7.3 Porting From Scientific Mainframes

If the application code was originally developed for 64-bit (or 60-bit) mainframes such as CRAY or CDC, you might want to compile these codes with the following options when porting to an UltraSPARC platform, for example:

-fast -m64 -xtypemap=real:64,double:64,integer:64

These options automatically promote all default REAL variables and constants to REAL*8, and COMPLEX to COMPLEX*16. Only undeclared variables or variables declared as simply REAL or COMPLEX are promoted; variables declared explicitly (for example, REAL*4) are not promoted. All single-precision REAL constants are also promoted to REAL*8. (Set -xarch and -xchip appropriately for the target platform.) To also promote default DOUBLE PRECISION data to REAL*16, change the double:64 to double:128 in the -xtypemap example.

See the Fortran User’s Guide or the f95(1) man page for details.