FORTRAN Reference Manual

Compiler Directives
FORTRAN Reference Manual—528615-001
10-24
EXTENDCOMMON Compiler Directive
Example
?ERRORS 250
EXTENDCOMMON Compiler Directive
The EXTENDCOMMON directive instructs the compiler to use indexed indirect
addressing to access simple variables in common blocks in the user data segment.
This method of addressing saves primary global storage but accessing the data in
common blocks is slower than if you do not specify EXTENDCOMMON.
The default value is NOEXTENDCOMMON.
Considerations
•
EXTENDCOMMON has no effect on arrays, simple variables more than two words
in length, or variables in the extended data segment.
•
Normally, FORTRAN allocates one pointer in primary global storage for each entity
in common in secondary global storage. If you specify the EXTENDCOMMON
directive, FORTRAN allocates only one pointer for the first entity in each common
block, one pointer for each array in each common block, and one pointer for all
scalars in each common block. The compiler locates entities that follow by
indexing.
•
Specify the EXTENDCOMMON directive either with the FORTRAN command (after
the semicolon following the object file name) or in the source input file before the
first FORTRAN statement.
•
For additional information, see Section 12, Memory Organization.
Example
?EXTENDCOMMON
EXTENDEDREF Compiler Directive
The EXTENDEDREF directive tells FORTRAN to generate code that uses doubleword
addresses for parameters in CALL statements or function references. Programs that
use extended data space need doubleword addresses to reference data items stored
in extended memory.
The default value is NOEXTENDEDREF, unless you use the LARGECOMMON or
[NO]EXTENDCOMMON