[clang] [Clang][counted_by] Honor counted_by in __bdos on direct struct access (PR #201161)

[Justin Stitt via cfe-commits]

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@@ -16276,13 +16276,44 @@ static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc,
   return true;
 }
 
+/// Determine whether @p E designates a flexible array member annotated with
+/// 'counted_by'. This mirrors the Expr-walking that CGBuiltin's
+/// StructFieldAccess / emitCountedByMemberSize do to decide whether to emit
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JustinStitt wrote:

as in, I'd expect `__bdos(&af.fam, 1)` and `__bdos(af.fam, 1)` to eventually arrive at the same size in the IR. is this the case?

https://github.com/llvm/llvm-project/pull/201161