XL Fortran Enterprise Edition for AIX : User's Guide - IBM

The invocation commands have the following implications for directive triggers:
v
v
For f77, fort77, f90, f95, xlf, xlf90, and xlf95, the directive trigger is IBM* by
default.
For all other commands, the directive triggers are IBM* and IBMT by default. If
you specify -qsmp, the compiler also recognizes the IBMP, SMP$, and $OMP
trigger constants. If you specify the -qsmp=omp option, the compiler only
recognizes the $OMP trigger constant.
If you specify the -qsmp compiler option, the following occurs:
v The compiler turns on automatic parallelization.
v The compiler recognizes the IBMP, IBMT, IBM*, SMP$, and $OMP directive
triggers.
XL Fortran provides the library libxlf90_r.a, in addition to libxlf90_t.a. The library
libxlf90_r.a is a superset of libxlf90_t.a. The file xlf.cfg is set up to link to
libxlf90_r.a automatically when you use the xlf90_r, xlf90_r7, xlf95_r, xlf95_r7,
xlf_r, and xlf_r7 commands.
libxlf90_t.a is a partial thread-support run-time library. It will be installed as
/usr/lib/libxlf90_t.a with one restriction on its use: because routines in the library
are not thread-reentrant, only one Fortran thread at a time can perform I/O
operations or invoke Fortran intrinsics in a multi-threaded application that uses the
library. To avoid the thread synchronization overhead in libxlf90_r.a, you can use
libxlf90_t.a in multi-threaded applications where there is only one Fortran thread.
When you bind a multi-threaded executable with multiple Fortran threads, to link
in routines in libxlf90_r.a, -lxlf90_r should appear instead of either -lxlf90_t or
-lxlf90 in the command line. Note that using the xlf_r, xlf_r7, xlf90_r, xlf90_r7,
xlf95_r, or xlf95_r7 invocation command ensures the proper linking.
Compiling XL Fortran Version 2 Programs
xlf maintains, wherever possible, compatibility with existing programs by using
the same I/O formats as earlier versions of XL Fortran and some implementation
behavior compatible with FORTRAN 77.
f77 is identical to xlf (assuming that the configuration file has not been
customized).
You may find that you need to continue using these commands for compatibility
with existing makefiles and build environments. However, be aware that programs
that you compile with these commands may not conform to the Fortran 90 or
Fortran 95 standard in subtle ways.
Compiling Fortran 90 or Fortran 95 Programs
The f90, xlf90, xlf90_r, and xlf90_r7 commands make your programs conform more
closely to the Fortran 90 standard than do the xlf, xlf_r, xlf_r7, and f77/fort77
commands. The f95, xlf95, xlf95_r, and xlf95_r7 commands make your programs
conform more closely to the Fortran 95 standard than do the xlf, xlf_r, xlf_r7, and
f77/fort77 commands. f90, xlf90, xlf90_r, xlf90_r7, f95, xlf95, xlf95_r, and xlf95_r7
are the preferred commands for compiling any new programs. They all accept
Fortran 90 free source form by default; to use them for fixed source form, you
must use the -qfixed option. I/O formats are slightly different between these
commands and the other commands. I/O formats also differ between the set of
Editing, Compiling, Linking, and Running XL Fortran Programs 31