Re: Suggested addition to documentation

[Brad Lucier <lucier at math dot purdue dot edu>]

> > I couldn't find the best place in the documentation to put this note.
> > 
> > This is true for 3.0; I believe there have been three questions
> > about this performance issue since last summer posted to the
> > gcc mail list.
> > 
> > Note: If you write a program using computed gotos, a GCC extension,
> > and you compile the program with optimization level @samp{-O2} or higher,
> > you may get better runtime performance if you disable the global common
> > subexpression elmination (gcse) pass by adding the @samp{-fno-gcse} option'
> > to the command line.
> 
> I suggest to put it in invoke.texi, in the description of the -fgcse option.

OK, but I'm not putting it anywhere, since I don't have check-in
privileges.

Also, gcse is invoked by default with -O2, and I'm not
sure that users with performance problems with programs compiled with
-O2 are going to go through the list of all optimizations activated by
-O2 to see if there are any caveats associated with any of them.

Brad