On Mon, Apr 28, 2025 at 12:37 AM Jakub Jelinek <ja...@redhat.com> wrote:
>
> On Fri, Apr 25, 2025 at 09:12:45PM -0700, Andrew Pinski wrote:
> > --- a/gcc/tree-tailcall.cc
> > +++ b/gcc/tree-tailcall.cc
> > @@ -1083,57 +1083,74 @@ find_tail_calls (basic_block bb, struct tailcall
> > **ret, bool only_musttail,
> > {
> > bool ok = false;
> > value_range val;
> > - tree valr;
> > - /* If IPA-VRP proves called function always returns a singleton
> > range,
> > - the return value is replaced by the only value in that range.
> > - For tail call purposes, pretend such replacement didn't happen. */
> > if (ass_var == NULL_TREE && !tail_recursion)
> > - if (tree type = gimple_range_type (call))
> > - if (tree callee = gimple_call_fndecl (call))
> > - if ((INTEGRAL_TYPE_P (type)
> > - || SCALAR_FLOAT_TYPE_P (type)
> > - || POINTER_TYPE_P (type))
> > - && useless_type_conversion_p (TREE_TYPE (TREE_TYPE (callee)),
> > - type)
> > - && useless_type_conversion_p (TREE_TYPE (ret_var), type)
> > - && ipa_return_value_range (val, callee)
> > - && val.singleton_p (&valr))
> > + {
> > + tree other_value = NULL_TREE;
> > + /* If we have a function call that we know the return value is the
> > same
> > + as the argument, try the argument too. */
> > + int flags = gimple_call_return_flags (call);
> > + if ((flags & ERF_RETURNS_ARG) != 0
> > + && (flags & ERF_RETURN_ARG_MASK) < gimple_call_num_args (call))
> > + {
> > + tree arg = gimple_call_arg (call, flags & ERF_RETURN_ARG_MASK);
> > + if (useless_type_conversion_p (TREE_TYPE (arg), TREE_TYPE
> > (ret_var)))
>
> This should have the arguments swapped, i.e.
> if (useless_type_conversion_p (TREE_TYPE (ret_var), TREE_TYPE
> (arg)))
> because we want to check if the type of arg is uselessly convertible to the
> ret_var type (i.e. the return type).
Oh yes, I forgot that useless_type_conversion_p was not symmetric.
Thanks for the fix.
>
> Otherwise LGTM.
Just to double check, was this an approval after the fix for the call
to useless_type_conversion_p?
Thanks,
Andrew
>
> Jakub
>
