Language Reference

Components of the XL Fortran Language

XL Fortran Version 6.1 provides the following features:

• The full function of XL Fortran Version 5.1.1
• Support for the full Fortran 95 standard, including the following items, which are new in Version 6.1:

  • Default initialization of derived type components

  • User-defined elemental procedures

  • Specification functions in specification_expressions

  • NULL intrinsic function

  • Namelist comments

  • Automatic deallocation of allocatable arrays

  • SIGN intrinsic function support for -0.0

  • Zero-width support for I, B, O, Z, and F edit descriptors

  • WHERE statements and WHERE construct statements nested within WHERE constructs

  • Masked ELSEWHERE statements

  • Named WHERE constructs

  • generic_spec on END INTERFACE

  • :: for EXTERNAL and INTRINSIC keywords

  • -qlanglvl compiler option flagging of items not compliant with the Fortran 95 standard.

  • LANGLVL run-time option flagging of items not compliant with the Fortran 95 standard.

  • KIND argument for the CEILING and FLOOR intrinsic functions

  • Use of module procedure statements anywhere in generic interface blocks

  • Subobject of a constant as a DATA statement repeat count

  • Support for the MASK argument as the second argument in references to the MAXVAL, MINVAL, PRODUCT, and SUM intrinsic functions, without the MASK= argument keyword, when the DIM argument is not present

  • Use of almost any intrinsic function in specification_expressions

  • Printing of the minus sign for negative zero in formatted output and for negative values that have an outputted form of zero

  • -qxlf90 compiler option, to provide backward compatibility with Fortran 90 for certain cases
• Support for the following features of the OpenMP Fortran API:

  • PARALLEL region construct

  • DO/END DO directives and DO (work-sharing) construct

  • MASTER/END MASTER directives and MASTER construct

  • DEFAULT clause in directives

  • FIRSTPRIVATE clause in directives

  • BARRIER directive

  • END PARALLEL DO directive

  • omp_get_thread_num service and utility procedure

  • omp suboption for the -qsmp compiler option.
• Support for the following other items:

  • xlf95, xlf95_r, and xlf95_r7 invocation commands

  • -qdpcl compiler option, to generate information for the Dynamic Probe CLASS Library API

  • New suboptions for the -qtune and -qarch compiler options, to support the POWER3 and RS64II processors

  • -qinitauto compiler option support for automatic objects

  • Updated LPEX editor and Program Builder tools

  • Passing of the -I option to cpp

Invocation Commands

There are ten invocation commands for the XLF Version 6.1 compiler: f77, xlf, xlf_r, xlf_r7,xlf90, xlf90_r, xlf90_r7, xlf95, xlf95_r, and xlf95_r7. The latter three invocation commands are new for the XLF Version 6.1 compiler:

The following table summarizes the invocation commands that you can use:

Table 1. XL Fortran Version 6.1 Invocation Commands

Driver Invocation	Path or Location	Chief Functionality	Linked Libraries
xlf90	/usr/bin	Fortran 90	libxlf90.a
xlf90_r	/usr/bin	Threadsafe Fortran 90, operating system default POSIX pthreads API	libxlf90_r.a
xlf90_r7	/usr/bin	Threadsafe Fortran 90, Draft 7 POSIX pthreads API	libxlf90_r.a
xlf95	/usr/bin	Fortran 95	libxlf90.a
xlf95_r	/usr/bin	Threadsafe Fortran 95, operating system default POSIX pthreads API	libxlf90_r.a
xlf95_r7	/usr/bin	Threadsafe Fortran 95, Draft 7 POSIX pthreads API	libxlf90_r.a
xlf	/usr/bin	FORTRAN 77	libxlf90.a
xlf_r	/usr/bin	Threadsafe FORTRAN 77, operating system default POSIX pthreads API	libxlf90_r.a
xlf_r7	/usr/bin	Threadsafe FORTRAN 77, Draft 7 POSIX pthreads API	libxlf90_r.a
f77	/usr/bin	FORTRAN 77	libxlf90.a

The invocation commands have the following implications for directive triggers:

• For f77, xlf, xlf90, and xlf95, the directive trigger is IBM* by default.

• For all other commands, the directive triggers are IBM* and IBMT by default. If you specify the -qsmp=omp option, the compiler only recognizes the $OMP trigger constant. If you specify the -qsmp=noomp option, the compiler also recognizes the IBMP, SMP$, and $OMP trigger constants.

If you specify the -qsmp compiler option, the following occurs:

• The compiler turns on automatic parallelization.
• The program will recognize all SMP directives.

For more information, see "Compiling XL Fortran Programs" in the User's Guide for XL Fortran for AIX.