================
@@ -1062,6 +1063,159 @@ CodeGenFunction::emitFlexibleArrayMemberSize(const Expr
*E, unsigned Type,
return Builder.CreateSelect(Cmp, Res, ConstantInt::get(ResType, 0,
IsSigned));
}
+namespace {
+
+class ObjectSizeVisitor
+ : public ConstStmtVisitor<ObjectSizeVisitor, const Expr *> {
+ bool SkipASE;
+
+public:
+ ObjectSizeVisitor(bool SkipASE = false) : SkipASE(SkipASE) {}
+
+ const Expr *Visit(const Expr *E) {
+ return ConstStmtVisitor<ObjectSizeVisitor, const Expr *>::Visit(E);
+ }
+
+ const Expr *VisitStmt(const Stmt *S) { return nullptr; }
+
+ const Expr *VisitDeclRefExpr(const DeclRefExpr *E) { return E; }
+ const Expr *VisitMemberExpr(const MemberExpr *E) { return E; }
+ const Expr *VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
+ return SkipASE ? Visit(E->getBase()) : E;
+ }
+
+ 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());
----------------
bwendling wrote:
My knowledge of the front-end's architecture isn't perfect, but it seems like
supporting that type of aliasing in the front-end isn't easy. For your example,
the code reverts to using the `llvm.objectsize` intrinsic on the result of
`EmitScalarExpr(p)`. This can be seen as a deficiency, but according to others
it's "acceptable" to return such in this case. I intend to expand the use of
this function with future changes, where it may be possible to support this
type of aliasing. But we'll always have issues with things like:
```c
unsigned __attribute__((always_inline)) foo(void *p) {
return __builtin_dynamic_object_size(p, 1);
}
void bar(int y) {
int *x[10];
foo((void *)x[y]);
}
```
because we don't perform inlining in the front-end. For that, we'll need to
"fix" the `llvm.objectsize` intrinsic, but it's tougher than it looks.
https://github.com/llvm/llvm-project/pull/86858
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