Re: Sun Studio Express 3 compilers available for download

In article <uRbnh.329175$Fi1.45780@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
*** Hendrickson <***.hendrickson@xxxxxxx> wrote:

1) In production codes, essentially all array operations are performed
in subroutines on arrays with passed in dimensions. The compiler has
no size information to help it decide what to do.

This is true, however, inlining, interprocedural analysis, and
constant propagation can often discover useful info. And F77 codes are
generally better than F9X codes: that straight-jacket that makes
dynamic sizes hard leads to better code.

In the unknown size case, some compilers generate multiple versions of
loops for different sizes, but it's easy to end up with a lot of code
bloat doing this.

3.5) Maybe the compiler can prove that J:K,L:M runs over the entire
array, in which case it can use a single equivalent DO loop with no
need to worry about loop order.

This optimization was very useful on vector machines, and today it
sometimes improves SIMDization.

-- greg
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