================
@@ -4073,6 +4221,51 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const
ArraySubscriptExpr *E,
ArrayLV = EmitLValue(Array);
auto *Idx = EmitIdxAfterBase(/*Promote*/true);
+ if (SanOpts.has(SanitizerKind::ArrayBounds)) {
+ // If the array being accessed has a "counted_by" attribute, generate
+ // bounds checking code. The "count" field is at the top level of the
+ // struct or in an anonymous struct, that's also at the top level. Future
+ // expansions may allow the "count" to reside at any place in the struct,
+ // but the value of "counted_by" will be a "simple" path to the count,
+ // i.e. "a.b.count", so we shouldn't need the full force of EmitLValue or
+ // similar to emit the correct GEP.
+ const LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel =
+ getLangOpts().getStrictFlexArraysLevel();
+
+ if (const auto *ME = dyn_cast<MemberExpr>(Array);
+ ME &&
+ ME->isFlexibleArrayMemberLike(getContext(), StrictFlexArraysLevel) &&
+ ME->getMemberDecl()->hasAttr<CountedByAttr>()) {
+ RecordDecl *RD = ME->getMemberDecl()
+ ->getDeclContext()
+ ->getOuterLexicalRecordContext();
----------------
rjmccall wrote:
Hmm. Is the use of `getOuterLexicalRecordContext()` just trying to look
through anonymous records? It makes sense that `counted_by` paths for members
of anonymous records would be specified starting from the containing
non-anonymous type, so we need to find that type. But I think
`getOuterLexicalRecordContext()` does too much here: it's actively wrong
whenever you have a record defined lexically within some other record, which
doesn't always look like the anonymous record pattern.
I think `getNonTransparentContext()` would be right, but you should also be
able to get the base type of the `counted_by` path from the attribute itself.
https://github.com/llvm/llvm-project/pull/73730
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