Technical data

8
Chapter 1: Compiling, Linking, and Running Programs
Driver Options
This section contains a summary of the Fortran–specific driver options. See
the f77(1) manual page for a complete description of the compiler options;
see the ld(1) manual page for a description of the link editor options.
–66 Compiles Fortran 66 source programs.
When used at compile time, the following four options generate various
degrees of misaligned data in common blocks. They then generate the code
to deal with the misalignment.
Note: When specified, these options can degrade program performance;
–align8 causes the greatest degree of degradation, and –align32 causes the
least.
–align8 Aligns objects larger than 8 bits on 8-bit boundaries. Using
this option will have the largest impact on performance.
–align16 Aligns objects larger than 16 bits on 16-bit boundaries;
16-bit objects must still be aligned on 16-bit boundaries
(MC68000-like alignment rules).
–align32 Aligns objects larger than 32 bits on 32-bit boundaries;
16-bit objects must still be aligned on 16-bit boundaries, and
32-bit objects must still be aligned on 32-bit boundaries.
–align64 Aligns objects larger than 64 bits on 64 bit boundaries.
Objects with size 64 bits or smaller must still be aligned on
the corresponding boundaries.
The current default alignment is 32 bits. This number may
be changed in the future to take advantage of the new 64-bit
architecture.
You must specify the appropriate alignment option in the
compilation of all modules that reference or define common
blocks with misaligned data. Failure to do so could cause
core dumps (if the trap handler is not used) or mismatched
common blocks.