On Fri, Jun 09, 2017 at 02:35:45PM +0200, Richard Biener wrote:
> +static bool
> +gimple_fold_builtin_bcmp (gimple_stmt_iterator *gsi)
> +{
>
> + /* Transform bcmp (a, b, len) into memcmp (a, b, len). */
> +
> + gimple *stmt = gsi_stmt (*gsi);
> + tree a = gimple_call_arg (stmt, 0);
> + tree b = gimple_call_arg (stmt, 1);
> + tree len = gimple_call_arg (stmt, 2);
> +
> + gimple_seq seq = NULL;
> + gimple *repl = gimple_build_call (fn, 3, a, b, len);
> + gimple_seq_add_stmt_without_update (&seq, repl);
> + gsi_replace_with_seq_vops (gsi, seq);
>
> given they have the same prototype you can do like gimple_fold_builtin_stpcpy:
>
> gimple_call_set_fndecl (stmt, fn);
> fold_stmt (gsi);
>
> That works even with bcopy -> memmove if you swap arguments.
Shouldn't it also update gimple_call_fntype though, at least for memmove?
Those differ with void const * vs. void * arguments, and also in the return
value. At least if the old fntype is compatible with the bcopy call.
Jakub
