Re: History and evolution of compilers

The moderator wrote:


> Fortran IV did get two compilers on the 360 series, Fortran G which was
> fast and generated rotten code, and Fortran H which produced very good
> code. -John]


As I recall, the Fortran G code wasn't "rotten"; in most cases it was
acceptable (maybe you're thinking about the WATFOR/WATFIV compilers).
Wirth's Algol-W compiler produced code of about Fortran G's quality;
and it ran as fast as the WATFIV compiler.


As to Fortran H, the code was good, but we were warned to check our
results because some of the optimizations could break working code
(how much of this was due to people not adhering to the letter of the
Fortran language spec and how much was due to Fortran-H taking
liberties, I don't know). By the way, the "G" and "H" refer to the
size of machine needed for the compilers; if memory serves me, "G" was
around 128K and "H" was 256K or 512K.


--
Peter Ludemann +1.650.813.6806 (fax: +1.650.813.7400)
Software Architect ludemann@inxight.com
Inxight Software, Inc. http://www.inxight.com
PAHV 118, 3400 Hillview Ave., Palo Alto, CA 94304
[It was acceptable, but it was definitely rotten. For example, it made
no attempt to do base-offset branches, but rather loaded an address word
from memory before every branch. Incidentally, IBM apparently bought
Fortran G from someone else, since DEC's PDP-6/10 Fortran compiler used
the same front end with data structures called "rolls". -John]




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