On Mon, Jan 29, 2024 at 2:11 AM Jakub Jelinek <ja...@redhat.com> wrote:
>
> On Sat, Jan 27, 2024 at 07:00:03AM -0800, H.J. Lu wrote:
> > On Sat, Jan 27, 2024 at 6:09 AM Jakub Jelinek <ja...@redhat.com> wrote:
> > >
> > > On Sat, Jan 27, 2024 at 05:52:34AM -0800, H.J. Lu wrote:
> > > > @@ -3391,7 +3392,9 @@ ix86_set_func_type (tree fndecl)
> > > > function is marked as noreturn in the IR output, which leads the
> > > > incompatible attribute error in LTO1. */
> > > > bool has_no_callee_saved_registers
> > > > - = (((TREE_NOTHROW (fndecl) || !flag_exceptions)
> > > > + = ((optimize
> > > > + && !optimize_debug
> > >
> > > Shouldn't that be opt_for_fn (fndecl, optimize) and ditto for
> > > optimize_debug?
> > > I mean, aren't the options not restored yet when this function is called
> > > (i.e. remain in whatever state they were in the previous function or
> > > global state)?
> >
> > store_parm_decls is called when parsing a function. store_parm_decls
> > calls allocate_struct_function which calls
> >
> > invoke_set_current_function_hook (fndecl);
> >
> > which has
> >
> > /* Change optimization options if needed. */
> > if (optimization_current_node != opts)
> > {
> > optimization_current_node = opts;
> > cl_optimization_restore (&global_options, &global_options_set,
> > TREE_OPTIMIZATION (opts));
> > }
> >
> > targetm.set_current_function (fndecl);
> >
> > which calls ix86_set_current_function after global_options
> > has been updated. ix86_set_func_type is called from
> > ix86_set_current_function.
>
> Sorry, you're right, I just saw option restore later in
> ix86_set_current_function
> and missed that it is target option restore only.
>
> > > Also, why check "noreturn" attribute rather than
> > > TREE_THIS_VOLATILE (fndecl)?
> > >
> >
> > The comments above this code has
> >
> > NB: Don't use TREE_THIS_VOLATILE to check if this is a noreturn
> > function. The local-pure-const pass turns an interrupt function
> > into a noreturn function by setting TREE_THIS_VOLATILE. Normally
> > the local-pure-const pass is run after ix86_set_func_type is called.
> > When the local-pure-const pass is enabled for LTO, the interrupt
> > function is marked as noreturn in the IR output, which leads the
> > incompatible attribute error in LTO1.
>
> So in that case, I think it would be best to test
> TREE_THIS_VOLATILE (fndecl)
> && lookup_attribute ("noreturn", DECL_ATTRIBUTES (fndecl))
> && ...
> because if it doesn't have noreturn attribute, it will not have
> TREE_THIS_VOLATILE set and TREE_THIS_VOLATILE is much cheaper to test than
> looking an attribute.
>
Fixed in the v3 patch:
https://patchwork.sourceware.org/project/gcc/list/?series=30308
Thanks.
--
H.J.
