================
@@ -859,53 +859,60 @@ CodeGenFunction::emitBuiltinObjectSize(const Expr *E,
unsigned Type,
}
if (IsDynamic) {
- LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel =
- getLangOpts().getStrictFlexArraysLevel();
- const Expr *Base = E->IgnoreParenImpCasts();
-
- if (FieldDecl *FD = FindCountedByField(Base, StrictFlexArraysLevel)) {
- const auto *ME = dyn_cast<MemberExpr>(Base);
- llvm::Value *ObjectSize = nullptr;
-
- if (!ME) {
- const auto *DRE = dyn_cast<DeclRefExpr>(Base);
- ValueDecl *VD = nullptr;
-
- ObjectSize = ConstantInt::get(
- ResType,
- getContext().getTypeSize(DRE->getType()->getPointeeType()) / 8,
- true);
-
- if (auto *RD = DRE->getType()->getPointeeType()->getAsRecordDecl())
- VD = RD->getLastField();
-
- Expr *ICE = ImplicitCastExpr::Create(
- getContext(), DRE->getType(), CK_LValueToRValue,
- const_cast<Expr *>(cast<Expr>(DRE)), nullptr, VK_PRValue,
- FPOptionsOverride());
- ME = MemberExpr::CreateImplicit(getContext(), ICE, true, VD,
- VD->getType(), VK_LValue, OK_Ordinary);
- }
-
- // At this point, we know that \p ME is a flexible array member.
- const auto *ArrayTy = getContext().getAsArrayType(ME->getType());
+ // The code generated here calculates the size of a struct with a flexible
+ // array member that uses the counted_by attribute. There are two instances
+ // we handle:
+ //
+ // struct s {
+ // unsigned long flags;
+ // int count;
+ // int array[] __attribute__((counted_by(count)));
+ // }
+ //
+ // 1) bdos of the flexible array itself:
+ //
+ // __builtin_dynamic_object_size(p->array, 1) ==
+ // p->count * sizeof(*p->array)
+ //
+ // 2) bdos of the whole struct, including the flexible array:
+ //
+ // __builtin_dynamic_object_size(p, 1) ==
+ // sizeof(*p) + p->count * sizeof(*p->array)
+ //
+ if (const ValueDecl *CountedByFD = FindCountedByField(E)) {
+ // Find the flexible array member.
+ const RecordDecl *OuterRD =
+ CountedByFD->getDeclContext()->getOuterLexicalRecordContext();
+ const ValueDecl *FAM =
+ FindFlexibleArrayMemberField(getContext(), OuterRD);
+
+ // Find the outer struct expr (i.e. p in p->a.b.c.d).
+ Expr *CountedByExpr =
+ BuildCountedByFieldExpr(const_cast<Expr *>(E), CountedByFD);
----------------
bwendling wrote:
I agree that it's gross.
The `const_cast` s are needed, because `EmitAnyExprToTemp` requires it to be
non-const. It's gross, but unfortunately necessary. I put the cast here to keep
the `BuildCountedByFieldExpr` nicer with regard to const_casts. To be honest,
I'm not sure why the `Emit*Expr` methods use non-const `Expr` pointers. Seems
unnecessary to me... :-/
https://github.com/llvm/llvm-project/pull/70606
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
