commit fe7c3ecff1f9c0520090a77fa824d8c5d9dbec12

Author: Jakub Jelinek <jakub@redhat.com>

Date:   Fri Dec 3 11:03:30 2021 +0100

    pch: Add support for PCH for relocatable executables [PR71934]

    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

    Here is 1), 2), 3) implemented.

    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.

    2021-12-03  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.

commit 4dc6d19222581c77a174d44d97507d234fb7e39b

Author: Jakub Jelinek <jakub@redhat.com>

Date:   Mon Dec 6 11:18:58 2021 +0100

    avr: Fix AVR build [PR71934]

    On Mon, Dec 06, 2021 at 11:00:30AM +0100, Martin Liška wrote:

    > 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-erro

    > /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]

    This patch fixes that.

    2021-12-06  Jakub Jelinek  <jakub@redhat.com>

            PR pch/71934

            * config/avr/avr.c (avr_output_data_section_asm_op,

            avr_output_bss_section_asm_op): Change argument type from const void *

            to const char *.

diff --git a/gcc/c-family/c-pch.c b/gcc/c-family/c-pch.c

index 5da60423354..2cafa1387bb 100644

--- a/gcc/c-family/c-pch.c

+++ b/gcc/c-family/c-pch.c

@@ -58,7 +58,6 @@ struct c_pch_validity

 {

   unsigned char debug_info_type;

   signed char match[MATCH_SIZE];

-  void (*pch_init) (void);

   size_t target_data_length;

 };

@@ -123,7 +122,6 @@ 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

@@ -287,20 +285,6 @@ 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)

-    {

-      if (cpp_get_options (pfile)->warn_invalid_pch)

-	cpp_error (pfile, CPP_DL_WARNING,

-		   "%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);

diff --git a/gcc/config/avr/avr.c b/gcc/config/avr/avr.c

index 200701a583c..6ba038881d6 100644

--- a/gcc/config/avr/avr.c

+++ b/gcc/config/avr/avr.c

@@ -10114,10 +10114,9 @@ avr_output_bss_section_asm_op (const void *data)

 /* 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);

 }

diff --git a/gcc/config/darwin.c b/gcc/config/darwin.c

index c5ba7927ce1..8ad5b26c980 100644

--- a/gcc/config/darwin.c

+++ b/gcc/config/darwin.c

@@ -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;

diff --git a/gcc/config/pa/pa.c b/gcc/config/pa/pa.c

index f22d25a4066..2b10ef34061 100644

--- a/gcc/config/pa/pa.c

+++ b/gcc/config/pa/pa.c

@@ -10009,7 +10009,7 @@ pa_arg_partial_bytes (cumulative_args_t cum_v, const function_arg_info &arg)

    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)

@@ -10053,7 +10053,7 @@ som_output_text_section_asm_op (const void *data ATTRIBUTE_UNUSED)

    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);

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c

index 945157b1c1a..34089743759 100644

--- a/gcc/config/rs6000/rs6000.c

+++ b/gcc/config/rs6000/rs6000.c

@@ -20599,7 +20599,7 @@ rs6000_ms_bitfield_layout_p (const_tree record_type)

 /* 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)

@@ -21303,35 +21303,39 @@ rs6000_xcoff_asm_globalize_label (FILE *stream, const char *name)

    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)

     {

@@ -21358,26 +21362,26 @@ 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);

diff --git a/gcc/doc/gty.texi b/gcc/doc/gty.texi

index b996ff2c44e..ca2c8404894 100644

--- a/gcc/doc/gty.texi

+++ b/gcc/doc/gty.texi

@@ -205,6 +205,15 @@ If @code{skip} is applied to a field, the type machinery will ignore it.

 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

diff --git a/gcc/gengtype-state.c b/gcc/gengtype-state.c

index ac9d536963f..36a96e84574 100644

--- a/gcc/gengtype-state.c

+++ b/gcc/gengtype-state.c

@@ -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 (type_p current)

     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 current)

 	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);

diff --git a/gcc/gengtype.c b/gcc/gengtype.c

index a77cfd92bfa..b9daaa43689 100644

--- a/gcc/gengtype.c

+++ b/gcc/gengtype.c

@@ -172,6 +172,7 @@ dbgprint_count_type_at (const char *fil, int lin, const char *msg, type_p t)

   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, int lin, const char *msg, type_p t)

 	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, int lin, const char *msg, type_p t)

     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 gc_used_enum level, int *maybe_undef,

       *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_enum level,

 	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_enum level,

 	    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_enum level,

 	      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, const_type_p t)

       {

       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_data *d)

       ;

     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_data *d)

     {

     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, const struct walk_type_data *d)

       break;

     case TYPE_SCALAR:

+    case TYPE_CALLBACK:

       break;

     case TYPE_ARRAY:

@@ -3820,6 +3840,7 @@ write_types_local_user_process_field (type_p f, const struct walk_type_data *d)

       break;

     case TYPE_SCALAR:

+    case TYPE_CALLBACK:

       break;

     case TYPE_ARRAY:

@@ -3906,6 +3927,13 @@ write_types_local_process_field (type_p f, const struct walk_type_data *d)

     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 type, const char *name, int has_length,

     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 kind)

     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:

diff --git a/gcc/gengtype.h b/gcc/gengtype.h

index 8a7a54957ea..8fa7064ca85 100644

--- a/gcc/gengtype.h

+++ b/gcc/gengtype.h

@@ -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)					\

diff --git a/gcc/ggc-common.c b/gcc/ggc-common.c

index b6abed1d9a2..7c998e95473 100644

--- a/gcc/ggc-common.c

+++ b/gcc/ggc-common.c

@@ -256,6 +256,7 @@ 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.  */

@@ -288,6 +289,23 @@ 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

@@ -582,10 +600,20 @@ 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.  */

@@ -639,6 +667,30 @@ gt_pch_restore (FILE *f)

   ggc_pch_read (f, mmi.preferred_base);

   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");

 }

 /* Default version of HOST_HOOKS_GT_PCH_GET_ADDRESS when mmap is not present.

diff --git a/gcc/ggc.h b/gcc/ggc.h

index 5e921d957fd..c005f7e0412 100644

--- a/gcc/ggc.h

+++ b/gcc/ggc.h

@@ -46,6 +46,10 @@ typedef void (*gt_handle_reorder) (void *, void *, gt_pointer_operator,

 /* 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);

diff --git a/gcc/output.h b/gcc/output.h

index 8f6f15308f4..4a23795bf7e 100644

--- a/gcc/output.h

+++ b/gcc/output.h

@@ -456,7 +456,7 @@ struct GTY(()) named_section {

 /* A callback that writes the assembly code for switching to an unnamed

    section.  The argument provides callback-specific data.  */