Re: Add obstack for canonical file name hash table

[Jan Hubicka <hubicka at ucw dot cz>]

Hi,
here is updated patch. Now the hash is freed though it is not
extraordinarily large (for firefox about 20k entries which roughly
correspond to number of source files)

Bootstrapped/regtested x86_64-linux. OK?

	* lto-streamer-in.c: Include alloc-pool.h.
	(freeing_string_slot_hasher): Remove.
	(string_slot_allocator): New object allocator.
	(file_name_hash_table): Turn to hash_table<string_slot_hasher>.
	(file_name_obstack): New obstack.
	(canon_file_name): Allocate in obstack and allocator.
	(lto_reader_init): Initialize obstack and allocator.
	(lto_free_file_name_hash): New function.
	* lto-streamer.h (lto_free_file_name_hash): New.
	* lto.c (do_whole_program_analysis): Call lto_free_file_name_hash.
Index: lto-streamer-in.c
===================================================================
--- lto-streamer-in.c	(revision 277796)
+++ lto-streamer-in.c	(working copy)
@@ -42,21 +42,18 @@ along with GCC; see the file COPYING3.
 #include "cgraph.h"
 #include "cfgloop.h"
 #include "debug.h"
+#include "alloc-pool.h"
 
-
-struct freeing_string_slot_hasher : string_slot_hasher
-{
-  static inline void remove (value_type *);
-};
-
-inline void
-freeing_string_slot_hasher::remove (value_type *v)
-{
-  free (v);
-}
+/* Allocator used to hold string slot entries for line map streaming.  */
+static struct object_allocator<struct string_slot> *string_slot_allocator;
 
 /* The table to hold the file names.  */
-static hash_table<freeing_string_slot_hasher> *file_name_hash_table;
+static hash_table<string_slot_hasher> *file_name_hash_table;
+
+/* This obstack holds file names used in locators. Line map datastructures
+   points here and thus it needs to be kept allocated as long as linemaps
+   exists.  */
+static struct obstack file_name_obstack;
 
 
 /* Check that tag ACTUAL has one of the given values.  NUM_TAGS is the
@@ -113,8 +110,8 @@ canon_file_name (const char *string)
       char *saved_string;
       struct string_slot *new_slot;
 
-      saved_string = (char *) xmalloc (len + 1);
-      new_slot = XCNEW (struct string_slot);
+      saved_string = XOBNEWVEC (&file_name_obstack, char, len + 1);
+      new_slot = string_slot_allocator->allocate ();
       memcpy (saved_string, string, len + 1);
       new_slot->s = saved_string;
       new_slot->len = len;
@@ -1722,7 +1719,23 @@ lto_reader_init (void)
 {
   lto_streamer_init ();
   file_name_hash_table
-    = new hash_table<freeing_string_slot_hasher> (37);
+    = new hash_table<string_slot_hasher> (37);
+  string_slot_allocator = new object_allocator <struct string_slot>
+				("line map file name hash");
+  gcc_obstack_init (&file_name_obstack);
+}
+
+/* Free hash table used to stream in location file names.  */
+
+void
+lto_free_file_name_hash (void)
+{
+  delete file_name_hash_table;
+  file_name_hash_table = NULL;
+  delete string_slot_allocator;
+  string_slot_allocator = NULL;
+  /* file_name_obstack must stay allocated since it is referred to by
+     line map table.  */
 }
 
 
Index: lto-streamer.h
===================================================================
--- lto-streamer.h	(revision 277796)
+++ lto-streamer.h	(working copy)
@@ -874,6 +874,7 @@ extern void lto_streamer_hooks_init (voi
 /* In lto-streamer-in.c */
 extern void lto_input_cgraph (struct lto_file_decl_data *, const char *);
 extern void lto_reader_init (void);
+extern void lto_free_file_name_hash (void);
 extern void lto_input_function_body (struct lto_file_decl_data *,
 				     struct cgraph_node *,
Index: lto/lto.c
===================================================================
--- lto/lto.c	(revision 277796)
+++ lto/lto.c	(working copy)
@@ -475,6 +476,9 @@ do_whole_program_analysis (void)
   /* We are about to launch the final LTRANS phase, stop the WPA timer.  */
   timevar_pop (TV_WHOPR_WPA);
 
+  /* We are no longer going to stream in anything.  Free some memory.  */
+  lto_free_file_name_hash ();
+
   timevar_push (TV_WHOPR_PARTITIONING);
 
   gcc_assert (!dump_file);