On Thu, 25 Jan 2018, Jakub Jelinek wrote:
> Hi!
>
> builtin_memref ctor for a SSA_NAME with non-NULL SSA_NAME_VAR returns
> the underlying variable, rather than just the SSA_NAME.
> Later on the code checks if the bases are equal and then compares
> corresponding offsets.
>
> The fact that two different SSA_NAMEs have the same underlying variable
> says nothing at all whether they have the same value, as the testcase shows,
> either the SSA_NAMEs can be completely unrelated, or related, but with
> different offsets. The code already has code to handle POINTER_PLUS_EXPR
> with a constant offset, to look through that. Perhaps in the future there
> can be other cases we'd special case, but generally we should compare as
> bases the SSA_NAMEs, if they have the same or different base says nothing
> about them.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Richard.
> 2018-01-25 Jakub Jelinek <ja...@redhat.com>
>
> PR c/83989
> * gimple-ssa-warn-restrict.c (builtin_memref::builtin_memref): Don't
> use SSA_NAME_VAR as base for SSA_NAMEs with non-NULL SSA_NAME_VAR.
>
> * c-c++-common/Wrestrict-3.c: New test.
>
> --- gcc/gimple-ssa-warn-restrict.c.jj 2018-01-17 11:54:17.000000000 +0100
> +++ gcc/gimple-ssa-warn-restrict.c 2018-01-25 14:10:26.182498552 +0100
> @@ -373,9 +373,6 @@ builtin_memref::builtin_memref (tree exp
> offrange[1] += off;
> }
> }
> -
> - if (TREE_CODE (base) == SSA_NAME && SSA_NAME_VAR (base))
> - base = SSA_NAME_VAR (base);
> }
>
> if (size)
> --- gcc/testsuite/c-c++-common/Wrestrict-3.c.jj 2018-01-25
> 14:16:01.574563425 +0100
> +++ gcc/testsuite/c-c++-common/Wrestrict-3.c 2018-01-25 14:14:39.273547506
> +0100
> @@ -0,0 +1,48 @@
> +/* PR c/83989 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -Wrestrict" } */
> +
> +__attribute__((__malloc__)) extern void *my_malloc (__SIZE_TYPE__);
> +void baz (void *);
> +
> +#define SIZE 32
> +
> +void
> +foo (void)
> +{
> + void *recmem = __builtin_malloc (SIZE);
> + baz (recmem);
> + while (1)
> + {
> + void *oldrecmem = recmem;
> + recmem = __builtin_malloc (SIZE);
> + if (!recmem)
> + {
> + __builtin_free (oldrecmem);
> + return;
> + }
> + __builtin_memcpy (recmem, oldrecmem, SIZE); /* { dg-bogus
> "accessing" } */
> + baz (recmem);
> + __builtin_free (oldrecmem);
> + }
> +}
> +
> +void
> +bar (void)
> +{
> + void *recmem = my_malloc (SIZE);
> + baz (recmem);
> + while (1)
> + {
> + void *oldrecmem = recmem;
> + recmem = my_malloc (SIZE);
> + if (!recmem)
> + {
> + __builtin_free (oldrecmem);
> + return;
> + }
> + __builtin_memcpy (recmem, oldrecmem, SIZE); /* { dg-bogus
> "accessing" } */
> + baz (recmem);
> + __builtin_free (oldrecmem);
> + }
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
