CLANG vs GCC tests of fortran/f2c program

Wojciech Puchar wojtek at wojtek.tensor.gdynia.pl
Wed Jun 20 04:26:21 UTC 2012


i tested your test program, and in that case, contrary to testing common 
unix programs, difference is far higher showing gcc superiority.

i did this test with FreeBSD 9 supplied clang and FreeBSD 9 supplied gcc.

clearly shows that clang actually cannot do more agressive optimization 
(that trades space) at all, and at -O2 is far slower.




produced:

-rwxr-xr-x  1 tmp  tmp  11168 20 cze 06:18 test.cc.O2
-rwxr-xr-x  1 tmp  tmp  17024 20 cze 06:18 test.cc.O3
-rwxr-xr-x  1 tmp  tmp  17024 20 cze 06:18 test.cc.O9
-rwxr-xr-x  1 tmp  tmp  11096 20 cze 06:18 test.clang.O2
-rwxr-xr-x  1 tmp  tmp  11096 20 cze 06:18 test.clang.O3


cc.O2:


real    0m2.877s
user    0m2.829s
sys     0m0.030s

cc.O3:

real    0m2.142s
user    0m2.131s
sys     0m0.000s


cc.09:

real    0m2.071s
user    0m2.054s
sys     0m0.008s


clang.O2:

real    0m3.440s
user    0m3.405s
sys     0m0.018s

clang.O3:

real    0m3.217s
user    0m3.205s
sys     0m0.001s




How about leaving politics and getting back to technical grounds?

>From what i know now GPLv3 isn't really a problem for us, your may freely 
distribute binary only software compiled by latest gcc.


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