On Fri, Dec 08, 2017 at 03:44:03PM +0100, Richard Biener wrote:
>
> The following fixes spurious uninit warnings for zero-sized arrays.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
>
> Richard.
>
> 2017-12-08 Richard Biener <rguent...@suse.de>
>
> PR middle-end/81782
> * tree-ssa-uninit.c (warn_uninitialized_vars): Properly
> handle accesses outside of zero-sized vars.
Is ref.max_size == -1 always guaranteeing no access before offset, only
after it?
What I fear is e.g. ARRAY_REF with non-constant index with base of
MEM_REF with & of a middle of array or something similar?
struct S { int x[64]; } foo;
MEM_REF[&foo, 40][i] with negative i.
Anyway, in this case it is about not printing a warning, so we can give up
even if it is theoretically possible.
> --- gcc/tree-ssa-uninit.c (revision 255499)
> +++ gcc/tree-ssa-uninit.c (working copy)
> @@ -296,8 +296,8 @@ warn_uninitialized_vars (bool warn_possi
> variable. */
> if (DECL_P (base)
> && ref.size != -1
> - && ref.max_size == ref.size
> - && (ref.offset + ref.size <= 0
> + && ((ref.max_size == ref.size
> + && ref.offset + ref.size <= 0)
> || (ref.offset >= 0
> && DECL_SIZE (base)
> && TREE_CODE (DECL_SIZE (base)) == INTEGER_CST
Jakub
