[gambit-list] Poor compilation of do-loops

Bradley Lucier lucier at math.purdue.edu
Sat Oct 17 19:45:14 EDT 2009

If matrix-ref is inlined into the calculation

				  (fl+ a
				       (fl* (matrix-ref m1 i k)
					    (matrix-ref m2 k j))))))))))))))

then there is even greater speedup, partly because no flonums need to be
boxed as return values of matrix-ref.  The compiler inlines some uses,
but I tried to inline all uses with inlining-limit, but failed (bug 117,
I think), but after writing matrix-ref and matrix-set! as macros, I get
the following runtimes (on a different machine than before).

Original code (but compiled using gsc -exe, so twice as fast as original
report, "with all possible optimizations turned on"):
    1344 ms cpu time (1340 user, 4 system)
Using declarations, fixnum- and flonum-specific operations, and
    784 ms cpu time (776 user, 8 system)
Using named let:
    336 ms cpu time (328 user, 8 system)
Inlining all (not just some) instances of matrix-ref and matrix-set!:
    124 ms cpu time (120 user, 4 system)

I'm planning to use Gambit again in my numerical PDE class next
semester, so I'd like to win these benchmark games ;-).


On Thu, 2009-10-15 at 12:22 -0400, Bradley Lucier wrote:
> Marc:
> At the end of this message I suggest a compiler transformation of
> do-loops that doubles the speed of the sample code.
> A matrix multiplication benchmark recently was posted to the Chicken
> list, see the thread beginning here:
> http://lists.gnu.org/archive/html/chicken-users/2009-10/msg00050.html
> The Gambit version of the benchmark has no Gambit-specific declarations,
> uses generic vectors and arithmetic.

More information about the Gambit-list mailing list