Re: [PATCH] Remove also 2nd argument for unused delete operator (PR tree-optimization/91270).

[Richard Biener <richard.guenther@gmail.com>]

On Tue, Jul 30, 2019 at 12:11 PM Martin Liška <mliska@suse.cz> wrote:
>
> On 7/30/19 10:40 AM, Richard Biener wrote:
> > On Tue, Jul 30, 2019 at 10:07 AM Martin Liška <mliska@suse.cz> wrote:
> >>
> >> On 7/30/19 9:46 AM, Martin Liška wrote:
> >>> Anyway that's not a candidate for DCE. I'm testing following patch.
> >>
> >> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> >>
> >> One alternative approach can be to drop DECL_SET_IS_OPERATOR_DELETE in:
> >> cat -n gcc/cp/decl.c | less
> >> ...
> >>   4410          deltype = cp_build_type_attribute_variant (deltype, extvisattr);
> >>   4411          deltype = build_exception_variant (deltype, empty_except_spec);
> >>   4412          opdel = push_cp_library_fn (DELETE_EXPR, deltype, ECF_NOTHROW);
> >>   4413          DECL_SET_IS_OPERATOR_DELETE (opdel, true);
> >>   4414          opdel = push_cp_library_fn (VEC_DELETE_EXPR, deltype, ECF_NOTHROW);
> >>   4415          DECL_SET_IS_OPERATOR_DELETE (opdel, true);
> >>   4416
> >>   4417          if (flag_sized_deallocation)
> >>   4418            {
> >>   4419              /* operator delete (void *, size_t, align_val_t); */
> >>   4420              deltype = build_function_type_list (void_type_node, ptr_type_node,
> >>   4421                                                  size_type_node, align_type_node,
> >>   4422                                                  NULL_TREE);
> >>   4423              deltype = cp_build_type_attribute_variant (deltype, extvisattr);
> >>   4424              deltype = build_exception_variant (deltype, empty_except_spec);
> >>   4425              opdel = push_cp_library_fn (DELETE_EXPR, deltype, ECF_NOTHROW);
> >>   4426              DECL_SET_IS_OPERATOR_DELETE (opdel, true);
> >>   4427              opdel = push_cp_library_fn (VEC_DELETE_EXPR, deltype, ECF_NOTHROW);
> >>   4428              DECL_SET_IS_OPERATOR_DELETE (opdel, true);
> >>   4429            }
> >>   4430        }
> >>
> >> at lines 4426 and 4428.
> >>
> >> Richi what do you prefer?
> >
> > I don't understand why a "not simple" delete operator isn't fine to be
> > DCEd?  Does C++
> > somehow allow mismatching size specifications here?
>
> No, they are the same.
>
> >  And what's the semantics
> > then?
> >
> > Thus I'd rather go with your earlier patch to mark the op necessary.
>
> Ok, I'm sending tested patch.
>
> Ready for trunk?

OK with the tests in

          if (gimple_call_builtin_p (stmt, BUILT_IN_FREE)
-             || (is_gimple_call (stmt)
-                 && gimple_call_operator_delete_p (as_a <gcall *> (stmt))))
-
+             || is_delete_operator)

exchanged (you already compuited is_delete_operator, no need to check for
BUILT_IN_FREE if it is true).

Richard.

> Thanks,
> Martin
>
> >
> > Richard.
> >
> >> Martin
>