[Bug target/67396] [4.9/5.0 regression] Performance regression compiling variadic function with many arguments

[ppluzhnikov at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67396

--- Comment #3 from Paul Pluzhnikov <ppluzhnikov at google dot com> ---
(In reply to Andrew Pinski from comment #2)

> Can you provide -ftime-report ?

Sure:

perl gen_bz18872.pl 2000 > t.c && gcc-svn-r227321/bin/gcc -c -O2 t.c
-ftime-report

Execution times (seconds)
 phase setup             :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.00 ( 0%) wall 
  1066 kB (19%) ggc
 phase parsing           :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.02 ( 0%) wall 
  1486 kB (27%) ggc
 phase opt and generate  : 102.09 (100%) usr   0.01 (100%) sys 102.29 (100%)
wall    2997 kB (54%) ggc
 garbage collection      :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 CFG verifier            :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 df use-def / def-use chains:   0.01 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%)
wall       0 kB ( 0%) ggc
 preprocessing           :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
   948 kB (17%) ggc
 lexical analysis        :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 parser (global)         :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.00 ( 0%) wall 
   297 kB ( 5%) ggc
 tree STMT verifier      :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 dominance computation   :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 expand                  :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
   484 kB ( 9%) ggc
 dead store elim1        : 101.85 (100%) usr   0.01 (100%) sys 101.96 (100%)
wall     171 kB ( 3%) ggc
 dead store elim2        :   0.11 ( 0%) usr   0.00 ( 0%) sys   0.11 ( 0%) wall 
   171 kB ( 3%) ggc
 CSE 2                   :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 integrated RA           :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
    24 kB ( 0%) ggc
 reload CSE regs         :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
   280 kB ( 5%) ggc
 thread pro- & epilogue  :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.02 ( 0%) wall 
     1 kB ( 0%) ggc
 peephole 2              :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 scheduling 2            :   0.06 ( 0%) usr   0.00 ( 0%) sys   0.08 ( 0%) wall 
  1558 kB (28%) ggc
 initialize rtl          :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.00 ( 0%) wall 
    12 kB ( 0%) ggc
 rest of compilation     :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.02 ( 0%) wall 
     2 kB ( 0%) ggc
 unaccounted todo        :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.00 ( 0%) wall 
     0 kB ( 0%) ggc
 verify RTL sharing      :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.00 ( 0%) wall 
     0 kB ( 0%) ggc
 TOTAL                 : 102.10             0.01           102.31              
5558 kB
Extra diagnostic checks enabled; compiler may run slowly.
Configure with --enable-checking=release to disable checks.


perf report says:

Samples: 409K of event 'cycles', Event count (approx.): 374080784459
 32.25%  cc1  cc1                [.] find_base_term(rtx_def*)
 27.15%  cc1  cc1                [.] get_addr(rtx_def*) [clone .part.39]
 16.57%  cc1  cc1                [.] rtx_equal_for_memref_p(rtx_def const*,
rtx_def const*)
 11.37%  cc1  cc1                [.] memrefs_conflict_p(int, rtx_def*, int,
rtx_def*, long) [clone .constprop.113]
  5.76%  cc1  cc1                [.] addr_side_effect_eval(rtx_def*, int, int)
[clone .constprop.114]
  2.81%  cc1  cc1                [.] ix86_find_base_term(rtx_def*)
  2.52%  cc1  cc1                [.] cselib_sp_based_value_p(cselib_val*)
  1.11%  cc1  cc1                [.] cselib_have_permanent_equivalences()
  0.13%  cc1  cc1                [.] record_store(rtx_def*, dse_bb_info_type*)
...