RFA: Add a target_globals destructor

[Richard Sandiford <richard dot sandiford at arm dot com>]

This is a prerequisite for a cleaned-up version of the patch in:
https://gcc.gnu.org/ml/gcc/2014-03/msg00163.html .  Thanks to Trevor's
recent(ish) changes, it's now possible for GC structures to have
destructors.  This means that we can go back to xmalloc()ing the parts
of target_globals that don't point to GCed data.

Also, some non-GC default_* variables had redundant GTY markers.

Tested on x86_64-linux-gnu.  OK to install?

Richard


gcc/
	* bb-reorder.h (default_target_bb_reorder): Remove redundant GTY.
	* builtins.h (default_target_builtins): Likewise.
	* gcse.h (default_target_gcse): Likewise.
	* target-globals.h (target_globals): Add a destructor.  Convert
	void-pointer fields back to their real type and change from
	GTY((atomic)) to GTY((skip)).
	(restore_target_globals): Remove casts accordingly.
	* target-globals.c (save_target_globals): Use XCNEW rather than
	ggc_internal_cleared_alloc to allocate non-GC structures.
	Use ggc_cleared_alloc to allocate the target_globals structure
	itself.
	(target_globals::~target_globals): Define.

Index: gcc/bb-reorder.h
===================================================================
--- gcc/bb-reorder.h	2014-09-05 16:07:26.791345611 +0100
+++ gcc/bb-reorder.h	2014-09-05 16:07:26.787345661 +0100
@@ -26,7 +26,7 @@ struct target_bb_reorder {
   int x_uncond_jump_length;
 };
 
-extern GTY(()) struct target_bb_reorder default_target_bb_reorder;
+extern struct target_bb_reorder default_target_bb_reorder;
 #if SWITCHABLE_TARGET
 extern struct target_bb_reorder *this_target_bb_reorder;
 #else
Index: gcc/builtins.h
===================================================================
--- gcc/builtins.h	2014-09-05 16:07:26.791345611 +0100
+++ gcc/builtins.h	2014-09-05 16:07:26.787345661 +0100
@@ -39,7 +39,7 @@ struct target_builtins {
   enum machine_mode x_apply_result_mode[FIRST_PSEUDO_REGISTER];
 };
 
-extern GTY(()) struct target_builtins default_target_builtins;
+extern struct target_builtins default_target_builtins;
 #if SWITCHABLE_TARGET
 extern struct target_builtins *this_target_builtins;
 #else
Index: gcc/gcse.h
===================================================================
--- gcc/gcse.h	2014-09-05 16:07:26.791345611 +0100
+++ gcc/gcse.h	2014-09-05 16:07:26.787345661 +0100
@@ -32,7 +32,7 @@ struct target_gcse {
   bool x_can_copy_init_p;
 };
 
-extern GTY(()) struct target_gcse default_target_gcse;
+extern struct target_gcse default_target_gcse;
 #if SWITCHABLE_TARGET
 extern struct target_gcse *this_target_gcse;
 #else
Index: gcc/target-globals.h
===================================================================
--- gcc/target-globals.h	2014-09-05 16:07:26.791345611 +0100
+++ gcc/target-globals.h	2014-09-05 16:07:26.787345661 +0100
@@ -40,18 +40,20 @@ #define TARGET_GLOBALS_H 1
 #endif
 
 struct GTY(()) target_globals {
+  ~target_globals ();
+
   struct target_flag_state *GTY((skip)) flag_state;
-  void *GTY((atomic)) regs;
+  struct target_regs *GTY((skip)) regs;
   struct target_rtl *rtl;
-  void *GTY((atomic)) recog;
-  void *GTY((atomic)) hard_regs;
-  void *GTY((atomic)) reload;
-  void *GTY((atomic)) expmed;
+  struct target_recog *GTY((skip)) recog;
+  struct target_hard_regs *GTY((skip)) hard_regs;
+  struct target_reload *GTY((skip)) reload;
+  struct target_expmed *GTY((skip)) expmed;
   struct target_optabs *GTY((skip)) optabs;
   struct target_libfuncs *libfuncs;
   struct target_cfgloop *GTY((skip)) cfgloop;
-  void *GTY((atomic)) ira;
-  void *GTY((atomic)) ira_int;
+  struct target_ira *GTY((skip)) ira;
+  struct target_ira_int *GTY((skip)) ira_int;
   struct target_builtins *GTY((skip)) builtins;
   struct target_gcse *GTY((skip)) gcse;
   struct target_bb_reorder *GTY((skip)) bb_reorder;
@@ -68,17 +70,17 @@ extern struct target_globals *save_targe
 restore_target_globals (struct target_globals *g)
 {
   this_target_flag_state = g->flag_state;
-  this_target_regs = (struct target_regs *) g->regs;
+  this_target_regs = g->regs;
   this_target_rtl = g->rtl;
-  this_target_recog = (struct target_recog *) g->recog;
-  this_target_hard_regs = (struct target_hard_regs *) g->hard_regs;
-  this_target_reload = (struct target_reload *) g->reload;
-  this_target_expmed = (struct target_expmed *) g->expmed;
+  this_target_recog = g->recog;
+  this_target_hard_regs = g->hard_regs;
+  this_target_reload = g->reload;
+  this_target_expmed = g->expmed;
   this_target_optabs = g->optabs;
   this_target_libfuncs = g->libfuncs;
   this_target_cfgloop = g->cfgloop;
-  this_target_ira = (struct target_ira *) g->ira;
-  this_target_ira_int = (struct target_ira_int *) g->ira_int;
+  this_target_ira = g->ira;
+  this_target_ira_int = g->ira_int;
   this_target_builtins = g->builtins;
   this_target_gcse = g->gcse;
   this_target_bb_reorder = g->bb_reorder;
Index: gcc/target-globals.c
===================================================================
--- gcc/target-globals.c	2014-09-05 16:07:26.791345611 +0100
+++ gcc/target-globals.c	2014-09-05 16:15:31.769306144 +0100
@@ -67,37 +67,23 @@ struct target_globals default_target_glo
 struct target_globals *
 save_target_globals (void)
 {
-  struct target_globals *g;
-  struct target_globals_extra {
-    struct target_globals g;
-    struct target_flag_state flag_state;
-    struct target_optabs optabs;
-    struct target_cfgloop cfgloop;
-    struct target_builtins builtins;
-    struct target_gcse gcse;
-    struct target_bb_reorder bb_reorder;
-    struct target_lower_subreg lower_subreg;
-  } *p;
-  p = (struct target_globals_extra *)
-      ggc_internal_cleared_alloc (sizeof (struct target_globals_extra));
-  g = (struct target_globals *) p;
-  g->flag_state = &p->flag_state;
-  g->regs = ggc_internal_cleared_alloc (sizeof (struct target_regs));
+  struct target_globals *g = ggc_cleared_alloc <target_globals> ();
+  g->flag_state = XCNEW (struct target_flag_state);
+  g->regs = XCNEW (struct target_regs);
   g->rtl = ggc_cleared_alloc<target_rtl> ();
-  g->recog = ggc_internal_cleared_alloc (sizeof (struct target_recog));
-  g->hard_regs
-    = ggc_internal_cleared_alloc (sizeof (struct target_hard_regs));
-  g->reload = ggc_internal_cleared_alloc (sizeof (struct target_reload));
-  g->expmed =  ggc_internal_cleared_alloc (sizeof (struct target_expmed));
-  g->optabs = &p->optabs;
+  g->recog = XCNEW (struct target_recog);
+  g->hard_regs = XCNEW (struct target_hard_regs);
+  g->reload = XCNEW (struct target_reload);
+  g->expmed = XCNEW (struct target_expmed);
+  g->optabs = XCNEW (struct target_optabs);
   g->libfuncs = ggc_cleared_alloc<target_libfuncs> ();
-  g->cfgloop = &p->cfgloop;
-  g->ira = ggc_internal_cleared_alloc (sizeof (struct target_ira));
-  g->ira_int = ggc_internal_cleared_alloc (sizeof (struct target_ira_int));
-  g->builtins = &p->builtins;
-  g->gcse = &p->gcse;
-  g->bb_reorder = &p->bb_reorder;
-  g->lower_subreg = &p->lower_subreg;
+  g->cfgloop = XCNEW (struct target_cfgloop);
+  g->ira = XCNEW (struct target_ira);
+  g->ira_int = XCNEW (struct target_ira_int);
+  g->builtins = XCNEW (struct target_builtins);
+  g->gcse = XCNEW (struct target_gcse);
+  g->bb_reorder = XCNEW (struct target_bb_reorder);
+  g->lower_subreg = XCNEW (struct target_lower_subreg);
   restore_target_globals (g);
   init_reg_sets ();
   target_reinit ();
@@ -133,4 +119,26 @@ save_target_globals_default_opts ()
   return save_target_globals ();
 }
 
+target_globals::~target_globals ()
+{
+  /* default_target_globals points to static data so shouldn't be freed.  */
+  if (this != &default_target_globals)
+    {
+      XDELETE (flag_state);
+      XDELETE (regs);
+      XDELETE (recog);
+      XDELETE (hard_regs);
+      XDELETE (reload);
+      XDELETE (expmed);
+      XDELETE (optabs);
+      XDELETE (cfgloop);
+      XDELETE (ira);
+      XDELETE (ira_int);
+      XDELETE (builtins);
+      XDELETE (gcse);
+      XDELETE (bb_reorder);
+      XDELETE (lower_subreg);
+    }
+}
+
 #endif