On Fri, Jan 14, 2022 at 09:01:09AM +0530, Siddhesh Poyarekar wrote:
> Restrict negative offset computation only to dynamic object sizes, where
> size expressions are accurate and not a maximum/minimum estimate and in
> cases where negative offsets definitely mean an underflow, e.g. in
> MEM_REF of the whole object with negative ofset in addr_object_size.
>
> This ends up missing some cases where __builtin_object_size could have
> come up with more precise results, so tests have been adjusted to
> reflect that.
>
> gcc/ChangeLog:
>
> PR tree-optimization/104009
> * tree-object-size.c (compute_builtin_object_size): Bail out on
> negative offset.
> (plus_stmt_object_size): Return maximum of wholesize and minimum
> of 0 for negative offset.
>
> gcc/testsuite/ChangeLog:
>
> PR tree-optimization/104009
> * gcc.dg/builtin-object-size-1.c (test10): New test.
> * gcc.dg/builtin-object-size-3.c (test10): Likewise.
> (test9): Expect zero size for negative offsets.
> * gcc.dg/builtin-object-size-4.c (test8): Likewise.
> * gcc.dg/builtin-object-size-5.c (test7): Drop test for
> __builtin_object_size.
Ok.
Jakub
