:
Looking through both casts and dereferences seems like it won't be correct:
```
struct A { int ***p; } a;
int n = __builtin_dynamic_object_size(***a.p, 0);
```
... looks like it'll base the result on the size of `A`, which is unrelated.
I think you should be more conservative about the kinds of casts you'll walk
through here: bitcasts and pointer casts seem potentially OK to step through,
but things like lvalue-to-rvalue conversions will be problematic.
But looking at what you're doing with this below, I think it might be possible
to avoid doing this walk entirely.
https://github.com/llvm/llvm-project/pull/80256
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