Massive performance regression from switching to gcc 4.5

[Jan Hubicka]

... and time report
Execution times (seconds)
 garbage collection    :  12.48 ( 2%) usr   0.00 ( 0%) sys  12.50 ( 2%) wall       0 kB ( 0%) ggc
 callgraph optimization:   0.21 ( 0%) usr   0.00 ( 0%) sys   0.21 ( 0%) wall    2743 kB ( 0%) ggc
 varpool construction  :   0.97 ( 0%) usr   0.02 ( 0%) sys   0.97 ( 0%) wall   44476 kB ( 1%) ggc
 ipa cp                :   2.82 ( 0%) usr   0.05 ( 0%) sys   2.90 ( 0%) wall   65189 kB ( 2%) ggc
 ipa lto gimple in     :   4.96 ( 1%) usr   0.30 ( 2%) sys   5.28 ( 1%) wall       8 kB ( 0%) ggc
 ipa lto gimple out    :  26.51 ( 4%) usr   0.73 ( 4%) sys  27.54 ( 4%) wall       0 kB ( 0%) ggc
 ipa lto decl in       : 100.69 (14%) usr   2.76 (15%) sys 103.69 (14%) wall 3069230 kB (87%) ggc
 ipa lto decl out      : 405.60 (55%) usr   0.05 ( 0%) sys 406.86 (54%) wall       0 kB ( 0%) ggc
 ipa lto decl init I/O :   2.21 ( 0%) usr   0.03 ( 0%) sys   2.25 ( 0%) wall   82822 kB ( 2%) ggc
 ipa lto cgraph I/O    :   1.85 ( 0%) usr   0.26 ( 1%) sys   2.11 ( 0%) wall  247249 kB ( 7%) ggc
 ipa lto decl merge    :  54.30 ( 7%) usr   1.20 ( 6%) sys  55.63 ( 7%) wall     283 kB ( 0%) ggc
 ipa lto cgraph merge  :   1.35 ( 0%) usr   0.00 ( 0%) sys   1.35 ( 0%) wall    5259 kB ( 0%) ggc
 whopr wpa             :  79.05 (11%) usr   0.14 ( 1%) sys  79.35 (11%) wall   22146 kB ( 1%) ggc
 whopr wpa I/O         :  10.07 ( 1%) usr  12.89 (69%) sys  22.82 ( 3%) wall       0 kB ( 0%) ggc
 ipa reference         :   1.83 ( 0%) usr   0.00 ( 0%) sys   1.79 ( 0%) wall       0 kB ( 0%) ggc
 ipa profile           :   0.19 ( 0%) usr   0.00 ( 0%) sys   0.20 ( 0%) wall       0 kB ( 0%) ggc
 ipa pure const        :   1.44 ( 0%) usr   0.01 ( 0%) sys   1.46 ( 0%) wall       0 kB ( 0%) ggc
 inline heuristics     :  14.37 ( 2%) usr   0.00 ( 0%) sys  14.41 ( 2%) wall    2825 kB ( 0%) ggc
 callgraph verifier    :   9.22 ( 1%) usr   0.19 ( 1%) sys   9.42 ( 1%) wall       0 kB ( 0%) ggc
 varconst              :   0.02 ( 0%) usr   0.03 ( 0%) sys   0.04 ( 0%) wall       0 kB ( 0%) ggc
 TOTAL                 : 732.42            18.73           753.13            3543343 kB

decl out time definitly will reduce with sane partitioning.  Also it seems that osme of my simple
minded partitioning code should be optimized to avoid quadratic behaviour.

Honza