So far, under Linux the compiler of the
Portland Group
usually has been used to compile COBOLD.
The compiler is called with pgf90.
Important switches are:
-byteswapio: With this flag set, binary files in
  big_endian format
  (the standard for UIO files)
  are automatically transformed to
  little_endian
  and vice versa.
-fast: General optimization flag to choose (close to)
  optimum optimization for local machine.
-Mvect=sse: Optimization: Allow Pentium III vector commands.
-Mcache_align: Optimization: Align some data object
  on cache-line boundaries.
-Minline=...: Optimization: Routines that should be
  inlined: 
rhd_hyd_module.F90: rhd_hyd_avg,
  rhd_hyd_upwind,
  rhd_hyd_pred0,
  rhd_hyd_predm,
  rhd_hyd_predp,
  rhd_hyd_alpha,
  rhd_hyd_constanteq,
  rhd_hyd_minmodeq,
  rhd_hyd_minmod,
  rhd_hyd_vanleereq,
  rhd_hyd_vanleer,
  rhd_hyd_superbeeeq,
  rhd_hyd_superbee,
  rhd_hyd_ppeq,
  rhd_hyd_pp,
  rhd_hyd_hdflux, 
rhd_lhdrad_module.F90:
  rhd_rad3d_raylhd,
  rhd_rad3d_solve,
  rhd_rad3d_solveeq, 
rhd_shortrad_module.F90:
  rhd_shortrad_operator.
-DMSrad_raytas1=1: Optimization: choose non-default version
  of SUBROUTINE raytas in file MSrad3D.F90.
-Drhd_shortrad_operator_l01=1: Optimization: version of operator
  for short characteristics method