tiny df_note speedup

[Jeff Law]

On 06/02/10 19:50, Jan Hubicka wrote:
> Hi,
> Another thing I noticed is that df_note_* code shows quite top in the
> profiles.  This patch micro optimize two quite obvious things I noticed
> while glancing over the code.
> One thing I do not understand is all the logic about removing REG notes
> and adding them back.
> We already manage freelist for notes so just removing them to freelist
> and constructing again should be fine and actually faster since the
> code is trying to match old ones for no apparent reason?
>
> Bootstrapped/regtested x86_64-linux, OK?
> Honza
>
> 	* df-problems.c (df_create_unused_note, df_note_bb_compute):
> 	micro-optimize the checks when to add new note.
>    
OK.
Jeff