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.
Jakub
