HP Fortran Programmer Guide (766160-001, March 2014)

NOTE: For libF90, libU77, and libIO77(Itanium® only), archive libraries are selected by
default (see +sharedlibF90, +sharedlibU77, and +sharedlibIO77options).
To force the linker to select archive libraries, specify the -Wl,-a,archiveoption on the
f90command line. f90passes the arguments to the -Wl option (-a and archive) to the linker.
This option must appear before the names of any libraries also specified on the command line.
The following command line compiles prog.f90and links it with the archive versions of the default
libraries as well as with the math library (as specified by the-lm option):
$ f90 -Wl,-a,archive prog.f90 -lm
For information about the linker’s -a option, see the ld(1) man page. For more information about
shared libraries, see “Creating shared libraries” (page 59).
Library search rules
When you use the -loption to specify the name of a library, the linker searches for the library in
the directories specified by the LPATHenvironment variable. The f90command sets this variable
so that the linker looks first in /opt/fortran90/lib, then in/usr/lib . You can specify another
directory to search by settingLPATHyourself; see “LPATH environment variable” (page 65).
Alternatively, you can use the -Ldirectoryoption to direct the linker to search directorybefore
it looks anywhere else to resolve references. For example, the following command line:
$ f90 -L/my_libs prog.f90 -lstuff
causes the linker to search for libraries (including libstuff.sl and libstuff.a), starting
with the directory /my_libsand then looking in /opt/fortran90/lib and /usr/lib.
Special-purpose compilations
The default behavior of the HP Fortran compiler has been designed to handle typical compilations.
Most applications should require no more than a few of the f90options to compile successfully
(see Table on page 25 for a list of commonly used options).
However, the compiler can also meet the needs of more specialized compilations. This section
explains how to use the f90command for the following purposes:
• To compile programs that contain Fortran modules.
• To compile programs that will execute on different PA-RISC machines.
• To create object files for shared libraries.
• To process source files that contain C preprocessor directives.
• To create demand-loadable programs.
• To create shareable executable programs.
• To compile 32-bit programs in 64-bit mode.
Compiling programs with modules
One of the features of standard Fortran is the module, a program unit that facilitates shared access
to data and procedures. Modules are fully described in the HP Fortran Programmer’s Reference.
A benefit to using modules is that they provide interface information to the compiler, allowing it to
catch mismatch errors between (for example) dummy arguments and actual arguments. When the
HP Fortran compiler processes a file that defines a module, it generates a .modfile with the interface
information. Later, when the compiler processes a file that uses the module, it reads the .modfile
and checks that module entities that are referenced in the using file correctly match the information
in the.mod file.
54 Compiling and linking