Suggested addition to documentation

[Joe Buck]

Brad Lucier writes:

> 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.

Do we have enough data to be confident that this is true in general?
Clearly it is true for your applications, and thanks for all the benchmark
studies you ran.  But will it be true for (almost) anyone who uses
computed gotos?