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

s64c
pwr3
pwr4
pwr5
You can run the executable file on any RS64III machine.
You can run the executable file on any POWER3, POWER4, POWER5, or
PowerPC 970 hardware platform. In previous releases, the pwr3 setting
was used to target the POWER3 and POWER4 group of processors. To
have your compilation target a more general processor group, use the
ppc64grsq setting, which includes the POWER3, POWER4, POWER5, or
PowerPC 970 group of processors. Because executable files for these
platforms may contain instructions that are not available on POWER,
POWER2, or other PowerPC systems, they may be incompatible with those
systems.
You can run the executable file on any POWER4, POWER5, or PowerPC
970 hardware platform. Use of -qarch=pwr4 will result in binaries that will
not run on most previous PowerPC implementations.
You can run the executable file on any POWER5 hardware platform.
ppc970
You can run the executable file on any PowerPC 970 hardware platform.
Note: The -qarch setting determines the allowed choices and defaults for the
-qtune setting.You can use -qarch and -qtune to target your program to
particular machines.
If you intend your program to run only on a particular architecture, you can use
the -qarch option to instruct the compiler to generate code specific to that
architecture. This allows the compiler to take advantage of machine-specific
instructions that can improve performance. The -qarch option provides arguments
for you to specify certain chip models; for example, you can specify -qarch=604 to
indicate that your program will be executed on PowerPC 604 hardware platforms.
For a given application program, make sure that you specify the same -qarch
setting when you compile each of its source files. Although the linker and loader
may detect object files that are compiled with incompatible -qarch settings, you
should not rely on it.
You can further enhance the performance of programs intended for specific
machines by using other perfomance-related options like the -qcache and -qhot
options.
Use these guidelines to help you decide whether to use this option:
v
v
v
If your primary concern is to make a program widely distributable, keep the
default (com). If your program is likely to be run on all types of processors
equally often, do not specify any -qarch or -qtune options. The default supports
only the common subset of instructions of all processors.
If you want your program to run on more than one architecture, but to be tuned
to a particular architecture, use a combination of the -qarch and -qtune options.
Make sure that your -qarch setting covers all the processor types you intend
your program to run on. If you run such a program on an unsupported
processor, your program may fail at execution time.
If the program will only be used on a single machine or can be recompiled
before being used on a different machine, specify the applicable -qarch setting.
Doing so might improve performance and is unlikely to increase compile time. If
you specify the p2sc, pwr2, pwr2s, rs64a, rs64b, rs64c, 601, 603, 604, pwr3, pwr4,
pwr5, or ppc970 suboption, you do not need to specify a separate -qtune option.
XL Fortran Compiler-Option Reference 129