Remove unnecesary line number notes

Jan Hubicka jh@suse.cz
Fri Nov 10 16:45:00 GMT 2006


> I believe the cfglayout.c hunk brought us a ~10% compile-time hit for 
> c++bench
> (introduced between revs 118648 and 118650).  Maybe you are missing a
> continue; after it and check_block_change on that insn get's us slow?

Well, the patch was supposed to do the exact oposite :) (tramp3d is
especially interesting testcase as it tends to produce several line
number notes for each instruction).
I think the code should be OK as it is - check_block is very cheap and
should work on deleted instruction and rest of the chunk is skipped as
notes are not active (not sure why the check_block call is not guarded
too).

I guess what might happen is that number of RTL optimizers works on
window of fixed number of instructions and skipping notes might be
cheaper than processing real instruction, but all that is just if you
compile with -g that I would not expect.  Without that the patch should
really be NOP...

I guess you don't have -ftime-report output handy?

Honza
> 
> Richard.



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