Re: 50 times longer to compile than copy

smnsn@my-deja.com says...


No comment on the body of the article, but...


>[If your program is one huge routine, I'm not surprised that it takes
>a long time to compile. Compilers almost always have some worse than
>linear time parts that make very large routines very slow. It's not
>likely to be the symbol table, though. If you hash your symbol table,
>which everyone does, acess time is O(1). -John]


The record for this in my experience was the PostScript interpreter at
the heart of James Gosling's NeWS window system. This was a single
routine spread across, as I recall one C file and two header files
(containing executable code!), being two switch statements, one of
which had a case for every operator in the PostScript language. I'm
afraid I can no longer remember how big this routine was in lines or
bytes.


At the time we were compiling on the then new mips r2000, which was 20
times faster than our VAX. After we got NeWS running, we went for an
optimised build. It took 20 hours to compile this single routine.
(We later went from 8Mb of memory on the compile machine to 24Mb, and
the time went down to 40 minutes....) Unoptimised, the compilation
typically took under a minute....


- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Ian Kemmish 18 Durham Close, Biggleswade, Beds SG18 8HZ, UK
ian@jawssytems.com Tel: +44 1767 601 361

Return to the comp.compilers page.
Search the comp.compilers archives again.