-O more than the sum of its parts?

[me22]

On 8 March 2010 22:31, drew stortz <drew.stortz@gmail.com> wrote:
>
> However, experiment tells me that this is far from true.  When I
> compile the same c file both ways, the object file produced with -O is
> around 20% smaller than the one produced with all of the individual
> optimizations added.  Before filing a bug or investigating further, I
> wanted to ask the list: is my interpretation of the -O switch
> incorrect?  Is it more than just the sum of those individual
> optimizations?
>

Yes; My understanding is that all of the -O levels have features not
controllable with individual flags.