[PATCH] handle bzero/bcopy in DSE and aliasing (PR 80933, 80934)

[Martin Sebor]

> +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.
>
> Ok with that changes.

I made these changes along with those mentioned downthread and
committed r249278.

Martin