Should -fcross-jumping be part of -O1?

[Felix Lee]

kenner@vlsi1.ultra.nyu.edu (Richard Kenner):
> Right now, I count about 20 different optimizations switches and
> 2**20 is significantly larger than 3**5!

but the -f switches are at a different conceptual level than -O
switches.  each -f switch can be tested independently as to
whether they do the thing promised or not.  like -funroll-loops
is a statement that loops will be unrolled, and there's no
promise being made that the result will have any particular
quality other than "loops are unrolled".

the -O switches are statements about more abstract qualities, and
if combinations of them are meaningful, they all should be
checked.  like, "-Ofast=3 -Osmall=2" should not be slower but can
be larger than "-Ofast=2 -Osmall=3", etc.

(checking whether combinations of -f switches produce correct
code is a separate issue, independent of the problem of checking
whether combinations of -O switches are meaningful.)
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