optimization/10160: [3.3/3.4 regression][SPARC] compile time regression; inordinate time spent in "scheduling"

[Vladimir Makarov]

ebotcazou@gcc.gnu.org wrote:
> 
> Synopsis: [3.3/3.4 regression][SPARC] compile time regression; inordinate time spent in "scheduling"
> 
> Responsible-Changed-From-To: vmakarov->ebotcazou
> Responsible-Changed-By: ebotcazou
> Responsible-Changed-When: Wed Apr 16 13:14:39 2003
> Responsible-Changed-Why:
>     Hum... I don't think that the scheduler is to be blamed here,
>     rather the tree inliner: cutting the inlining limit by 10
>     (-finline-limit=60) brings the compile time on par with that
>     of the 3.2.x branch.
> 
>     The new logic of the tree inliner is not exactly adapted to this testcase.
> 
> http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10160

You are absolutely right.  I was afraid that it is because of the first
cycle multipass insn scheduling.  So I switched it off and got the same
result.  So this is not because of the recent insn scheduling changes. 
Simply insn scheduling (even simplest heuristic list one) is O(n*2)
algorithm.  So it may behave very nasty when the input is big.  There
are some heuristics constraining number of dependencies but they do not
help in this case.  Even without insn scheduling compilation of this
file takes 12 minutes on my sparc computer.

Vlad