bitmap.c (bitmap_head::crashme): Define.

2018-12-06  Richard Biener  <rguenther@suse.de>

	* bitmap.c (bitmap_head::crashme): Define.
	* bitmap.h (bitmap_head): Add constexpr default constructor
	poisoning the obstack member.
	(bitmap_head::crashme): Declare.
	(bitmap_release): New function clearing a bitmap and poisoning
	the obstack member.
	* gengtype.c (main): Make it recognize CONSTEXPR.

	* lra-constraints.c (lra_inheritance): Use bitmap_release
	instead of bitmap_clear.

	* ira.c (ira): Work around class-memaccess warning.
	* regrename.c (create_new_chain): Likewise.

From-SVN: r266850

gcc/ChangeLog

+2018-12-06  Richard Biener  <rguenther@suse.de>
+
+	* bitmap.c (bitmap_head::crashme): Define.
+	* bitmap.h (bitmap_head): Add constexpr default constructor
+	poisoning the obstack member.
+	(bitmap_head::crashme): Declare.
+	(bitmap_release): New function clearing a bitmap and poisoning
+	the obstack member.
+	* gengtype.c (main): Make it recognize CONSTEXPR.
+	* lra-constraints.c (lra_inheritance): Use bitmap_release
+	instead of bitmap_clear.
+	* ira.c (ira): Work around class-memaccess warning.
+	* regrename.c (create_new_chain): Likewise.
+
 2018-12-06  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/85726

gcc/bitmap.c

@@ -26,6 +26,10 @@ along with GCC; see the file COPYING3.  If not see
 /* Memory allocation statistics purpose instance.  */
 mem_alloc_description<bitmap_usage> bitmap_mem_desc;
 
+/* Static zero-initialized bitmap obstack used for default initialization
+   of bitmap_head.  */
+bitmap_obstack bitmap_head::crashme;
+
 static bitmap_element *bitmap_tree_listify_from (bitmap, bitmap_element *);
 
 /* Register new bitmap.  */

gcc/bitmap.h

@@ -323,6 +323,12 @@ struct GTY((chain_next ("%h.next"), chain_prev ("%h.prev"))) bitmap_element {
    already pointed to by the chain started by first, so GTY((skip)) it.  */
 
 struct GTY(()) bitmap_head {
+  static bitmap_obstack crashme;
+  /* Poison obstack to not make it not a valid initialized GC bitmap.  */
+  CONSTEXPR bitmap_head()
+    : indx(0), tree_form(false), first(NULL), current(NULL),
+      obstack (&crashme)
+  {}
   /* Index of last element looked at.  */
   unsigned int indx;
   /* False if the bitmap is in list form; true if the bitmap is in tree form.
@@ -441,6 +447,18 @@ bitmap_initialize (bitmap head, bitmap_obstack *obstack CXX_MEM_STAT_INFO)
     bitmap_register (head PASS_MEM_STAT);
 }
 
+/* Release a bitmap (but not its head).  This is suitable for pairing with
+   bitmap_initialize.  */
+
+static inline void
+bitmap_release (bitmap head)
+{
+  bitmap_clear (head);
+  /* Poison the obstack pointer so the obstack can be safely released.
+     Do not zero it as the bitmap then becomes initialized GC.  */
+  head->obstack = &bitmap_head::crashme;
+}
+
 /* Allocate and free bitmaps from obstack, malloc and gc'd memory.  */
 extern bitmap bitmap_alloc (bitmap_obstack *obstack CXX_MEM_STAT_INFO);
 #define BITMAP_ALLOC bitmap_alloc

gcc/gengtype.c

@@ -5205,6 +5205,7 @@ main (int argc, char **argv)
       POS_HERE (do_scalar_typedef ("void", &pos));
       POS_HERE (do_scalar_typedef ("machine_mode", &pos));
       POS_HERE (do_scalar_typedef ("fixed_size_mode", &pos));
+      POS_HERE (do_scalar_typedef ("CONSTEXPR", &pos));
       POS_HERE (do_typedef ("PTR", 
 			    create_pointer (resolve_typedef ("void", &pos)),
 			    &pos));

gcc/ira.c

@@ -5417,7 +5417,7 @@ ira (FILE *f)
 	    = ((struct ira_spilled_reg_stack_slot *)
 	       ira_allocate (max_regno
 			     * sizeof (struct ira_spilled_reg_stack_slot)));
-	  memset (ira_spilled_reg_stack_slots, 0,
+	  memset ((void *)ira_spilled_reg_stack_slots, 0,
 		  max_regno * sizeof (struct ira_spilled_reg_stack_slot));
 	}
     }

gcc/lra-constraints.c

@@ -6651,11 +6651,11 @@ lra_inheritance (void)
 	   inherit_in_ebb.  */
 	update_ebb_live_info (BB_HEAD (start_bb), BB_END (bb));
     }
-  bitmap_clear (&ebb_global_regs);
-  bitmap_clear (&temp_bitmap);
-  bitmap_clear (&live_regs);
-  bitmap_clear (&invalid_invariant_regs);
-  bitmap_clear (&check_only_regs);
+  bitmap_release (&ebb_global_regs);
+  bitmap_release (&temp_bitmap);
+  bitmap_release (&live_regs);
+  bitmap_release (&invalid_invariant_regs);
+  bitmap_release (&check_only_regs);
   free (usage_insns);
 
   timevar_pop (TV_LRA_INHERITANCE);

gcc/regrename.c

@@ -231,7 +231,7 @@ create_new_chain (unsigned this_regno, unsigned this_nregs, rtx *loc,
   struct du_chain *this_du;
   int nregs;
 
-  memset (head, 0, sizeof *head);
+  memset ((void *)head, 0, sizeof *head);
   head->next_chain = open_chains;
   head->regno = this_regno;
   head->nregs = this_nregs;