small GC tweak

[Zack Weinberg]

When I was removing strings from the GC arena I missed one place where
we try to mark strings, because it was using ggc_mark_if_gcable
instead of ggc_mark_string.  This patch eliminates that place.  Since
that was the only user of ggc_mark_if_gcable, I've eliminated that
routine as well.

This should be a small performance improvement.  However I do not have
numbers (and the compiler seems to be getting slower, overall,
lately).

Bootstrapped i686-linux; ok to apply?  (after the branch?)

zw

	* ggc-common.c (ggc_mark_rtx_children): No need to mark 'S' or
	's' slots in RTXen.
	* ggc-page.c, ggc-simple.c (ggc_mark_if_gcable): Delete	function.
	* ggc.h (ggc_mark_if_gcable): Delete prototype.

===================================================================
Index: ggc-common.c
--- ggc-common.c	2000/11/17 17:31:08	1.34
+++ ggc-common.c	2001/01/16 16:34:08
@@ -1,5 +1,5 @@
 /* Simple garbage collection for the GNU compiler.
-   Copyright (C) 1999, 2000 Free Software Foundation, Inc.
+   Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
 
 This file is part of GNU CC.
 
@@ -276,9 +276,6 @@ ggc_mark_rtx_children (r)
 	      break;
 	    case 'V': case 'E':
 	      ggc_mark_rtvec (XVEC (r, i));
-	      break;
-	    case 'S': case 's':
-	      ggc_mark_if_gcable (XSTR (r, i));
 	      break;
 	    }
 	}
===================================================================
Index: ggc-page.c
--- ggc-page.c	2001/01/14 11:22:12	1.38
+++ ggc-page.c	2001/01/16 16:34:08
@@ -1001,16 +1001,6 @@ ggc_set_mark (p)
   return 0;
 }
 
-/* Mark P, but check first that it was allocated by the collector.  */
-
-void
-ggc_mark_if_gcable (p)
-     const void *p;
-{
-  if (p && ggc_allocated_p (p))
-    ggc_set_mark (p);
-}
-
 /* Return the size of the gc-able object P.  */
 
 size_t
===================================================================
Index: ggc-simple.c
--- ggc-simple.c	2000/11/17 06:05:15	1.36
+++ ggc-simple.c	2001/01/16 16:34:08
@@ -1,5 +1,5 @@
 /* Simple garbage collection for the GNU compiler.
-   Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
+   Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
 
    This file is part of GNU CC.
 
@@ -226,29 +226,6 @@ ggc_set_mark (p)
   G.objects += 1;
 
   return 0;
-}
-
-/* Mark a node, but check first to see that it's really gc-able memory.  */
-
-void
-ggc_mark_if_gcable (p)
-     const void *p;
-{
-  struct ggc_mem *x;
-
-  if (p == NULL)
-    return;
-
-  x = (struct ggc_mem *) ((const char *)p - offsetof (struct ggc_mem, u));
-  if (! tree_lookup (x))
-    return;
-
-  if (x->mark)
-    return;
-
-  x->mark = 1;
-  G.allocated += x->size;
-  G.objects += 1;
 }
 
 /* Return the size of the gc-able object P.  */
===================================================================
Index: ggc.h
--- ggc.h	2000/11/17 17:31:08	1.33
+++ ggc.h	2001/01/16 16:34:09
@@ -1,5 +1,5 @@
 /* Garbage collection for the GNU compiler.
-   Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
+   Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
 
 This file is part of GNU CC.
 
@@ -99,9 +99,6 @@ extern void ggc_mark_rtvec_children PARA
       ggc_set_mark (a__);			\
   } while (0)
 
-/* Mark, but only if it was allocated in collectable memory.  */
-extern void ggc_mark_if_gcable PARAMS ((const void *));
-
 /* A GC implementation must provide these functions.  */
 
 /* Initialize the garbage collector.   */
@@ -141,8 +138,8 @@ const char *ggc_alloc_string PARAMS ((co
 /* Make a copy of S, in GC-able memory.  */
 #define ggc_strdup(S) ggc_alloc_string((S), -1)
 
-/* Invoke the collector.  This is really just a hint, but in the case of
-   the simple collector, the only time it will happen.  */
+/* Invoke the collector.  Garbage collection occurs only when this
+   function is called, not during allocations.  */
 void ggc_collect PARAMS ((void));
 
 /* Actually set the mark on a particular region of memory, but don't