On Thu, 25 Jan 2018, Jan Hubicka wrote:
> Hi,
> the testcase triggers invalid warning on type mismatch because array
> of pointers to complete type has different alias set from array of pointers
> to incomplete type. This is valid, because incoplete pointer has alias set
> of void_ptr which alias all pointers and arrays alias with their members.
But isn't that a problem? Not if the pointer to incomlete type have
alias set zero but IIRC they don't, right?
Richard.
> I already silenced the wanring for pointers but I forgot about arrays.
>
> Bootstrapped/regtested x86_64-linux, OK?
>
> * gcc.dg/lto/pr83954.h: New testcase.
> * gcc.dg/lto/pr83954_0.c: New testcase.
> * gcc.dg/lto/pr83954_1.c: New testcase.
> * lto-symtab.c (warn_type_compatibility_p): Silence false positive
> for type match warning on arrays of pointers.
>
> Index: testsuite/gcc.dg/lto/pr83954.h
> ===================================================================
> --- testsuite/gcc.dg/lto/pr83954.h (revision 0)
> +++ testsuite/gcc.dg/lto/pr83954.h (working copy)
> @@ -0,0 +1,3 @@
> +struct foo;
> +extern struct foo *FOO_PTR_ARR[1];
> +
> Index: testsuite/gcc.dg/lto/pr83954_0.c
> ===================================================================
> --- testsuite/gcc.dg/lto/pr83954_0.c (revision 0)
> +++ testsuite/gcc.dg/lto/pr83954_0.c (working copy)
> @@ -0,0 +1,8 @@
> +/* { dg-lto-do link } */
> +#include "pr83954.h"
> +
> +int main() {
> + // just to prevent symbol removal
> + FOO_PTR_ARR[1] = 0;
> + return 0;
> +}
> Index: testsuite/gcc.dg/lto/pr83954_1.c
> ===================================================================
> --- testsuite/gcc.dg/lto/pr83954_1.c (revision 0)
> +++ testsuite/gcc.dg/lto/pr83954_1.c (working copy)
> @@ -0,0 +1,7 @@
> +#include "pr83954.h"
> +
> +struct foo {
> + int x;
> +};
> +struct foo *FOO_PTR_ARR[1] = { 0 };
> +
> Index: lto/lto-symtab.c
> ===================================================================
> --- lto/lto-symtab.c (revision 257009)
> +++ lto/lto-symtab.c (working copy)
> @@ -284,11 +284,22 @@ warn_type_compatibility_p (tree prevaili
> alias_set_type set1 = get_alias_set (type);
> alias_set_type set2 = get_alias_set (prevailing_type);
>
> - if (set1 && set2 && set1 != set2
> - && (!POINTER_TYPE_P (type) || !POINTER_TYPE_P (prevailing_type)
> + if (set1 && set2 && set1 != set2)
> + {
> + tree t1 = type, t2 = prevailing_type;
> +
> + /* Alias sets of arrays are the same as alias sets of the inner
> + types. */
> + while (TREE_CODE (t1) == ARRAY_TYPE && TREE_CODE (t2) == ARRAY_TYPE)
> + {
> + t1 = TREE_TYPE (t1);
> + t2 = TREE_TYPE (t2);
> + }
> + if ((!POINTER_TYPE_P (t1) || !POINTER_TYPE_P (t2))
> || (set1 != TYPE_ALIAS_SET (ptr_type_node)
> - && set2 != TYPE_ALIAS_SET (ptr_type_node))))
> - lev |= 5;
> + && set2 != TYPE_ALIAS_SET (ptr_type_node)))
> + lev |= 5;
> + }
> }
>
> return lev;
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
