phr@mit-hermes.UUCP (02/19/87)
I just ran the notorious Dhrystone benchmark through the GNU C compiler and compared the results with the Unix compiler. They generally favor GCC. Recent discussion on comp.arch suggests that Dhrystone is not a wonderful measurement of either CPU or compiler performance, but it's better than nothing; don't treat these numbers as if they were holy. The first four runs were with 50000 Dhrystone passes; the last two were with 500000. The 500000 pass test was time consuming so I only ran it with optimizers on (the interesting case). Each of the first four tests were run twice in succession to get things into cache, and the SECOND timing is given in each case. The last two tests were run only once each. All measurements were taken on an unloaded diskless Sun 3/75 workstation with 8 megabytes of memory running Sun 4.2bsd Unix. I don't know the exact release numbers of the Sun OS or compiler. Times are in seconds, sizes in bytes. Compile times are user time followed by system time. Compiler Compile time Code size Run time Dhrystones/sec GCC, opt off 3.6u/1.8s 1888 18.5 2707 Sun cc, opt off 3.9u/1.4s 1812 16.4 3061 Sun cc -O 5.5u/1.8s 1576 15.0 3363 GCC -O 4.0u/1.4s 1348 12.6 4005 Sun cc -O (as above) 149.3 3368 GCC -O (as above) 125.4 4012 Remarks: 1. GCC will go into beta test pretty soon now; we'll make an announcement when that happens. Please don't flood us with mail yet. It will eventually be distributed free, like GNU Emacs. (Hats off to RMS for this winning new compiler). 2. Code from GCC without -O runs slow because some optimizations are deliberately not done in order to improve debuggability of the object code. However, you can still use gdb or dbx on gcc -O output, with some success. 3. Dhrystone.c is probably not large enough for the code size numbers in this test to be meaningful, but generally gcc -O output is several percent smaller than cc -O output. 4. I hope to try the benchmark on the Vax pretty soon.
root@sdd.UUCP (02/26/87)
What CPUs / architectures / a.out formats is the GNU C compiler work for? How easy will it be to port the compiler to other machines / CPUs? Is gbd the GNU equivalent to sdb? If so, is it currently available. I would like to have a debugger that works with C++. Daniel Corbett Software Design & Development Corp Camarillo, CA 93010 UUCP: ihnp4!nrcvax!sdd!root