[PATCH] tree-optimization/108449 - keep maybe_special_function_p behavior

[PATCH] tree-optimization/108449 - keep maybe_special_function_p behavior

[Richard Biener]

When we have a static declaration without definition we diagnose
that and turn it into an extern declaration.  That can alter
the outcome of maybe_special_function_p here and there's really
no point in doing that, so don't.

Bootstrapped and tested on x86_64-unknown-linux-gnu, OK?

Thanks,
Richard.

	PR tree-optimization/108449
	* cgraphunit.cc (check_global_declaration): Do not turn
	undefined statics into externs.

	* gcc.dg/pr108449.c: New testcase.
---
 gcc/cgraphunit.cc               | 2 --
 gcc/testsuite/gcc.dg/pr108449.c | 5 +++++
 2 files changed, 5 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr108449.c

diff --git a/gcc/cgraphunit.cc b/gcc/cgraphunit.cc
index 59ce2708b7b..832818d651f 100644
--- a/gcc/cgraphunit.cc
+++ b/gcc/cgraphunit.cc
@@ -1087,8 +1087,6 @@ check_global_declaration (symtab_node *snode)
       else
 	warning (OPT_Wunused_function, "%q+F declared %<static%> but never "
 				       "defined", decl);
-      /* This symbol is effectively an "extern" declaration now.  */
-      TREE_PUBLIC (decl) = 1;
     }
 
   /* Warn about static fns or vars defined but not used.  */
diff --git a/gcc/testsuite/gcc.dg/pr108449.c b/gcc/testsuite/gcc.dg/pr108449.c
new file mode 100644
index 00000000000..4a3ae5b3ed4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr108449.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+static int vfork(); /* { dg-warning "used but never defined" } */
+void f() { vfork(); }
-- 
2.35.3

Re: [PATCH] tree-optimization/108449 - keep maybe_special_function_p behavior

[Jan Hubicka]

> When we have a static declaration without definition we diagnose
> that and turn it into an extern declaration.  That can alter
> the outcome of maybe_special_function_p here and there's really
> no point in doing that, so don't.
> 
> Bootstrapped and tested on x86_64-unknown-linux-gnu, OK?
> 
> Thanks,
> Richard.
> 
> 	PR tree-optimization/108449
> 	* cgraphunit.cc (check_global_declaration): Do not turn
> 	undefined statics into externs.
Looks OK to me. I got kind of suprrised we still have
maybe_special_function_p and we do chane of public flag.
I wonder if we can run into similar problem when promoting declaration
at LTO time?

Honza
> 
> 	* gcc.dg/pr108449.c: New testcase.
> ---
>  gcc/cgraphunit.cc               | 2 --
>  gcc/testsuite/gcc.dg/pr108449.c | 5 +++++
>  2 files changed, 5 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.dg/pr108449.c
> 
> diff --git a/gcc/cgraphunit.cc b/gcc/cgraphunit.cc
> index 59ce2708b7b..832818d651f 100644
> --- a/gcc/cgraphunit.cc
> +++ b/gcc/cgraphunit.cc
> @@ -1087,8 +1087,6 @@ check_global_declaration (symtab_node *snode)
>        else
>  	warning (OPT_Wunused_function, "%q+F declared %<static%> but never "
>  				       "defined", decl);
> -      /* This symbol is effectively an "extern" declaration now.  */
> -      TREE_PUBLIC (decl) = 1;
>      }
>  
>    /* Warn about static fns or vars defined but not used.  */
> diff --git a/gcc/testsuite/gcc.dg/pr108449.c b/gcc/testsuite/gcc.dg/pr108449.c
> new file mode 100644
> index 00000000000..4a3ae5b3ed4
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr108449.c
> @@ -0,0 +1,5 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O" } */
> +
> +static int vfork(); /* { dg-warning "used but never defined" } */
> +void f() { vfork(); }
> -- 
> 2.35.3

Re: [PATCH] tree-optimization/108449 - keep maybe_special_function_p behavior

[Richard Biener]

On Sat, 21 Jan 2023, Jan Hubicka wrote:

> > When we have a static declaration without definition we diagnose
> > that and turn it into an extern declaration.  That can alter
> > the outcome of maybe_special_function_p here and there's really
> > no point in doing that, so don't.
> > 
> > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK?
> > 
> > Thanks,
> > Richard.
> > 
> > 	PR tree-optimization/108449
> > 	* cgraphunit.cc (check_global_declaration): Do not turn
> > 	undefined statics into externs.
> Looks OK to me. I got kind of suprrised we still have
> maybe_special_function_p and we do chane of public flag.

Yeah, well ...

> I wonder if we can run into similar problem when promoting declaration
> at LTO time?

Possibly - I guess we could amend maybe_special_function_p to check
if there's a visible definition.  Or somehow get rid of this thing
and apply the special-function 'name' thing as explicit attributes
during parsing instead ...

Richard.

> Honza
> > 
> > 	* gcc.dg/pr108449.c: New testcase.
> > ---
> >  gcc/cgraphunit.cc               | 2 --
> >  gcc/testsuite/gcc.dg/pr108449.c | 5 +++++
> >  2 files changed, 5 insertions(+), 2 deletions(-)
> >  create mode 100644 gcc/testsuite/gcc.dg/pr108449.c
> > 
> > diff --git a/gcc/cgraphunit.cc b/gcc/cgraphunit.cc
> > index 59ce2708b7b..832818d651f 100644
> > --- a/gcc/cgraphunit.cc
> > +++ b/gcc/cgraphunit.cc
> > @@ -1087,8 +1087,6 @@ check_global_declaration (symtab_node *snode)
> >        else
> >  	warning (OPT_Wunused_function, "%q+F declared %<static%> but never "
> >  				       "defined", decl);
> > -      /* This symbol is effectively an "extern" declaration now.  */
> > -      TREE_PUBLIC (decl) = 1;
> >      }
> >  
> >    /* Warn about static fns or vars defined but not used.  */
> > diff --git a/gcc/testsuite/gcc.dg/pr108449.c b/gcc/testsuite/gcc.dg/pr108449.c
> > new file mode 100644
> > index 00000000000..4a3ae5b3ed4
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/pr108449.c
> > @@ -0,0 +1,5 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O" } */
> > +
> > +static int vfork(); /* { dg-warning "used but never defined" } */
> > +void f() { vfork(); }
> > -- 
> > 2.35.3
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)