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Re: Apple's -fast option for gcc
Op wo 17-09-2003, om 19:56 schreef Martin Brain:
> As I understand it the number of levels refers to the scope the
> optimisations work in. -O1 is within basic blocks, -O2 is between basic
> blocks, -O3 is across the entire function. Ofcourse not all
> optimisations can be categorised like this and so have been fitted to
> the nearest appropriate level.
This is not quite true, and certainly not for GCC 3.5 and beyond with
tree-ssa merged. All SSA passes are global, and they're (at present)
all enabled at -O1.