16032 calling sequences

[Brian Thomson]

		    CAST YOUR VOTE TODAY!

You have the opportunity to influence the future of an NS16032 C compiler
developed here at the University of Toronto.  We have not been able to
decide between National's favoured cxp calling sequence and the faster
jsr/bsr.

Our compiler and optimizer are now complete.  Because of our vacillation,
we have parameterized them to generate either calling sequence.  Now it
is time to install libraries and we have to bite the bullet.

We have made some measurements.  

On a sample of 7 common utilities (pstat, ed, tar, ...) we find the
text size of programs using jsr is 5% greater than the optimizing 4.1bsd
VAX compiler produces.  When we recompile using cxp, the cumulative
text size is 5% less than that on the VAX.

We then ran a speed test using the 'dc' calculator utility on
a 5MHz 16032 processor.  One test calculated 10 ** 1000, and there
was no significant speed difference.  A second test, involving no
multiplying but lots of loops and string executions, showed an 8%
speed advantage for jsr.

What do you think, and why?  The issues are:

 1) Speed vs. size, i.e. a technical decision
 
 2) Compatibility.  We understand that National-sponsored
    C implementations are constrained to use cxp, while
    MIT's effort uses jsr.

 3) Whether 1) is more important than 2).

We would be particularly interested in responses from other implementors
especially if you can tell us the reasons for your choice.

				    Brian Thomson,  utcsrgv!thomson
				    David Galloway, utcsrgv!drg
				    CSRG Univ. of Toronto