df-scan.c (struct df_scan_problem_data): Remove the mw_link_pool alloc pool.

2008-06-08  Steven Bosscher  <stevenb.gcc@gmail.com>

	* df-scan.c (struct df_scan_problem_data): Remove the
	mw_link_pool alloc pool.
	(df_scan_free_internal): Don't free it.
	(df_scan_alloc): Don't allocate it.
	* df.h (struct df_link): Update comment.

From-SVN: r136576

gcc/ChangeLog

+2008-06-08  Steven Bosscher  <stevenb.gcc@gmail.com>
+
+	* df-scan.c (struct df_scan_problem_data): Remove the
+	mw_link_pool alloc pool.
+	(df_scan_free_internal): Don't free it.
+	(df_scan_alloc): Don't allocate it.
+	* df.h (struct df_link): Update comment.
+
 2008-06-08  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* except.h: Correct checks for when SJLJ exceptions must be used.

gcc/df-scan.c

@@ -166,7 +166,6 @@ struct df_scan_problem_data
   alloc_pool insn_pool;
   alloc_pool reg_pool;
   alloc_pool mw_reg_pool;
-  alloc_pool mw_link_pool;
   bitmap_obstack reg_bitmaps;
   bitmap_obstack insn_bitmaps;
 };
@@ -221,7 +220,6 @@ df_scan_free_internal (void)
   free_alloc_pool (problem_data->insn_pool);
   free_alloc_pool (problem_data->reg_pool);
   free_alloc_pool (problem_data->mw_reg_pool);
-  free_alloc_pool (problem_data->mw_link_pool);
   bitmap_obstack_release (&problem_data->reg_bitmaps);
   bitmap_obstack_release (&problem_data->insn_bitmaps);
   free (df_scan->problem_data);
@@ -312,9 +310,6 @@ df_scan_alloc (bitmap all_blocks ATTRIBUTE_UNUSED)
   problem_data->mw_reg_pool 
     = create_alloc_pool ("df_scan_mw_reg pool", 
 			 sizeof (struct df_mw_hardreg), block_size);
-  problem_data->mw_link_pool 
-    = create_alloc_pool ("df_scan_mw_link pool", 
-			 sizeof (struct df_link), block_size);
 
   bitmap_obstack_initialize (&problem_data->reg_bitmaps);
   bitmap_obstack_initialize (&problem_data->insn_bitmaps);

gcc/df.h

@@ -409,9 +409,8 @@ struct df_ref_extract
   enum machine_mode mode;
 };
 
-/* These links are used for two purposes:
-   1) def-use or use-def chains. 
-   2) Multiword hard registers that underly a single hardware register.  */
+/* These links are used for ref-ref chains.  Currently only DEF-USE and
+   USE-DEF chains can be built by DF.  */
 struct df_link
 {
   struct df_ref *ref;