[Bug rtl-optimization/8361] [3.3/3.4/4.0 regression] C++ compile-time performance regression

["steven at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

------- Additional Comments From steven at gcc dot gnu dot org  2004-11-12 12:52 -------
GCC 3.4 (CVS today) takes 35s usr on my machine.
GCC 4.0 (CVS today) takes 46s usr on the same machine.

The difference is entirely in DOM, into-SSA and SSA-other
which is really also into-SSA:

			usr	sys	wall
dominator optimization	3.16	0.02	3.26
tree SSA rewrite	3.24	0.01	3.27
tree SSA other		3.47	0.09	3.40


Per-pass and cummulative time spent (top 10 only):
integration             1.09    2.30%   48.88%
tree PHI insertion      1.21    2.56%   51.44%
loop invariant motion   1.30    2.75%   54.18%
global alloc            1.30    2.75%   56.93%
CSE                     1.72    3.63%   60.56%
parser                  3.05    6.44%   67.00%
dominator optimization  3.16    6.68%   73.68%
tree SSA rewrite        3.24    6.84%   80.52%
tree SSA other          3.47    7.33%   87.85%
expand                  5.75    12.15%  100.00%


Flat profile:
                                                                               
                
Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total
 time   seconds   seconds    calls   s/call   s/call  name
  1.82      8.19     8.19 13878865     0.00     0.00  is_gimple_reg
  1.50     14.95     6.76     6594     0.00     0.00  synth_mult
  1.28     20.69     5.74 12785589     0.00     0.00  ggc_alloc_stat
  1.27     26.38     5.69  3433257     0.00     0.00  free_df_for_stmt
  1.25     32.01     5.63 16868123     0.00     0.00  bitmap_set_bit
  1.19     37.35     5.34  4846931     0.00     0.00  get_stmt_operands
  1.17     42.59     5.24    62034     0.00     0.00  alloc_page
  1.15     47.75     5.16     3559     0.00     0.01  compute_immediate_uses
  0.99     52.18     4.43  6408238     0.00     0.00  htab_find_slot_with_hash
  0.98     56.60     4.42  2104725     0.00     0.00  compute_immediate_uses_for_phi
  0.93     60.76     4.16   821051     0.00     0.00  gt_ggc_mx_lang_tree_node
  0.91     64.83     4.07  7802758     0.00     0.00  register_new_def
  0.90     68.87     4.04   951728     0.00     0.00  rewrite_stmt
  0.88     72.82     3.95 30035694     0.00     0.00  bitmap_bit_p
  0.84     76.61     3.79   574332     0.00     0.00  cse_insn
  0.81     80.26     3.65   196671     0.00     0.00  compute_global_livein
  0.81     83.91     3.65   177070     0.00     0.00  insert_phi_nodes_for
  0.81     87.54     3.63  2697441     0.00     0.00  for_each_rtx
  0.81     91.16     3.62  1079773     0.00     0.00  check_phi_redundancy

which is a different way of saying "all over the map" :-(



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8361