2003-11-09 Andrew Cagney <cagney@redhat.com>

	* arch-utils.c (gdbarch_update_p): New function.
	* gdbarch.sh (gdbarch_update_p): Delete function.
 	(find_arch_by_info, gdbarch_find_by_info): New functions.
	(deprecated_current_gdbarch_set_hack): New function.
	* gdbarch.c: Re-generate.

5 files changed, 285 insertions, 186 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 0af2e0d..192d830 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2003-11-09  Andrew Cagney  <cagney@redhat.com>
 
+	* arch-utils.c (gdbarch_update_p): New function.
+	* gdbarch.sh (gdbarch_update_p): Delete function.
+ 	(find_arch_by_info, gdbarch_find_by_info): New functions.
+	(deprecated_current_gdbarch_set_hack): New function.
+	* gdbarch.c: Re-generate.
+
 	* gdbarch.sh (clear_gdbarch_swap): Delete function.
 	(swapout_gdbarch_swap): Delete function.
 	(swapin_gdbarch_swap): Delete function.
diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c
index 9483b93..363e212 100644
--- a/gdb/arch-utils.c
+++ b/gdb/arch-utils.c
@@ -489,6 +489,45 @@ set_architecture (char *ignore_args, int from_tty, struct cmd_list_element *c)
   show_architecture (NULL, from_tty);
 }
 
+/* Try to select a global architecture that matches "info".  Return
+   non-zero if the attempt succeds.  */
+int
+gdbarch_update_p (struct gdbarch_info info)
+{
+  struct gdbarch *new_gdbarch = gdbarch_find_by_info (info);
+
+  /* If there no architecture by that name, reject the request.  */
+  if (new_gdbarch == NULL)
+    {
+      if (gdbarch_debug)
+	fprintf_unfiltered (gdb_stdlog, "gdbarch_update_p: "
+			    "Architecture not found\n");
+      return 0;
+    }
+
+  /* If it is the same old architecture, accept the request (but don't
+     swap anything).  */
+  if (new_gdbarch == current_gdbarch)
+    {
+      if (gdbarch_debug)
+	fprintf_unfiltered (gdb_stdlog, "gdbarch_update_p: "
+			    "Architecture 0x%08lx (%s) unchanged\n",
+			    (long) new_gdbarch,
+			    gdbarch_bfd_arch_info (new_gdbarch)->printable_name);
+      return 1;
+    }
+
+  /* It's a new architecture, swap it in.  */
+  if (gdbarch_debug)
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_update_p: "
+			"New architecture 0x%08lx (%s) selected\n",
+			(long) new_gdbarch,
+			gdbarch_bfd_arch_info (new_gdbarch)->printable_name);
+  deprecated_current_gdbarch_select_hack (new_gdbarch);
+
+  return 1;
+}
+
 /* FIXME: kettenis/20031124: Of the functions that follow, only
    gdbarch_from_bfd is supposed to survive.  The others will
    dissappear since in the future GDB will (hopefully) be truly
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 1c79c43..2d7683c 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -5899,19 +5899,24 @@ gdbarch_list_lookup_by_info (struct gdbarch_list *arches,
 }
 
 
-/* Update the current architecture. Return ZERO if the update request
-   failed. */
+/* Find an architecture that matches the specified INFO.  Create a new
+   architecture if needed.  Return that new architecture.  Assumes
+   that there is no current architecture.  */
 
-int
-gdbarch_update_p (struct gdbarch_info info)
+static struct gdbarch *
+find_arch_by_info (struct gdbarch *old_gdbarch, struct gdbarch_info info)
 {
   struct gdbarch *new_gdbarch;
-  struct gdbarch *old_gdbarch;
   struct gdbarch_registration *rego;
 
+  /* The existing architecture has been swapped out - all this code
+     works from a clean slate.  */
+  gdb_assert (current_gdbarch == NULL);
+
   /* Fill in missing parts of the INFO struct using a number of
-     sources: ``set ...''; INFOabfd supplied; existing target.  */
-  gdbarch_info_fill (current_gdbarch, &info);
+     sources: "set ..."; INFOabfd supplied; and the existing
+     architecture.  */
+  gdbarch_info_fill (old_gdbarch, &info);
 
   /* Must have found some sort of architecture. */
   gdb_assert (info.bfd_arch_info != NULL);
@@ -5919,28 +5924,28 @@ gdbarch_update_p (struct gdbarch_info info)
   if (gdbarch_debug)
     {
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.bfd_arch_info %s\n",
+			  "find_arch_by_info: info.bfd_arch_info %s\n",
 			  (info.bfd_arch_info != NULL
 			   ? info.bfd_arch_info->printable_name
 			   : "(null)"));
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.byte_order %d (%s)\n",
+			  "find_arch_by_info: info.byte_order %d (%s)\n",
 			  info.byte_order,
 			  (info.byte_order == BFD_ENDIAN_BIG ? "big"
 			   : info.byte_order == BFD_ENDIAN_LITTLE ? "little"
 			   : "default"));
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.osabi %d (%s)\n",
+			  "find_arch_by_info: info.osabi %d (%s)\n",
 			  info.osabi, gdbarch_osabi_name (info.osabi));
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.abfd 0x%lx\n",
+			  "find_arch_by_info: info.abfd 0x%lx\n",
 			  (long) info.abfd);
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.tdep_info 0x%lx\n",
+			  "find_arch_by_info: info.tdep_info 0x%lx\n",
 			  (long) info.tdep_info);
     }
 
-  /* Find the target that knows about this architecture. */
+  /* Find the tdep code that knows about this architecture.  */
   for (rego = gdbarch_registry;
        rego != NULL;
        rego = rego->next)
@@ -5949,82 +5954,61 @@ gdbarch_update_p (struct gdbarch_info info)
   if (rego == NULL)
     {
       if (gdbarch_debug)
-	fprintf_unfiltered (gdb_stdlog, "gdbarch_update: No matching architecture\n");
+	fprintf_unfiltered (gdb_stdlog, "find_arch_by_info: "
+			    "No matching architecture\n");
       return 0;
     }
 
-  /* Swap the data belonging to the old target out setting the
-     installed data to zero.  This stops the ->init() function trying
-     to refer to the previous architecture's global data structures.  */
-  current_gdbarch_swap_out_hack ();
-
-  /* Save the previously selected architecture, setting the global to
-     NULL.  This stops ->init() trying to use the previous
-     architecture's configuration.  The previous architecture may not
-     even be of the same architecture family.  The most recent
-     architecture of the same family is found at the head of the
-     rego->arches list.  */
-  old_gdbarch = current_gdbarch;
-  current_gdbarch = NULL;
-
-  /* Ask the target for a replacement architecture. */
+  /* Ask the tdep code for an architecture that matches "info".  */
   new_gdbarch = rego->init (info, rego->arches);
 
-  /* Did the target like it?  No. Reject the change and revert to the
-     old architecture.  */
+  /* Did the tdep code like it?  No.  Reject the change and revert to
+     the old architecture.  */
   if (new_gdbarch == NULL)
     {
       if (gdbarch_debug)
-	fprintf_unfiltered (gdb_stdlog, "gdbarch_update: Target rejected architecture\n");
-      current_gdbarch_swap_in_hack (old_gdbarch);
-      return 0;
+	fprintf_unfiltered (gdb_stdlog, "find_arch_by_info: "
+			    "Target rejected architecture\n");
+      return NULL;
     }
 
-  /* Did the architecture change?  No.  Oops, put the old architecture
-     back.  */
-  if (old_gdbarch == new_gdbarch)
+  /* Is this a pre-existing architecture (as determined by already
+     being initialized)?  Move it to the front of the architecture
+     list (keeping the list sorted Most Recently Used).  */
+  if (new_gdbarch->initialized_p)
     {
+      struct gdbarch_list **list;
+      struct gdbarch_list *this;
       if (gdbarch_debug)
-	fprintf_unfiltered (gdb_stdlog, "gdbarch_update: Architecture 0x%08lx (%s) unchanged\n",
+	fprintf_unfiltered (gdb_stdlog, "find_arch_by_info: "
+			    "Previous architecture 0x%08lx (%s) selected\n",
 			    (long) new_gdbarch,
 			    new_gdbarch->bfd_arch_info->printable_name);
-      current_gdbarch_swap_in_hack (old_gdbarch);
-      return 1;
+      /* Find the existing arch in the list.  */
+      for (list = &rego->arches;
+	   (*list) != NULL && (*list)->gdbarch != new_gdbarch;
+	   list = &(*list)->next);
+      /* It had better be in the list of architectures.  */
+      gdb_assert ((*list) != NULL && (*list)->gdbarch == new_gdbarch);
+      /* Unlink THIS.  */
+      this = (*list);
+      (*list) = this->next;
+      /* Insert THIS at the front.  */
+      this->next = rego->arches;
+      rego->arches = this;
+      /* Return it.  */
+      return new_gdbarch;
     }
 
-  /* Is this a pre-existing architecture?  Yes. Move it to the front
-     of the list of architectures (keeping the list sorted Most
-     Recently Used) and then copy it in.  */
-  {
-    struct gdbarch_list **list;
-    for (list = &rego->arches;
-	 (*list) != NULL;
-	 list = &(*list)->next)
-      {
-	if ((*list)->gdbarch == new_gdbarch)
-	  {
-	    struct gdbarch_list *this;
-	    if (gdbarch_debug)
-	      fprintf_unfiltered (gdb_stdlog,
-				  "gdbarch_update: Previous architecture 0x%08lx (%s) selected\n",
-				  (long) new_gdbarch,
-				  new_gdbarch->bfd_arch_info->printable_name);
-	    /* Unlink this.  */
-	    this = (*list);
-	    (*list) = this->next;
-	    /* Insert in the front.  */
-	    this->next = rego->arches;
-	    rego->arches = this;
-	    /* Copy the new architecture in.  */
-	    current_gdbarch_swap_in_hack (new_gdbarch);
-	    architecture_changed_event ();
-	    return 1;
-	  }
-      }
-  }
-
-  /* Prepend this new architecture to the architecture list (keep the
-     list sorted Most Recently Used).  */
+  /* It's a new architecture.  */
+  if (gdbarch_debug)
+    fprintf_unfiltered (gdb_stdlog, "find_arch_by_info: "
+			"New architecture 0x%08lx (%s) selected\n",
+			(long) new_gdbarch,
+			new_gdbarch->bfd_arch_info->printable_name);
+  
+  /* Insert the new architecture into the front of the architecture
+     list (keep the list sorted Most Recently Used).  */
   {
     struct gdbarch_list *this = XMALLOC (struct gdbarch_list);
     this->next = rego->arches;
@@ -6032,37 +6016,59 @@ gdbarch_update_p (struct gdbarch_info info)
     rego->arches = this;
   }    
 
-  /* Switch to this new architecture marking it initialized.  */
-  current_gdbarch = new_gdbarch;
-  current_gdbarch->initialized_p = 1;
-  if (gdbarch_debug)
-    {
-      fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: New architecture 0x%08lx (%s) selected\n",
-			  (long) new_gdbarch,
-			  new_gdbarch->bfd_arch_info->printable_name);
-    }
-  
   /* Check that the newly installed architecture is valid.  Plug in
      any post init values.  */
   new_gdbarch->dump_tdep = rego->dump_tdep;
   verify_gdbarch (new_gdbarch);
+  new_gdbarch->initialized_p = 1;
 
-  /* Initialize the per-architecture memory (swap) areas.
-     CURRENT_GDBARCH must be update before these modules are
-     called. */
+  /* Initialize any per-architecture swap areas.  This phase requires
+     a valid global CURRENT_GDBARCH.  Set it momentarially, and then
+     swap the entire architecture out.  */
+  current_gdbarch = new_gdbarch;
   current_gdbarch_swap_init_hack ();
-  
-  /* Initialize the per-architecture data.  CURRENT_GDBARCH
-     must be updated before these modules are called. */
-  architecture_changed_event ();
+  current_gdbarch_swap_out_hack ();
 
   if (gdbarch_debug)
-    gdbarch_dump (current_gdbarch, gdb_stdlog);
+    gdbarch_dump (new_gdbarch, gdb_stdlog);
 
-  return 1;
+  return new_gdbarch;
 }
 
+struct gdbarch *
+gdbarch_find_by_info (struct gdbarch_info info)
+{
+  /* Save the previously selected architecture, setting the global to
+     NULL.  This stops things like gdbarch->init() trying to use the
+     previous architecture's configuration.  The previous architecture
+     may not even be of the same architecture family.  The most recent
+     architecture of the same family is found at the head of the
+     rego->arches list.  */
+  struct gdbarch *old_gdbarch = current_gdbarch_swap_out_hack ();
+
+  /* Find the specified architecture.  */
+  struct gdbarch *new_gdbarch = find_arch_by_info (old_gdbarch, info);
+
+  /* Restore the existing architecture.  */
+  gdb_assert (current_gdbarch == NULL);
+  current_gdbarch_swap_in_hack (old_gdbarch);
+
+  return new_gdbarch;
+}
+
+/* Make the specified architecture current, swapping the existing one
+   out.  */
+
+void
+deprecated_current_gdbarch_select_hack (struct gdbarch *new_gdbarch)
+{
+  gdb_assert (new_gdbarch != NULL);
+  gdb_assert (current_gdbarch != NULL);
+  gdb_assert (new_gdbarch->initialized_p);
+  current_gdbarch_swap_out_hack ();
+  current_gdbarch_swap_in_hack (new_gdbarch);
+  architecture_changed_event ();
+}
 
 extern void _initialize_gdbarch (void);
 
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index 05fb41f..766c20c 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -2555,6 +2555,27 @@ extern void *gdbarch_obstack_zalloc (struct gdbarch *gdbarch, long size);
 extern int gdbarch_update_p (struct gdbarch_info info);
 
 
+/* Helper function.  Find an architecture matching info.
+
+   INFO should be initialized using gdbarch_info_init, relevant fields
+   set, and then finished using gdbarch_info_fill.
+
+   Returns the corresponding architecture, or NULL if no matching
+   architecture was found.  "current_gdbarch" is not updated.  */
+
+extern struct gdbarch *gdbarch_find_by_info (struct gdbarch_info info);
+
+
+/* Helper function.  Set the global "current_gdbarch" to "gdbarch".
+
+   FIXME: kettenis/20031124: Of the functions that follow, only
+   gdbarch_from_bfd is supposed to survive.  The others will
+   dissappear since in the future GDB will (hopefully) be truly
+   multi-arch.  However, for now we're still stuck with the concept of
+   a single active architecture.  */
+
+extern void deprecated_current_gdbarch_select_hack (struct gdbarch *gdbarch);
+
 
 /* Register per-architecture data-pointer.
 
diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index 16dcc29..bf2f855 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -1161,6 +1161,27 @@ extern void *gdbarch_obstack_zalloc (struct gdbarch *gdbarch, long size);
 extern int gdbarch_update_p (struct gdbarch_info info);
 
 
+/* Helper function.  Find an architecture matching info.
+
+   INFO should be initialized using gdbarch_info_init, relevant fields
+   set, and then finished using gdbarch_info_fill.
+
+   Returns the corresponding architecture, or NULL if no matching
+   architecture was found.  "current_gdbarch" is not updated.  */
+
+extern struct gdbarch *gdbarch_find_by_info (struct gdbarch_info info);
+
+
+/* Helper function.  Set the global "current_gdbarch" to "gdbarch".
+
+   FIXME: kettenis/20031124: Of the functions that follow, only
+   gdbarch_from_bfd is supposed to survive.  The others will
+   dissappear since in the future GDB will (hopefully) be truly
+   multi-arch.  However, for now we're still stuck with the concept of
+   a single active architecture.  */
+
+extern void deprecated_current_gdbarch_select_hack (struct gdbarch *gdbarch);
+
 
 /* Register per-architecture data-pointer.
 
@@ -2111,19 +2132,24 @@ gdbarch_list_lookup_by_info (struct gdbarch_list *arches,
 }
 
 
-/* Update the current architecture. Return ZERO if the update request
-   failed. */
+/* Find an architecture that matches the specified INFO.  Create a new
+   architecture if needed.  Return that new architecture.  Assumes
+   that there is no current architecture.  */
 
-int
-gdbarch_update_p (struct gdbarch_info info)
+static struct gdbarch *
+find_arch_by_info (struct gdbarch *old_gdbarch, struct gdbarch_info info)
 {
   struct gdbarch *new_gdbarch;
-  struct gdbarch *old_gdbarch;
   struct gdbarch_registration *rego;
 
+  /* The existing architecture has been swapped out - all this code
+     works from a clean slate.  */
+  gdb_assert (current_gdbarch == NULL);
+
   /* Fill in missing parts of the INFO struct using a number of
-     sources: \`\`set ...''; INFOabfd supplied; existing target.  */
-  gdbarch_info_fill (current_gdbarch, &info);
+     sources: "set ..."; INFOabfd supplied; and the existing
+     architecture.  */
+  gdbarch_info_fill (old_gdbarch, &info);
 
   /* Must have found some sort of architecture. */
   gdb_assert (info.bfd_arch_info != NULL);
@@ -2131,28 +2157,28 @@ gdbarch_update_p (struct gdbarch_info info)
   if (gdbarch_debug)
     {
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.bfd_arch_info %s\n",
+			  "find_arch_by_info: info.bfd_arch_info %s\n",
 			  (info.bfd_arch_info != NULL
 			   ? info.bfd_arch_info->printable_name
 			   : "(null)"));
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.byte_order %d (%s)\n",
+			  "find_arch_by_info: info.byte_order %d (%s)\n",
 			  info.byte_order,
 			  (info.byte_order == BFD_ENDIAN_BIG ? "big"
 			   : info.byte_order == BFD_ENDIAN_LITTLE ? "little"
 			   : "default"));
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.osabi %d (%s)\n",
+			  "find_arch_by_info: info.osabi %d (%s)\n",
 			  info.osabi, gdbarch_osabi_name (info.osabi));
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.abfd 0x%lx\n",
+			  "find_arch_by_info: info.abfd 0x%lx\n",
 			  (long) info.abfd);
       fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: info.tdep_info 0x%lx\n",
+			  "find_arch_by_info: info.tdep_info 0x%lx\n",
 			  (long) info.tdep_info);
     }
 
-  /* Find the target that knows about this architecture. */
+  /* Find the tdep code that knows about this architecture.  */
   for (rego = gdbarch_registry;
        rego != NULL;
        rego = rego->next)
@@ -2161,82 +2187,61 @@ gdbarch_update_p (struct gdbarch_info info)
   if (rego == NULL)
     {
       if (gdbarch_debug)
-	fprintf_unfiltered (gdb_stdlog, "gdbarch_update: No matching architecture\\n");
+	fprintf_unfiltered (gdb_stdlog, "find_arch_by_info: "
+			    "No matching architecture\n");
       return 0;
     }
 
-  /* Swap the data belonging to the old target out setting the
-     installed data to zero.  This stops the ->init() function trying
-     to refer to the previous architecture's global data structures.  */
-  current_gdbarch_swap_out_hack ();
-
-  /* Save the previously selected architecture, setting the global to
-     NULL.  This stops ->init() trying to use the previous
-     architecture's configuration.  The previous architecture may not
-     even be of the same architecture family.  The most recent
-     architecture of the same family is found at the head of the
-     rego->arches list.  */
-  old_gdbarch = current_gdbarch;
-  current_gdbarch = NULL;
-
-  /* Ask the target for a replacement architecture. */
+  /* Ask the tdep code for an architecture that matches "info".  */
   new_gdbarch = rego->init (info, rego->arches);
 
-  /* Did the target like it?  No. Reject the change and revert to the
-     old architecture.  */
+  /* Did the tdep code like it?  No.  Reject the change and revert to
+     the old architecture.  */
   if (new_gdbarch == NULL)
     {
       if (gdbarch_debug)
-	fprintf_unfiltered (gdb_stdlog, "gdbarch_update: Target rejected architecture\\n");
-      current_gdbarch_swap_in_hack (old_gdbarch);
-      return 0;
+	fprintf_unfiltered (gdb_stdlog, "find_arch_by_info: "
+			    "Target rejected architecture\n");
+      return NULL;
     }
 
-  /* Did the architecture change?  No.  Oops, put the old architecture
-     back.  */
-  if (old_gdbarch == new_gdbarch)
+  /* Is this a pre-existing architecture (as determined by already
+     being initialized)?  Move it to the front of the architecture
+     list (keeping the list sorted Most Recently Used).  */
+  if (new_gdbarch->initialized_p)
     {
+      struct gdbarch_list **list;
+      struct gdbarch_list *this;
       if (gdbarch_debug)
-	fprintf_unfiltered (gdb_stdlog, "gdbarch_update: Architecture 0x%08lx (%s) unchanged\\n",
+	fprintf_unfiltered (gdb_stdlog, "find_arch_by_info: "
+			    "Previous architecture 0x%08lx (%s) selected\n",
 			    (long) new_gdbarch,
 			    new_gdbarch->bfd_arch_info->printable_name);
-      current_gdbarch_swap_in_hack (old_gdbarch);
-      return 1;
+      /* Find the existing arch in the list.  */
+      for (list = &rego->arches;
+	   (*list) != NULL && (*list)->gdbarch != new_gdbarch;
+	   list = &(*list)->next);
+      /* It had better be in the list of architectures.  */
+      gdb_assert ((*list) != NULL && (*list)->gdbarch == new_gdbarch);
+      /* Unlink THIS.  */
+      this = (*list);
+      (*list) = this->next;
+      /* Insert THIS at the front.  */
+      this->next = rego->arches;
+      rego->arches = this;
+      /* Return it.  */
+      return new_gdbarch;
     }
 
-  /* Is this a pre-existing architecture?  Yes. Move it to the front
-     of the list of architectures (keeping the list sorted Most
-     Recently Used) and then copy it in.  */
-  {
-    struct gdbarch_list **list;
-    for (list = &rego->arches;
-	 (*list) != NULL;
-	 list = &(*list)->next)
-      {
-	if ((*list)->gdbarch == new_gdbarch)
-	  {
-	    struct gdbarch_list *this;
-	    if (gdbarch_debug)
-	      fprintf_unfiltered (gdb_stdlog,
-				  "gdbarch_update: Previous architecture 0x%08lx (%s) selected\n",
-				  (long) new_gdbarch,
-				  new_gdbarch->bfd_arch_info->printable_name);
-	    /* Unlink this.  */
-	    this = (*list);
-	    (*list) = this->next;
-	    /* Insert in the front.  */
-	    this->next = rego->arches;
-	    rego->arches = this;
-	    /* Copy the new architecture in.  */
-	    current_gdbarch_swap_in_hack (new_gdbarch);
-	    architecture_changed_event ();
-	    return 1;
-	  }
-      }
-  }
-
-  /* Prepend this new architecture to the architecture list (keep the
-     list sorted Most Recently Used).  */
+  /* It's a new architecture.  */
+  if (gdbarch_debug)
+    fprintf_unfiltered (gdb_stdlog, "find_arch_by_info: "
+			"New architecture 0x%08lx (%s) selected\n",
+			(long) new_gdbarch,
+			new_gdbarch->bfd_arch_info->printable_name);
+  
+  /* Insert the new architecture into the front of the architecture
+     list (keep the list sorted Most Recently Used).  */
   {
     struct gdbarch_list *this = XMALLOC (struct gdbarch_list);
     this->next = rego->arches;
@@ -2244,37 +2249,59 @@ gdbarch_update_p (struct gdbarch_info info)
     rego->arches = this;
   }    
 
-  /* Switch to this new architecture marking it initialized.  */
-  current_gdbarch = new_gdbarch;
-  current_gdbarch->initialized_p = 1;
-  if (gdbarch_debug)
-    {
-      fprintf_unfiltered (gdb_stdlog,
-			  "gdbarch_update: New architecture 0x%08lx (%s) selected\\n",
-			  (long) new_gdbarch,
-			  new_gdbarch->bfd_arch_info->printable_name);
-    }
-  
   /* Check that the newly installed architecture is valid.  Plug in
      any post init values.  */
   new_gdbarch->dump_tdep = rego->dump_tdep;
   verify_gdbarch (new_gdbarch);
+  new_gdbarch->initialized_p = 1;
 
-  /* Initialize the per-architecture memory (swap) areas.
-     CURRENT_GDBARCH must be update before these modules are
-     called. */
+  /* Initialize any per-architecture swap areas.  This phase requires
+     a valid global CURRENT_GDBARCH.  Set it momentarially, and then
+     swap the entire architecture out.  */
+  current_gdbarch = new_gdbarch;
   current_gdbarch_swap_init_hack ();
-  
-  /* Initialize the per-architecture data.  CURRENT_GDBARCH
-     must be updated before these modules are called. */
-  architecture_changed_event ();
+  current_gdbarch_swap_out_hack ();
 
   if (gdbarch_debug)
-    gdbarch_dump (current_gdbarch, gdb_stdlog);
+    gdbarch_dump (new_gdbarch, gdb_stdlog);
+
+  return new_gdbarch;
+}
+
+struct gdbarch *
+gdbarch_find_by_info (struct gdbarch_info info)
+{
+  /* Save the previously selected architecture, setting the global to
+     NULL.  This stops things like gdbarch->init() trying to use the
+     previous architecture's configuration.  The previous architecture
+     may not even be of the same architecture family.  The most recent
+     architecture of the same family is found at the head of the
+     rego->arches list.  */
+  struct gdbarch *old_gdbarch = current_gdbarch_swap_out_hack ();
+
+  /* Find the specified architecture.  */
+  struct gdbarch *new_gdbarch = find_arch_by_info (old_gdbarch, info);
+
+  /* Restore the existing architecture.  */
+  gdb_assert (current_gdbarch == NULL);
+  current_gdbarch_swap_in_hack (old_gdbarch);
 
-  return 1;
+  return new_gdbarch;
 }
 
+/* Make the specified architecture current, swapping the existing one
+   out.  */
+
+void
+deprecated_current_gdbarch_select_hack (struct gdbarch *new_gdbarch)
+{
+  gdb_assert (new_gdbarch != NULL);
+  gdb_assert (current_gdbarch != NULL);
+  gdb_assert (new_gdbarch->initialized_p);
+  current_gdbarch_swap_out_hack ();
+  current_gdbarch_swap_in_hack (new_gdbarch);
+  architecture_changed_event ();
+}
 
 extern void _initialize_gdbarch (void);