pch, v2: Add support for PCH for relocatable executables

  On Mon, Nov 08, 2021 at 08:48:07PM +0100, Jakub Jelinek via Gcc-patches wrote:
> On Mon, Nov 08, 2021 at 12:46:04PM +0100, Jakub Jelinek via Gcc-patches wrote:
> > So, if we want to make PCH work for PIEs, I'd say we can:
> > 1) add a new GTY option, say callback, which would act like
> >    skip for non-PCH and for PCH would make us skip it but
> >    remember for address bias translation
> > 2) drop the skip for tree_translation_unit_decl::language
> > 3) change get_unnamed_section to have const char * as
> >    last argument instead of const void *, change
> >    unnamed_section::data also to const char * and update
> >    everything related to that
> > 4) maybe add a host hook whether it is ok to support binaries
> >    changing addresses (the only thing I'm worried is if
> >    some host that uses function descriptors allocates them
> >    dynamically instead of having them somewhere in the
> >    executable)
> > 5) maybe add a gengtype warning if it sees in GTY tracked
> >    structure a function pointer without that new callback
> >    option
> 
> So, here is 1), 2), 3) implemented.  With this patch alone,
> g++.dg/pch/system-2.C test ICEs.  This is because GCC 12 has added
> function::x_range_query member, which is set to &global_ranges on
> cfun creation and is:
>   range_query * GTY ((skip)) x_range_query;
> which means when a PIE binary writes PCH and a PIE binary loaded
> at a different address loads it, cfun->x_range_query might be a garbage
> pointer.  We can either apply a patch like the attached one after
> this inline patch, but then probably callback is misnamed and we should
> rename it to relocate_and_skip or something similar.  Or we could
> e.g. during gimplification overwrite cfun->x_range_query = &global_ranges.
> Other than that make check-gcc check-g++ passes RUNTESTFLAGS=pch.exp.
> 
> Note, on stdc++.h.gch/O2g.gch there are just those 10 relocations without
> the second patch, with it a few more, but nothing huge.  And for non-PIEs
> there isn't really any extra work on the load side except freading two scalar
> values and fseek.

Here is an updated version (the previous version doesn't apply any longer
in gt_pch_restore due to the line_maps saving/restoring changes).

Bootstrapped/regtested on x86_64-linux and i686-linux with
--enable-host-shared in addition to normal configure options (and without
Ada which doesn't even with the above options build PIC libgnat.a and links
it) and a hack:


	Jakub
  

On 11/18/2021 1:04 AM, Jakub Jelinek wrote:
> On Mon, Nov 08, 2021 at 08:48:07PM +0100, Jakub Jelinek via Gcc-patches wrote:
>> On Mon, Nov 08, 2021 at 12:46:04PM +0100, Jakub Jelinek via Gcc-patches wrote:
>>> So, if we want to make PCH work for PIEs, I'd say we can:
>>> 1) add a new GTY option, say callback, which would act like
>>>     skip for non-PCH and for PCH would make us skip it but
>>>     remember for address bias translation
>>> 2) drop the skip for tree_translation_unit_decl::language
>>> 3) change get_unnamed_section to have const char * as
>>>     last argument instead of const void *, change
>>>     unnamed_section::data also to const char * and update
>>>     everything related to that
>>> 4) maybe add a host hook whether it is ok to support binaries
>>>     changing addresses (the only thing I'm worried is if
>>>     some host that uses function descriptors allocates them
>>>     dynamically instead of having them somewhere in the
>>>     executable)
>>> 5) maybe add a gengtype warning if it sees in GTY tracked
>>>     structure a function pointer without that new callback
>>>     option
>> So, here is 1), 2), 3) implemented.  With this patch alone,
>> g++.dg/pch/system-2.C test ICEs.  This is because GCC 12 has added
>> function::x_range_query member, which is set to &global_ranges on
>> cfun creation and is:
>>    range_query * GTY ((skip)) x_range_query;
>> which means when a PIE binary writes PCH and a PIE binary loaded
>> at a different address loads it, cfun->x_range_query might be a garbage
>> pointer.  We can either apply a patch like the attached one after
>> this inline patch, but then probably callback is misnamed and we should
>> rename it to relocate_and_skip or something similar.  Or we could
>> e.g. during gimplification overwrite cfun->x_range_query = &global_ranges.
>> Other than that make check-gcc check-g++ passes RUNTESTFLAGS=pch.exp.
>>
>> Note, on stdc++.h.gch/O2g.gch there are just those 10 relocations without
>> the second patch, with it a few more, but nothing huge.  And for non-PIEs
>> there isn't really any extra work on the load side except freading two scalar
>> values and fseek.
> Here is an updated version (the previous version doesn't apply any longer
> in gt_pch_restore due to the line_maps saving/restoring changes).
>
> Bootstrapped/regtested on x86_64-linux and i686-linux with
> --enable-host-shared in addition to normal configure options (and without
> Ada which doesn't even with the above options build PIC libgnat.a and links
> it) and a hack:
> --- gcc/configure.ac.jj	2021-10-28 22:12:31.569299780 +0200
> +++ gcc/configure.ac	2021-11-09 11:34:33.453776105 +0100
> @@ -7566,7 +7566,7 @@ AC_CACHE_CHECK([for -no-pie option],
>        [gcc_cv_no_pie=no])
>      LDFLAGS="$saved_LDFLAGS"])
>   if test "$gcc_cv_no_pie" = "yes"; then
> -  NO_PIE_FLAG="-no-pie"
> +  NO_PIE_FLAG="-pie"
>   fi
>   AC_SUBST([NO_PIE_FLAG])
>   
> to force binaries be PIE, no regressions against non-PIC/PIE build
> without this patch.  Ok for trunk?
>
> 2021-11-18  Jakub Jelinek  <jakub@redhat.com>
>
> 	PR pch/71934
> gcc/
> 	* ggc.h (gt_pch_note_callback): Declare.
> 	* gengtype.h (enum typekind): Add TYPE_CALLBACK.
> 	(callback_type): Declare.
> 	* gengtype.c (dbgprint_count_type_at): Handle TYPE_CALLBACK.
> 	(callback_type): New variable.
> 	(process_gc_options): Add CALLBACK argument, handle callback
> 	option.
> 	(set_gc_used_type): Adjust process_gc_options caller, if callback,
> 	set type to &callback_type.
> 	(output_mangled_typename): Handle TYPE_CALLBACK.
> 	(walk_type): Likewise.  Handle callback option.
> 	(write_types_process_field): Handle TYPE_CALLBACK.
> 	(write_types_local_user_process_field): Likewise.
> 	(write_types_local_process_field): Likewise.
> 	(write_root): Likewise.
> 	(dump_typekind): Likewise.
> 	(dump_type): Likewise.
> 	* gengtype-state.c (type_lineloc): Handle TYPE_CALLBACK.
> 	(state_writer::write_state_callback_type): New method.
> 	(state_writer::write_state_type): Handle TYPE_CALLBACK.
> 	(read_state_callback_type): New function.
> 	(read_state_type): Handle TYPE_CALLBACK.
> 	* ggc-common.c (callback_vec): New variable.
> 	(gt_pch_note_callback): New function.
> 	(gt_pch_save): Stream out gt_pch_save function address and relocation
> 	table.
> 	(gt_pch_restore): Stream in saved gt_pch_save function address and
> 	relocation table and apply relocations if needed.
> 	* doc/gty.texi (callback): Document new GTY option.
> 	* varasm.c (get_unnamed_section): Change callback argument's type and
> 	last argument's type from const void * to const char *.
> 	(output_section_asm_op): Change argument's type from const void *
> 	to const char *, remove unnecessary cast.
> 	* tree-core.h (struct tree_translation_unit_decl): Drop GTY((skip))
> 	from language member.
> 	* output.h (unnamed_section_callback): Change argument type from
> 	const void * to const char *.
> 	(struct unnamed_section): Use GTY((callback)) instead of GTY((skip))
> 	for callback member.  Change data member type from const void *
> 	to const char *.
> 	(struct noswitch_section): Use GTY((callback)) instead of GTY((skip))
> 	for callback member.
> 	(get_unnamed_section): Change callback argument's type and
> 	last argument's type from const void * to const char *.
> 	(output_section_asm_op): Change argument's type from const void *
> 	to const char *.
> 	* config/avr/avr.c (avr_output_progmem_section_asm_op): Likewise.
> 	Remove unneeded cast.
> 	* config/darwin.c (output_objc_section_asm_op): Change argument's type
> 	from const void * to const char *.
> 	* config/pa/pa.c (som_output_text_section_asm_op): Likewise.
> 	(som_output_comdat_data_section_asm_op): Likewise.
> 	* config/rs6000/rs6000.c (rs6000_elf_output_toc_section_asm_op):
> 	Likewise.
> 	(rs6000_xcoff_output_readonly_section_asm_op): Likewise.  Instead
> 	of dereferencing directive hardcode variable names and decide based on
> 	whether directive is NULL or not.
> 	(rs6000_xcoff_output_readwrite_section_asm_op): Change argument's type
> 	from const void * to const char *.
> 	(rs6000_xcoff_output_tls_section_asm_op): Likewise.  Instead
> 	of dereferencing directive hardcode variable names and decide based on
> 	whether directive is NULL or not.
> 	(rs6000_xcoff_output_toc_section_asm_op): Change argument's type
> 	from const void * to const char *.
> 	(rs6000_xcoff_asm_init_sections): Adjust get_unnamed_section callers.
> gcc/c-family/
> 	* c-pch.c (struct c_pch_validity): Remove pch_init member.
> 	(pch_init): Don't initialize v.pch_init.
> 	(c_common_valid_pch): Don't warn and punt if .text addresses change.
> libcpp/
> 	* include/line-map.h (class line_maps): Add GTY((callback)) to
> 	reallocator and round_alloc_size members.
You know this code better than anyone I suspect.  If it's working and 
you're confortable with it, I suggest going forward with it.

Jeff
  

On 11/18/21 09:04, Jakub Jelinek via Gcc-patches wrote:
> On Mon, Nov 08, 2021 at 08:48:07PM +0100, Jakub Jelinek via Gcc-patches wrote:
>> On Mon, Nov 08, 2021 at 12:46:04PM +0100, Jakub Jelinek via Gcc-patches wrote:
>>> So, if we want to make PCH work for PIEs, I'd say we can:
>>> 1) add a new GTY option, say callback, which would act like
>>>     skip for non-PCH and for PCH would make us skip it but
>>>     remember for address bias translation
>>> 2) drop the skip for tree_translation_unit_decl::language
>>> 3) change get_unnamed_section to have const char * as
>>>     last argument instead of const void *, change
>>>     unnamed_section::data also to const char * and update
>>>     everything related to that
>>> 4) maybe add a host hook whether it is ok to support binaries
>>>     changing addresses (the only thing I'm worried is if
>>>     some host that uses function descriptors allocates them
>>>     dynamically instead of having them somewhere in the
>>>     executable)
>>> 5) maybe add a gengtype warning if it sees in GTY tracked
>>>     structure a function pointer without that new callback
>>>     option
>>
>> So, here is 1), 2), 3) implemented.  With this patch alone,
>> g++.dg/pch/system-2.C test ICEs.  This is because GCC 12 has added
>> function::x_range_query member, which is set to &global_ranges on
>> cfun creation and is:
>>    range_query * GTY ((skip)) x_range_query;
>> which means when a PIE binary writes PCH and a PIE binary loaded
>> at a different address loads it, cfun->x_range_query might be a garbage
>> pointer.  We can either apply a patch like the attached one after
>> this inline patch, but then probably callback is misnamed and we should
>> rename it to relocate_and_skip or something similar.  Or we could
>> e.g. during gimplification overwrite cfun->x_range_query = &global_ranges.
>> Other than that make check-gcc check-g++ passes RUNTESTFLAGS=pch.exp.
>>
>> Note, on stdc++.h.gch/O2g.gch there are just those 10 relocations without
>> the second patch, with it a few more, but nothing huge.  And for non-PIEs
>> there isn't really any extra work on the load side except freading two scalar
>> values and fseek.
> 
> Here is an updated version (the previous version doesn't apply any longer
> in gt_pch_restore due to the line_maps saving/restoring changes).
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux with
> --enable-host-shared in addition to normal configure options (and without
> Ada which doesn't even with the above options build PIC libgnat.a and links
> it) and a hack:
> --- gcc/configure.ac.jj	2021-10-28 22:12:31.569299780 +0200
> +++ gcc/configure.ac	2021-11-09 11:34:33.453776105 +0100
> @@ -7566,7 +7566,7 @@ AC_CACHE_CHECK([for -no-pie option],
>        [gcc_cv_no_pie=no])
>      LDFLAGS="$saved_LDFLAGS"])
>   if test "$gcc_cv_no_pie" = "yes"; then
> -  NO_PIE_FLAG="-no-pie"
> +  NO_PIE_FLAG="-pie"
>   fi
>   AC_SUBST([NO_PIE_FLAG])
>   
> to force binaries be PIE, no regressions against non-PIC/PIE build
> without this patch.  Ok for trunk?
> 
> 2021-11-18  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR pch/71934
> gcc/
> 	* ggc.h (gt_pch_note_callback): Declare.
> 	* gengtype.h (enum typekind): Add TYPE_CALLBACK.
> 	(callback_type): Declare.
> 	* gengtype.c (dbgprint_count_type_at): Handle TYPE_CALLBACK.
> 	(callback_type): New variable.
> 	(process_gc_options): Add CALLBACK argument, handle callback
> 	option.
> 	(set_gc_used_type): Adjust process_gc_options caller, if callback,
> 	set type to &callback_type.
> 	(output_mangled_typename): Handle TYPE_CALLBACK.
> 	(walk_type): Likewise.  Handle callback option.
> 	(write_types_process_field): Handle TYPE_CALLBACK.
> 	(write_types_local_user_process_field): Likewise.
> 	(write_types_local_process_field): Likewise.
> 	(write_root): Likewise.
> 	(dump_typekind): Likewise.
> 	(dump_type): Likewise.
> 	* gengtype-state.c (type_lineloc): Handle TYPE_CALLBACK.
> 	(state_writer::write_state_callback_type): New method.
> 	(state_writer::write_state_type): Handle TYPE_CALLBACK.
> 	(read_state_callback_type): New function.
> 	(read_state_type): Handle TYPE_CALLBACK.
> 	* ggc-common.c (callback_vec): New variable.
> 	(gt_pch_note_callback): New function.
> 	(gt_pch_save): Stream out gt_pch_save function address and relocation
> 	table.
> 	(gt_pch_restore): Stream in saved gt_pch_save function address and
> 	relocation table and apply relocations if needed.
> 	* doc/gty.texi (callback): Document new GTY option.
> 	* varasm.c (get_unnamed_section): Change callback argument's type and
> 	last argument's type from const void * to const char *.
> 	(output_section_asm_op): Change argument's type from const void *
> 	to const char *, remove unnecessary cast.
> 	* tree-core.h (struct tree_translation_unit_decl): Drop GTY((skip))
> 	from language member.
> 	* output.h (unnamed_section_callback): Change argument type from
> 	const void * to const char *.
> 	(struct unnamed_section): Use GTY((callback)) instead of GTY((skip))
> 	for callback member.  Change data member type from const void *
> 	to const char *.
> 	(struct noswitch_section): Use GTY((callback)) instead of GTY((skip))
> 	for callback member.
> 	(get_unnamed_section): Change callback argument's type and
> 	last argument's type from const void * to const char *.
> 	(output_section_asm_op): Change argument's type from const void *
> 	to const char *.
> 	* config/avr/avr.c (avr_output_progmem_section_asm_op): Likewise.
> 	Remove unneeded cast.
> 	* config/darwin.c (output_objc_section_asm_op): Change argument's type
> 	from const void * to const char *.
> 	* config/pa/pa.c (som_output_text_section_asm_op): Likewise.
> 	(som_output_comdat_data_section_asm_op): Likewise.
> 	* config/rs6000/rs6000.c (rs6000_elf_output_toc_section_asm_op):
> 	Likewise.
> 	(rs6000_xcoff_output_readonly_section_asm_op): Likewise.  Instead
> 	of dereferencing directive hardcode variable names and decide based on
> 	whether directive is NULL or not.
> 	(rs6000_xcoff_output_readwrite_section_asm_op): Change argument's type
> 	from const void * to const char *.
> 	(rs6000_xcoff_output_tls_section_asm_op): Likewise.  Instead
> 	of dereferencing directive hardcode variable names and decide based on
> 	whether directive is NULL or not.
> 	(rs6000_xcoff_output_toc_section_asm_op): Change argument's type
> 	from const void * to const char *.
> 	(rs6000_xcoff_asm_init_sections): Adjust get_unnamed_section callers.
> gcc/c-family/
> 	* c-pch.c (struct c_pch_validity): Remove pch_init member.
> 	(pch_init): Don't initialize v.pch_init.
> 	(c_common_valid_pch): Don't warn and punt if .text addresses change.
> libcpp/
> 	* include/line-map.h (class line_maps): Add GTY((callback)) to
> 	reallocator and round_alloc_size members.
> 
> --- gcc/ggc.h.jj	2021-08-19 11:42:27.366422386 +0200
> +++ gcc/ggc.h	2021-11-08 16:46:02.604618109 +0100
> @@ -46,6 +46,10 @@ typedef void (*gt_handle_reorder) (void
>   /* Used by the gt_pch_n_* routines.  Register an object in the hash table.  */
>   extern int gt_pch_note_object (void *, void *, gt_note_pointers);
>   
> +/* Used by the gt_pch_p_* routines.  Register address of a callback
> +   pointer.  */
> +extern void gt_pch_note_callback (void *, void *);
> +
>   /* Used by the gt_pch_n_* routines.  Register that an object has a reorder
>      function.  */
>   extern void gt_pch_note_reorder (void *, void *, gt_handle_reorder);
> --- gcc/gengtype.h.jj	2021-07-20 10:08:09.892687719 +0200
> +++ gcc/gengtype.h	2021-11-08 15:19:59.194210185 +0100
> @@ -154,6 +154,9 @@ enum typekind {
>     TYPE_UNION,           /* Type for GTY-ed discriminated unions.  */
>     TYPE_POINTER,         /* Pointer type to GTY-ed type.  */
>     TYPE_ARRAY,           /* Array of GTY-ed types.  */
> +  TYPE_CALLBACK,	/* A function pointer that needs relocation if
> +			   the executable has been loaded at a different
> +			   address.  */
>     TYPE_LANG_STRUCT,     /* GCC front-end language specific structs.
>                              Various languages may have homonymous but
>                              different structs.  */
> @@ -331,6 +334,9 @@ extern struct type string_type;
>   extern struct type scalar_nonchar;
>   extern struct type scalar_char;
>   
> +/* The one and only TYPE_CALLBACK.  */
> +extern struct type callback_type;
> +
>   /* Test if a type is a union, either a plain one or a language
>      specific one.  */
>   #define UNION_P(x)					\
> --- gcc/gengtype.c.jj	2021-10-04 10:16:10.885140187 +0200
> +++ gcc/gengtype.c	2021-11-08 16:30:41.981750183 +0100
> @@ -172,6 +172,7 @@ dbgprint_count_type_at (const char *fil,
>     int nb_struct = 0, nb_union = 0, nb_array = 0, nb_pointer = 0;
>     int nb_lang_struct = 0;
>     int nb_user_struct = 0, nb_undefined = 0;
> +  int nb_callback = 0;
>     type_p p = NULL;
>     for (p = t; p; p = p->next)
>       {
> @@ -202,6 +203,9 @@ dbgprint_count_type_at (const char *fil,
>   	case TYPE_ARRAY:
>   	  nb_array++;
>   	  break;
> +	case TYPE_CALLBACK:
> +	  nb_callback++;
> +	  break;
>   	case TYPE_LANG_STRUCT:
>   	  nb_lang_struct++;
>   	  break;
> @@ -217,6 +221,8 @@ dbgprint_count_type_at (const char *fil,
>       fprintf (stderr, "@@%%@@ %d structs, %d unions\n", nb_struct, nb_union);
>     if (nb_pointer > 0 || nb_array > 0)
>       fprintf (stderr, "@@%%@@ %d pointers, %d arrays\n", nb_pointer, nb_array);
> +  if (nb_callback > 0)
> +    fprintf (stderr, "@@%%@@ %d callbacks\n", nb_callback);
>     if (nb_lang_struct > 0)
>       fprintf (stderr, "@@%%@@ %d lang_structs\n", nb_lang_struct);
>     if (nb_user_struct > 0)
> @@ -495,6 +501,10 @@ struct type scalar_char = {
>     TYPE_SCALAR, 0, 0, 0, GC_USED, {0}
>   };
>   
> +struct type callback_type = {
> +  TYPE_CALLBACK, 0, 0, 0, GC_USED, {0}
> +};
> +
>   /* Lists of various things.  */
>   
>   pair_p typedefs = NULL;
> @@ -1464,7 +1474,7 @@ static void set_gc_used (pair_p);
>   
>   static void
>   process_gc_options (options_p opt, enum gc_used_enum level, int *maybe_undef,
> -		    int *length, int *skip, type_p *nested_ptr)
> +		    int *length, int *skip, int *callback, type_p *nested_ptr)
>   {
>     options_p o;
>     for (o = opt; o; o = o->next)
> @@ -1478,6 +1488,8 @@ process_gc_options (options_p opt, enum
>         *length = 1;
>       else if (strcmp (o->name, "skip") == 0)
>         *skip = 1;
> +    else if (strcmp (o->name, "callback") == 0)
> +      *callback = 1;
>       else if (strcmp (o->name, "nested_ptr") == 0
>   	     && o->kind == OPTION_NESTED)
>         *nested_ptr = ((const struct nested_ptr_data *) o->info.nested)->type;
> @@ -1526,7 +1538,7 @@ set_gc_used_type (type_p t, enum gc_used
>   	type_p dummy2;
>   	bool allow_undefined_field_types = (t->kind == TYPE_USER_STRUCT);
>   
> -	process_gc_options (t->u.s.opt, level, &dummy, &dummy, &dummy,
> +	process_gc_options (t->u.s.opt, level, &dummy, &dummy, &dummy, &dummy,
>   			    &dummy2);
>   
>   	if (t->u.s.base_class)
> @@ -1542,9 +1554,10 @@ set_gc_used_type (type_p t, enum gc_used
>   	    int maybe_undef = 0;
>   	    int length = 0;
>   	    int skip = 0;
> +	    int callback = 0;
>   	    type_p nested_ptr = NULL;
>   	    process_gc_options (f->opt, level, &maybe_undef, &length, &skip,
> -				&nested_ptr);
> +				&callback, &nested_ptr);
>   
>   	    if (nested_ptr && f->type->kind == TYPE_POINTER)
>   	      set_gc_used_type (nested_ptr, GC_POINTED_TO);
> @@ -1554,6 +1567,8 @@ set_gc_used_type (type_p t, enum gc_used
>   	      set_gc_used_type (f->type->u.p, GC_MAYBE_POINTED_TO);
>   	    else if (skip)
>   	      ;			/* target type is not used through this field */
> +	    else if (callback)
> +	      f->type = &callback_type;
>   	    else
>   	      set_gc_used_type (f->type, GC_USED, allow_undefined_field_types);
>   	  }
> @@ -2519,6 +2534,7 @@ output_mangled_typename (outf_p of, cons
>         {
>         case TYPE_NONE:
>         case TYPE_UNDEFINED:
> +      case TYPE_CALLBACK:
>   	gcc_unreachable ();
>   	break;
>         case TYPE_POINTER:
> @@ -2719,6 +2735,8 @@ walk_type (type_p t, struct walk_type_da
>         ;
>       else if (strcmp (oo->name, "for_user") == 0)
>         ;
> +    else if (strcmp (oo->name, "callback") == 0)
> +      ;
>       else
>         error_at_line (d->line, "unknown option `%s'\n", oo->name);
>   
> @@ -2744,6 +2762,7 @@ walk_type (type_p t, struct walk_type_da
>       {
>       case TYPE_SCALAR:
>       case TYPE_STRING:
> +    case TYPE_CALLBACK:
>         d->process_field (t, d);
>         break;
>   
> @@ -3275,6 +3294,7 @@ write_types_process_field (type_p f, con
>         break;
>   
>       case TYPE_SCALAR:
> +    case TYPE_CALLBACK:
>         break;
>   
>       case TYPE_ARRAY:
> @@ -3820,6 +3840,7 @@ write_types_local_user_process_field (ty
>         break;
>   
>       case TYPE_SCALAR:
> +    case TYPE_CALLBACK:
>         break;
>   
>       case TYPE_ARRAY:
> @@ -3906,6 +3927,13 @@ write_types_local_process_field (type_p
>       case TYPE_SCALAR:
>         break;
>   
> +    case TYPE_CALLBACK:
> +      oprintf (d->of, "%*sif ((void *)(%s) == this_obj)\n", d->indent, "",
> +	       d->prev_val[3]);
> +      oprintf (d->of, "%*s  gt_pch_note_callback (&(%s), this_obj);\n",
> +	       d->indent, "", d->val);
> +      break;
> +
>       case TYPE_ARRAY:
>       case TYPE_NONE:
>       case TYPE_UNDEFINED:
> @@ -4434,6 +4462,7 @@ write_root (outf_p f, pair_p v, type_p t
>       case TYPE_UNDEFINED:
>       case TYPE_UNION:
>       case TYPE_LANG_STRUCT:
> +    case TYPE_CALLBACK:
>         error_at_line (line, "global `%s' is unimplemented type", name);
>       }
>   }
> @@ -4728,6 +4757,9 @@ dump_typekind (int indent, enum typekind
>       case TYPE_ARRAY:
>         printf ("TYPE_ARRAY");
>         break;
> +    case TYPE_CALLBACK:
> +      printf ("TYPE_CALLBACK");
> +      break;
>       case TYPE_LANG_STRUCT:
>         printf ("TYPE_LANG_STRUCT");
>         break;
> @@ -4894,6 +4926,7 @@ dump_type (int indent, type_p t)
>   	      t->u.scalar_is_char ? "true" : "false");
>         break;
>       case TYPE_STRING:
> +    case TYPE_CALLBACK:
>         break;
>       case TYPE_STRUCT:
>       case TYPE_UNION:
> --- gcc/varasm.c.jj	2021-09-28 11:34:29.343147261 +0200
> +++ gcc/varasm.c	2021-11-08 13:26:15.032606040 +0100
> @@ -250,8 +250,8 @@ object_block_hasher::hash (object_block
>   /* Return a new unnamed section with the given fields.  */
>   
>   section *
> -get_unnamed_section (unsigned int flags, void (*callback) (const void *),
> -		     const void *data)
> +get_unnamed_section (unsigned int flags, void (*callback) (const char *),
> +		     const char *data)
>   {
>     section *sect;
>   
> @@ -7778,9 +7778,9 @@ file_end_indicate_split_stack (void)
>      a get_unnamed_section callback.  */
>   
>   void
> -output_section_asm_op (const void *directive)
> +output_section_asm_op (const char *directive)
>   {
> -  fprintf (asm_out_file, "%s\n", (const char *) directive);
> +  fprintf (asm_out_file, "%s\n", directive);
>   }
>   
>   /* Emit assembly code to switch to section NEW_SECTION.  Do nothing if
> --- gcc/ggc-common.c.jj	2021-11-08 11:09:50.280318624 +0100
> +++ gcc/ggc-common.c	2021-11-17 20:10:07.088187637 +0100
> @@ -246,6 +246,7 @@ saving_hasher::equal (const ptr_data *p1
>   }
>   
>   static hash_table<saving_hasher> *saving_htab;
> +static vec<void *> callback_vec;
>   
>   /* Register an object in the hash table.  */
>   
> @@ -278,6 +279,23 @@ gt_pch_note_object (void *obj, void *not
>     return 1;
>   }
>   
> +/* Register address of a callback pointer.  */
> +void
> +gt_pch_note_callback (void *obj, void *base)
> +{
> +  void *ptr;
> +  memcpy (&ptr, obj, sizeof (void *));
> +  if (ptr != NULL)
> +    {
> +      struct ptr_data *data
> +	= (struct ptr_data *)
> +	  saving_htab->find_with_hash (base, POINTER_HASH (base));
> +      gcc_assert (data);
> +      callback_vec.safe_push ((char *) data->new_addr
> +			      + ((char *) obj - (char *) base));
> +    }
> +}
> +
>   /* Register an object in the hash table.  */
>   
>   void
> @@ -576,10 +594,20 @@ gt_pch_save (FILE *f)
>     ggc_pch_finish (state.d, state.f);
>     gt_pch_fixup_stringpool ();
>   
> +  unsigned num_callbacks = callback_vec.length ();
> +  void (*pch_save) (FILE *) = &gt_pch_save;
> +  if (fwrite (&pch_save, sizeof (pch_save), 1, f) != 1
> +      || fwrite (&num_callbacks, sizeof (num_callbacks), 1, f) != 1
> +      || (num_callbacks
> +	  && fwrite (callback_vec.address (), sizeof (void *), num_callbacks,
> +		     f) != num_callbacks))
> +    fatal_error (input_location, "cannot write PCH file: %m");
> +
>     XDELETE (state.ptrs);
>     XDELETE (this_object);
>     delete saving_htab;
>     saving_htab = NULL;
> +  callback_vec.release ();
>   }
>   
>   /* Read the state of the compiler back in from F.  */
> @@ -661,6 +689,30 @@ gt_pch_restore (FILE *f)
>   
>     gt_pch_restore_stringpool ();
>   
> +  void (*pch_save) (FILE *);
> +  unsigned num_callbacks;
> +  if (fread (&pch_save, sizeof (pch_save), 1, f) != 1
> +      || fread (&num_callbacks, sizeof (num_callbacks), 1, f) != 1)
> +    fatal_error (input_location, "cannot read PCH file: %m");
> +  if (pch_save != &gt_pch_save)
> +    {
> +      uintptr_t bias = (uintptr_t) &gt_pch_save - (uintptr_t) pch_save;
> +      void **ptrs = XNEWVEC (void *, num_callbacks);
> +      unsigned i;
> +
> +      if (fread (ptrs, sizeof (void *), num_callbacks, f) != num_callbacks)
> +	fatal_error (input_location, "cannot read PCH file: %m");
> +      for (i = 0; i < num_callbacks; ++i)
> +	{
> +	  memcpy (&pch_save, ptrs[i], sizeof (pch_save));
> +	  pch_save = (void (*) (FILE *)) ((uintptr_t) pch_save + bias);
> +	  memcpy (ptrs[i], &pch_save, sizeof (pch_save));
> +	}
> +      XDELETE (ptrs);
> +    }
> +  else if (fseek (f, num_callbacks * sizeof (void *), SEEK_CUR) != 0)
> +    fatal_error (input_location, "cannot read PCH file: %m");
> +
>     /* Barring corruption of the PCH file, the restored line table should be
>        complete and usable.  */
>     line_table = new_line_table;
> --- gcc/doc/gty.texi.jj	2021-08-19 11:42:27.363422428 +0200
> +++ gcc/doc/gty.texi	2021-11-08 17:13:46.613882767 +0100
> @@ -197,6 +197,15 @@ If @code{skip} is applied to a field, th
>   This is somewhat dangerous; the only safe use is in a union when one
>   field really isn't ever used.
>   
> +@findex callback
> +@item callback
> +
> +@code{callback} should be applied to fields with pointer to function type
> +and causes the field to be ignored similarly to @code{skip}, except when
> +writing PCH and the field is non-NULL it will remember the field's address
> +for relocation purposes if the process writing PCH has different load base
> +from a process reading PCH.
> +
>   @findex for_user
>   @item for_user
>   
> --- gcc/tree-core.h.jj	2021-11-04 12:27:02.377298411 +0100
> +++ gcc/tree-core.h	2021-11-08 13:24:04.496465555 +0100
> @@ -1964,7 +1964,7 @@ struct GTY(()) tree_function_decl {
>   struct GTY(()) tree_translation_unit_decl {
>     struct tree_decl_common common;
>     /* Source language of this translation unit.  Used for DWARF output.  */
> -  const char * GTY((skip(""))) language;
> +  const char *language;
>     /* TODO: Non-optimization used to build this translation unit.  */
>     /* TODO: Root of a partial DWARF tree for global types and decls.  */
>   };
> --- gcc/gengtype-state.c.jj	2021-07-20 10:08:09.891687732 +0200
> +++ gcc/gengtype-state.c	2021-11-08 15:19:16.157824146 +0100
> @@ -57,6 +57,7 @@ type_lineloc (const_type_p ty)
>       case TYPE_STRING:
>       case TYPE_POINTER:
>       case TYPE_ARRAY:
> +    case TYPE_CALLBACK:
>         return NULL;
>       default:
>         gcc_unreachable ();
> @@ -171,6 +172,7 @@ private:
>     void write_state_version (const char *version);
>     void write_state_scalar_type (type_p current);
>     void write_state_string_type (type_p current);
> +  void write_state_callback_type (type_p current);
>     void write_state_undefined_type (type_p current);
>     void write_state_struct_union_type (type_p current, const char *kindstr);
>     void write_state_struct_type (type_p current);
> @@ -898,6 +900,20 @@ state_writer::write_state_string_type (t
>       fatal ("Unexpected type in write_state_string_type");
>   }
>   
> +/* Write the callback type.  There is only one such thing! */
> +void
> +state_writer::write_state_callback_type (type_p current)
> +{
> +  if (current == &callback_type)
> +    {
> +      write_any_indent (0);
> +      fprintf (state_file, "callback ");
> +      write_state_common_type_content (current);
> +    }
> +  else
> +    fatal ("Unexpected type in write_state_callback_type");
> +}
> +
>   /* Write an undefined type.  */
>   void
>   state_writer::write_state_undefined_type (type_p current)
> @@ -1143,6 +1159,9 @@ state_writer::write_state_type (type_p c
>   	case TYPE_STRING:
>   	  write_state_string_type (current);
>   	  break;
> +	case TYPE_CALLBACK:
> +	  write_state_callback_type (current);
> +	  break;
>   	}
>       }
>   
> @@ -1477,6 +1496,14 @@ read_state_string_type (type_p *type)
>     read_state_common_type_content (*type);
>   }
>   
> +/* Read the callback_type.  */
> +static void
> +read_state_callback_type (type_p *type)
> +{
> +  *type = &callback_type;
> +  read_state_common_type_content (*type);
> +}
> +
>   
>   /* Read a lang_bitmap representing a set of GCC front-end languages.  */
>   static void
> @@ -1834,6 +1861,11 @@ read_state_type (type_p *current)
>   	      next_state_tokens (1);
>   	      read_state_string_type (current);
>   	    }
> +	  else if (state_token_is_name (t0, "callback"))
> +	    {
> +	      next_state_tokens (1);
> +	      read_state_callback_type (current);
> +	    }
>   	  else if (state_token_is_name (t0, "undefined"))
>   	    {
>   	      *current = XCNEW (struct type);
> --- gcc/output.h.jj	2021-09-28 11:34:29.235148754 +0200
> +++ gcc/output.h	2021-11-08 16:26:01.172755377 +0100
> @@ -470,7 +470,7 @@ struct GTY(()) named_section {
>   
>   /* A callback that writes the assembly code for switching to an unnamed
>      section.  The argument provides callback-specific data.  */
> -typedef void (*unnamed_section_callback) (const void *);
> +typedef void (*unnamed_section_callback) (const char *);
>   
>   /* Information about a SECTION_UNNAMED section.  */
>   struct GTY(()) unnamed_section {
> @@ -478,8 +478,8 @@ struct GTY(()) unnamed_section {
>   
>     /* The callback used to switch to the section, and the data that
>        should be passed to the callback.  */
> -  unnamed_section_callback GTY ((skip)) callback;
> -  const void *GTY ((skip)) data;
> +  unnamed_section_callback GTY ((callback)) callback;
> +  const char *data;
>   
>     /* The next entry in the chain of unnamed sections.  */
>     section *next;
> @@ -503,7 +503,7 @@ struct GTY(()) noswitch_section {
>     struct section_common common;
>   
>     /* The callback used to assemble decls in this section.  */
> -  noswitch_section_callback GTY ((skip)) callback;
> +  noswitch_section_callback GTY ((callback)) callback;
>   };
>   
>   /* Information about a section, which may be named or unnamed.  */
> @@ -538,8 +538,8 @@ extern GTY(()) section *bss_noswitch_sec
>   extern GTY(()) section *in_section;
>   extern GTY(()) bool in_cold_section_p;
>   
> -extern section *get_unnamed_section (unsigned int, void (*) (const void *),
> -				     const void *);
> +extern section *get_unnamed_section (unsigned int, void (*) (const char *),
> +				     const char *);
>   extern section *get_section (const char *, unsigned int, tree,
>   			     bool not_existing = false);
>   extern section *get_named_section (tree, const char *, int);
> @@ -561,7 +561,7 @@ extern section *get_cdtor_priority_secti
>   
>   extern bool unlikely_text_section_p (section *);
>   extern void switch_to_section (section *, tree = nullptr);
> -extern void output_section_asm_op (const void *);
> +extern void output_section_asm_op (const char *);
>   
>   extern void record_tm_clone_pair (tree, tree);
>   extern void finish_tm_clone_pairs (void);
> --- gcc/config/avr/avr.c.jj	2021-07-15 10:16:12.873583249 +0200
> +++ gcc/config/avr/avr.c	2021-11-08 13:28:30.215676387 +0100
> @@ -10114,10 +10114,9 @@ avr_output_bss_section_asm_op (const voi
>   /* Unnamed section callback for progmem*.data sections.  */
>   
>   static void
> -avr_output_progmem_section_asm_op (const void *data)
> +avr_output_progmem_section_asm_op (const char *data)
>   {
> -  fprintf (asm_out_file, "\t.section\t%s,\"a\",@progbits\n",
> -           (const char*) data);
> +  fprintf (asm_out_file, "\t.section\t%s,\"a\",@progbits\n", data);
>   }
>   
>   
> --- gcc/config/darwin.c.jj	2021-10-21 10:23:27.450834602 +0200
> +++ gcc/config/darwin.c	2021-11-08 13:27:19.106691421 +0100
> @@ -134,7 +134,7 @@ int emit_aligned_common = false;
>      DIRECTIVE is as for output_section_asm_op.  */
>   
>   static void
> -output_objc_section_asm_op (const void *directive)
> +output_objc_section_asm_op (const char *directive)
>   {
>     static bool been_here = false;
>   
> --- gcc/config/pa/pa.c.jj	2021-10-27 09:00:28.762277456 +0200
> +++ gcc/config/pa/pa.c	2021-11-08 13:29:41.935652629 +0100
> @@ -10011,7 +10011,7 @@ pa_arg_partial_bytes (cumulative_args_t
>      to the default text subspace.  */
>   
>   static void
> -som_output_text_section_asm_op (const void *data ATTRIBUTE_UNUSED)
> +som_output_text_section_asm_op (const char *data ATTRIBUTE_UNUSED)
>   {
>     gcc_assert (TARGET_SOM);
>     if (TARGET_GAS)
> @@ -10055,7 +10055,7 @@ som_output_text_section_asm_op (const vo
>      sections.  This function is only used with SOM.  */
>   
>   static void
> -som_output_comdat_data_section_asm_op (const void *data)
> +som_output_comdat_data_section_asm_op (const char *data)
>   {
>     in_section = NULL;
>     output_section_asm_op (data);
> --- gcc/config/rs6000/rs6000.c.jj	2021-11-05 00:43:22.476626062 +0100
> +++ gcc/config/rs6000/rs6000.c	2021-11-08 13:43:22.415940789 +0100
> @@ -20597,7 +20597,7 @@ rs6000_ms_bitfield_layout_p (const_tree
>   /* A get_unnamed_section callback, used for switching to toc_section.  */
>   
>   static void
> -rs6000_elf_output_toc_section_asm_op (const void *data ATTRIBUTE_UNUSED)
> +rs6000_elf_output_toc_section_asm_op (const char *data ATTRIBUTE_UNUSED)
>   {
>     if ((DEFAULT_ABI == ABI_AIX || DEFAULT_ABI == ABI_ELFv2)
>         && TARGET_MINIMAL_TOC)
> @@ -21301,35 +21301,39 @@ rs6000_xcoff_asm_globalize_label (FILE *
>      points to the section string variable.  */
>   
>   static void
> -rs6000_xcoff_output_readonly_section_asm_op (const void *directive)
> +rs6000_xcoff_output_readonly_section_asm_op (const char *directive)
>   {
>     fprintf (asm_out_file, "\t.csect %s[RO],%s\n",
> -	   *(const char *const *) directive,
> +	   directive
> +	   ? xcoff_private_rodata_section_name
> +	   : xcoff_read_only_section_name,
>   	   XCOFF_CSECT_DEFAULT_ALIGNMENT_STR);
>   }
>   
>   /* Likewise for read-write sections.  */
>   
>   static void
> -rs6000_xcoff_output_readwrite_section_asm_op (const void *directive)
> +rs6000_xcoff_output_readwrite_section_asm_op (const char *)
>   {
>     fprintf (asm_out_file, "\t.csect %s[RW],%s\n",
> -	   *(const char *const *) directive,
> +	   xcoff_private_data_section_name,
>   	   XCOFF_CSECT_DEFAULT_ALIGNMENT_STR);
>   }
>   
>   static void
> -rs6000_xcoff_output_tls_section_asm_op (const void *directive)
> +rs6000_xcoff_output_tls_section_asm_op (const char *directive)
>   {
>     fprintf (asm_out_file, "\t.csect %s[TL],%s\n",
> -	   *(const char *const *) directive,
> +	   directive
> +	   ? xcoff_private_data_section_name
> +	   : xcoff_tls_data_section_name,
>   	   XCOFF_CSECT_DEFAULT_ALIGNMENT_STR);
>   }
>   
>   /* A get_unnamed_section callback, used for switching to toc_section.  */
>   
>   static void
> -rs6000_xcoff_output_toc_section_asm_op (const void *data ATTRIBUTE_UNUSED)
> +rs6000_xcoff_output_toc_section_asm_op (const char *data ATTRIBUTE_UNUSED)
>   {
>     if (TARGET_MINIMAL_TOC)
>       {
> @@ -21356,26 +21360,26 @@ rs6000_xcoff_asm_init_sections (void)
>   {
>     read_only_data_section
>       = get_unnamed_section (0, rs6000_xcoff_output_readonly_section_asm_op,
> -			   &xcoff_read_only_section_name);
> +			   NULL);
>   
>     private_data_section
>       = get_unnamed_section (SECTION_WRITE,
>   			   rs6000_xcoff_output_readwrite_section_asm_op,
> -			   &xcoff_private_data_section_name);
> +			   NULL);
>   
>     read_only_private_data_section
>       = get_unnamed_section (0, rs6000_xcoff_output_readonly_section_asm_op,
> -			   &xcoff_private_rodata_section_name);
> +			   "");
>   
>     tls_data_section
>       = get_unnamed_section (SECTION_TLS,
>   			   rs6000_xcoff_output_tls_section_asm_op,
> -			   &xcoff_tls_data_section_name);
> +			   NULL);
>   
>     tls_private_data_section
>       = get_unnamed_section (SECTION_TLS,
>   			   rs6000_xcoff_output_tls_section_asm_op,
> -			   &xcoff_private_data_section_name);
> +			   "");
>   
>     toc_section
>       = get_unnamed_section (0, rs6000_xcoff_output_toc_section_asm_op, NULL);
> --- gcc/c-family/c-pch.c.jj	2021-06-02 10:08:14.149450407 +0200
> +++ gcc/c-family/c-pch.c	2021-11-08 17:34:17.302343697 +0100
> @@ -54,7 +54,6 @@ struct c_pch_validity
>   {
>     uint32_t pch_write_symbols;
>     signed char match[MATCH_SIZE];
> -  void (*pch_init) (void);
>     size_t target_data_length;
>   };
>   
> @@ -117,7 +116,6 @@ pch_init (void)
>   	gcc_assert (v.match[i] == *pch_matching[i].flag_var);
>         }
>     }
> -  v.pch_init = &pch_init;
>     target_validity = targetm.get_pch_validity (&v.target_data_length);
>   
>     if (fwrite (partial_pch, IDENT_LENGTH, 1, f) != 1
> @@ -278,19 +276,6 @@ c_common_valid_pch (cpp_reader *pfile, c
>   	}
>     }
>   
> -  /* If the text segment was not loaded at the same address as it was
> -     when the PCH file was created, function pointers loaded from the
> -     PCH will not be valid.  We could in theory remap all the function
> -     pointers, but no support for that exists at present.
> -     Since we have the same executable, it should only be necessary to
> -     check one function.  */
> -  if (v.pch_init != &pch_init)
> -    {
> -      cpp_warning (pfile, CPP_W_INVALID_PCH,
> -		   "%s: had text segment at different address", name);
> -      return 2;
> -    }
> -
>     /* Check the target-specific validity data.  */
>     {
>       void *this_file_data = xmalloc (v.target_data_length);
> --- libcpp/include/line-map.h.jj	2021-11-01 14:37:06.697853154 +0100
> +++ libcpp/include/line-map.h	2021-11-08 16:16:34.562837006 +0100
> @@ -803,11 +803,11 @@ public:
>     unsigned int max_column_hint;
>   
>     /* The allocator to use when resizing 'maps', defaults to xrealloc.  */
> -  line_map_realloc reallocator;
> +  line_map_realloc GTY((callback)) reallocator;
>   
>     /* The allocators' function used to know the actual size it
>        allocated, for a certain allocation size requested.  */
> -  line_map_round_alloc_size_func round_alloc_size;
> +  line_map_round_alloc_size_func GTY((callback)) round_alloc_size;
>   
>     struct location_adhoc_data_map location_adhoc_data_map;
>   
> 
> 
> 	Jakub
> 

Jakub, I think the patch broke avr-linux target:

g++  -fno-PIE -c   -g   -DIN_GCC  -DCROSS_DIRECTORY_STRUCTURE   -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wno-error=format-diag -Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -fno-common  -DHAVE_CONFIG_H -I. -I. -I/home/marxin/Programming/gcc/gcc -I/home/marxin/Programming/gcc/gcc/. -I/home/marxin/Programming/gcc/gcc/../include -I/home/marxin/Programming/gcc/gcc/../libcpp/include -I/home/marxin/Programming/gcc/gcc/../libcody  -I/home/marxin/Programming/gcc/gcc/../libdecnumber -I/home/marxin/Programming/gcc/gcc/../libdecnumber/dpd -I../libdecnumber -I/home/marxin/Programming/gcc/gcc/../libbacktrace   -o avr.o -MT avr.o -MMD -MP -MF ./.deps/avr.TPo /home/marxin/Programming/gcc/gcc/config/avr/avr.c
/home/marxin/Programming/gcc/gcc/config/avr/avr.c: In function ‘void avr_output_data_section_asm_op(const void*)’:
/home/marxin/Programming/gcc/gcc/config/avr/avr.c:10097:26: error: invalid conversion from ‘const void*’ to ‘const char*’ [-fpermissive]
10097 |   output_section_asm_op (data);
       |                          ^~~~
       |                          |
       |                          const void*
In file included from /home/marxin/Programming/gcc/gcc/config/avr/avr.c:49:
/home/marxin/Programming/gcc/gcc/output.h:564:36: note:   initializing argument 1 of ‘void output_section_asm_op(const char*)’
   564 | extern void output_section_asm_op (const char *);
       |                                    ^~~~~~~~~~~~
/home/marxin/Programming/gcc/gcc/config/avr/avr.c: In function ‘void avr_output_bss_section_asm_op(const void*)’:
/home/marxin/Programming/gcc/gcc/config/avr/avr.c:10110:26: error: invalid conversion from ‘const void*’ to ‘const char*’ [-fpermissive]
10110 |   output_section_asm_op (data);
       |                          ^~~~
       |                          |
       |                          const void*
In file included from /home/marxin/Programming/gcc/gcc/config/avr/avr.c:49:
/home/marxin/Programming/gcc/gcc/output.h:564:36: note:   initializing argument 1 of ‘void output_section_asm_op(const char*)’
   564 | extern void output_section_asm_op (const char *);
       |                                    ^~~~~~~~~~~~
/home/marxin/Programming/gcc/gcc/config/avr/avr.c: In function ‘void avr_asm_init_sections()’:
/home/marxin/Programming/gcc/gcc/config/avr/avr.c:10135:47: error: invalid conversion from ‘void (*)(const void*)’ to ‘unnamed_section_callback’ {aka ‘void (*)(const char*)’} [-fpermissive]
10135 |     readonly_data_section->unnamed.callback = avr_output_data_section_asm_op;
       |                                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       |                                               |
       |                                               void (*)(const void*)
/home/marxin/Programming/gcc/gcc/config/avr/avr.c:10136:36: error: invalid conversion from ‘void (*)(const void*)’ to ‘unnamed_section_callback’ {aka ‘void (*)(const char*)’} [-fpermissive]
10136 |   data_section->unnamed.callback = avr_output_data_section_asm_op;
       |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       |                                    |
       |                                    void (*)(const void*)
/home/marxin/Programming/gcc/gcc/config/avr/avr.c:10137:35: error: invalid conversion from ‘void (*)(const void*)’ to ‘unnamed_section_callback’ {aka ‘void (*)(const char*)’} [-fpermissive]
10137 |   bss_section->unnamed.callback = avr_output_bss_section_asm_op;
       |                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       |                                   |
       |                                   void (*)(const void*)
/home/marxin/Programming/gcc/gcc/config/avr/avr.c: In function ‘unsigned int avr_section_type_flags(tree, const char*, int)’:
/home/marxin/Programming/gcc/gcc/config/avr/avr.c:10197:21: warning: space followed by punctuation character ‘.’ [-Wformat-diag]
10197 |         warning (0, "only uninitialized variables can be placed in the "
       |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
10198 |                  ".noinit section");
       |                  ~~~~~~~~~~~~~~~~~
/home/marxin/Programming/gcc/gcc/config/avr/avr.c: At global scope:
/home/marxin/Programming/gcc/gcc/config/avr/avr.c:12765:1: warning: ‘void avr_asm_out_dtor(rtx, int)’ defined but not used [-Wunused-function]
12765 | avr_asm_out_dtor (rtx symbol, int priority)
       | ^~~~~~~~~~~~~~~~
/home/marxin/Programming/gcc/gcc/config/avr/avr.c:12755:1: warning: ‘void avr_asm_out_ctor(rtx, int)’ defined but not used [-Wunused-function]
12755 | avr_asm_out_ctor (rtx symbol, int priority)
       | ^~~~~~~~~~~~~~~~
make: *** [Makefile:2413: avr.o] Error 1

Cheers,
Martin