🚀 go-pugleaf

[This consists entirely of "documented ways to run Sun compilers to
get better numbers than plain old -O4."  If you plan to use bizarre
flag combinations for one compiler in a comparison, you ought to make
an effort for the other compiler, unless you already know the answer
that you are looking for.]

In article <1992Feb25.184349.23760@cc.ic.ac.uk> jensting@ee.ic.ac.uk (Jens Tingleff) writes: 
>I tried compiling a large FORTRAN numerical package, using Sun Fortran 1.4, Sun
>CC 1.1 (unbundled) Sun CC and GCC 2.0, computer SStation IPX.
...
>Compiler command lines
>
>1)	Sun bundled	/bin/cc -O4 -c ..
>2)	Sun unbundled	/usr/lang/cc -O4 -c ..
>3)	F77		f77 -O4 -c ..
>4)	GCC 2		gcc -O2 -fstrength-reduce -funroll-loops -c ..

If you're in the mood to mix and match flags and tinker with options,
try using some or all of the following with the Sun compilers:

  -fast 
  -fast -Bstatic
  -fast -O3
  -fast -O3 -Bstatic <-- I recommend this for a first try at speed.
  -fast -O4
  -fast -O4 -Bstatic

I don't know if gcc2 uses dynamic or static binding -- depending upon
the program, it can make a difference.  Most of the official benchmark
numbers quoted for Sun make use of static binding.

"-fast" is a documented convenience option for people who want their
code to run fast.  Suffixing -O3 and -O4 both crank up the
optimization level further.

And yes, the Fortran compiler knows something that f2c+cc do not.
Generally speaking, it knows things that f2c and cc will never know,
unless the C language is changed.  That's one reason people still use
Fortran.

David Chase
Sun