On Tue, Aug 16, 2016 at 3:14 PM, marxin <mli...@suse.cz> wrote:
> gcc/ChangeLog:
>
> 2016-08-16 Martin Liska <mli...@suse.cz>
>
> * builtins.c (fold_builtin_memchr): Support following
> transformations:
> memchr (x, y, 0) -> NULL
> memchr ("known_string", 'n', 5) -> &"known_string" + 1
> memchr ("known_string", 'n', 1) -> NULL
Aww. Can I convince you to move this and related foldings to gimple-fold.c?
Richard.
> ---
> gcc/builtins.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/gcc/builtins.c b/gcc/builtins.c
> index 8f1c752..ac251f8 100644
> --- a/gcc/builtins.c
> +++ b/gcc/builtins.c
> @@ -7267,8 +7267,12 @@ fold_builtin_memchr (location_t loc, tree arg1, tree
> arg2, tree len, tree type)
> || !tree_fits_uhwi_p (len))
> return NULL_TREE;
>
> + /* If the LEN parameter is zero, return zero. */
> + if (integer_zerop (len))
> + return build_int_cst (TREE_TYPE (arg1), 0);
> +
> p1 = c_getstr (arg1);
> - if (p1 && compare_tree_int (len, strlen (p1) + 1) <= 0)
> + if (p1)
> {
> char c;
> const char *r;
> @@ -7281,9 +7285,17 @@ fold_builtin_memchr (location_t loc, tree arg1, tree
> arg2, tree len, tree type)
>
> if (r == NULL)
> return build_int_cst (TREE_TYPE (arg1), 0);
> -
> - tem = fold_build_pointer_plus_hwi_loc (loc, arg1, r - p1);
> - return fold_convert_loc (loc, type, tem);
> + else
the else seems superfluous and just adds to indentation.
> + {
> + size_t offset = r - p1;
> + if (compare_tree_int (len, offset) <= 0)
> + return build_int_cst (TREE_TYPE (arg1), 0);
> + else
> + {
> + tem = fold_build_pointer_plus_hwi_loc (loc, arg1, offset);
> + return fold_convert_loc (loc, type, tem);
> + }
> + }
> }
> return NULL_TREE;
> }
> --
> 2.9.2
>
>
