On Thu, Jul 10, 2025 at 04:03:29PM +0000, Qing Zhao wrote:
> The size of the element of the FAM _cannot_ reliably depends on the original
> TYPE of the FAM that we passed as the 6th parameter to the .ACCESS_WITH_SIZE:
>
> TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (gimple_call_arg (call, 5))))
>
> when the element of the FAM has a variable length type. Since the variable
> that represents TYPE_SIZE_UNIT has no explicit usage in the original IL,
> compiler transformations (such as DSE) that are applied before object_size
> phase might eliminate the whole definition to the variable that represents
> the TYPE_SIZE_UNIT of the element of the FAM.
>
> In order to resolve this issue, instead of passing the original TYPE of the
> FAM as the 6th argument to .ACCESS_WITH_SIZE, we should explicitly pass the
> original TYPE_SIZE_UNIT of the element TYPE of the FAM as the 6th argument
> to the call to .ACCESS_WITH_SIZE.
>
> The patches have been bootstrapped and regression tested on both aarch64
> and x86.
>
> Okay for trunk?
>
> thanks.
>
> Qing
>
> PR middle-end/121000
>
> gcc/c/ChangeLog:
>
> * c-typeck.cc (build_counted_by_ref): Update comments.
You can't trust mklog that much. You're updating
build_access_with_size_for_counted_by function comment, not
build_counted_by_ref comments.
> (build_access_with_size_for_counted_by): Pass TYPE_SIZE_UNIT of the
> element as the 6th argument.
>
> gcc/ChangeLog:
>
> * internal-fn.cc (expand_DEFERRED_INIT): Update comments.
> * internal-fn.def (DEFERRED_INIT): Update comments.
Nor these two. It is expand_ACCESS_WITH_SIZE and ACCESS_WITH_SIZE
in these cases.
> * tree-object-size.cc (access_with_size_object_size): Update comments.
> Get the element_size from the 6th argument directly.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/flex-array-counted-by-pr121000.c: New test.
Otherwise LGTM with one nit.
> +int main ()
Line break before main.
Jakub
