[PATCH] More GC tuning

[Richard Guenther]

This shaves off another 50% of GC overhead, 2.5% garbage and 1% peak
memory usage (ia32, 1GB ram, tramp3d-v4 at -O).  In detail:

By adding var_ann_d and tree_ssa_name to the special bucket sizes, we reduce
overall GC garbage and overhead significantly for tramp3d-v4.  Before the
patch:

source location                                     Garbage            Freed             Leak         Overhead            Times
bitmap.c:139 (bitmap_element_allocate)             13272372: 1.2%          0: 0.0%          0: 0.0%    1474708: 3.6%     368677
tree-dfa.c:145 (create_var_ann)                           0: 0.0%   48905940:23.2%          0: 0.0%    6520792:16.0%     815099
tree-phinodes.c:156 (allocate_phi_node)            18612352: 1.6%          0: 0.0%          0: 0.0%    2025856: 5.0%     125470
tree-ssanames.c:147 (make_ssa_name)                55504624: 4.9%          0: 0.0%        112: 0.0%    3964624: 9.8%     991156
Total                                            1132100042        210957962         98903676         40652228         34797258

After the patch:

bitmap.c:139 (bitmap_element_allocate)             10336200: 0.9%          0: 0.0%          0: 0.0%          0: 0.0%     369150
tree-dfa.c:145 (create_var_ann)                           0: 0.0%   35864356:18.1%          0: 0.0%          0: 0.0%     815099
tree-phinodes.c:156 (allocate_phi_node)            14764096: 1.3%          0: 0.0%          0: 0.0%      70592: 0.4%     126026
tree-ssanames.c:159 (make_ssa_name)                47575392: 4.3%          0: 0.0%         96: 0.0%          0: 0.0%     991156
Total                                            1104637526        197754522         96300292         18962860         34798438

Note the drop in GC overhead and total garbage.  Peak virtual memory usage
for -O compile of tramp3d on a 32bit arch with 1GB ram dropped from 496802kB
to 490802kB.

Bootstrapped and tested on x86_64-unknown-linux-gnu.

Ok for mainline?

Thanks,
Richard.


2006-06-19  Richard Guenther  <rguenther@suse.de>

	* ggc-page.c (extra_order_size_table): Add var_ann_d,
	tree_ssa_name, bitmap_element and phi_node with 4 arguments
	sizes.

Index: ggc-page.c
===================================================================
*** ggc-page.c	(revision 114807)
--- ggc-page.c	(working copy)
*************** Software Foundation, 51 Franklin Street,
*** 186,198 ****
--- 186,204 ----
  
  static const size_t extra_order_size_table[] = {
    sizeof (struct stmt_ann_d),
+   sizeof (struct var_ann_d),
    sizeof (struct tree_decl_non_common),
    sizeof (struct tree_field_decl),
    sizeof (struct tree_parm_decl),
    sizeof (struct tree_var_decl),
    sizeof (struct tree_list),
+   sizeof (struct tree_ssa_name),
    sizeof (struct function),
    sizeof (struct basic_block_def),
+   sizeof (bitmap_element),
+   /* PHI nodes with one to three arguments are already covered by the
+      above sizes.  */
+   sizeof (struct tree_phi_node) + sizeof (struct phi_arg_d) * 3,
    TREE_EXP_SIZE (2),
    RTL_SIZE (2),			/* MEM, PLUS, etc.  */
    RTL_SIZE (9),			/* INSN */