1. XLF 9.1 Ian J. Bush Computational Science and Engineering Department CCLRC Daresbury Laboratory Warrington WA4 4AD I.J.Bush@dl.ac.uk

2. 22 nd June 2005ScicomP-11 XLF 9.1 Currently available as a non-default install (NDI) –See the HPCx mailing on 15 th July for how to use it The intention is to make it the default on 28 th of September –If no major problems are reported –It’s up to YOU to test it on your code !

3. 32 nd June 2005ScicomP-11 Why XLF 9.1 Extra compiler facilities Extra language facilities –Partial support for Fortran 2003 Performance

4. 42 nd June 2005ScicomP-11 New Compiler Facilities -qflttrap=nanq –Detect all NaN values –Help debugging -qsaveopt –Saves the compiler options in the object file –Now quite what did this get compiled with… -qversion –At long last !!! More directives to help optimisation MASS now supported (by the compiler group) Power5 ( and cell ) support

5. 52 nd June 2005ScicomP-11 Language Facilities Full OpenMP 2.0 support Partial support for Fortran 2003 –C Interoperability –Mixed Public and Private entities in a derived type –Access to command line and environment –Information about the implementation –Flush statement –IOMSG= specifier in I/O statements –Various others: ASSOCIATE, IMPORT, PROCEDURE, NEW_LINE Full support in xlf 11 (xlf 10 next year)

6. 62 nd June 2005ScicomP-11 C Interoperability Provides a portable way of mixing Fortran and C in the same code –Uses Fortran kinds to map between C data types and Fortran Mapping comes from an intrinsic module –Facilities to convert between Fortran and C pointers

7. 72 nd June 2005ScicomP-11 C Interoperability Fortran Side Interface Subroutine hostname( host, length, error ) Bind( c ) Use, Intrinsic :: iso_c_binding Character( Kind = c_char ), Dimension( * ) :: host Integer( c_int ), Value :: length Integer( c_int ) :: error End Subroutine hostname End Interface.. Call hostname( host, length, error ) C Side void hostname( char *host, int length, int *error ){ *error = gethostname( host, length ); }

8. 82 nd June 2005ScicomP-11 Access to the Command Line command_argument_count() –Intrinsic function that returns the number of arguments to the command Call get_command_argument(... ) –Access to each of the command arguments Call get_command(... ) –Access the complete command line Methods for error checking provided – e.g. did you provide a big enough buffer ?

9. 92 nd June 2005ScicomP-11 Information About the Implementation All Fortran implementations have certain aspects that are specific to the environment. The intrinsic module iso_fortran_env contains values to help programs avoid depending on specific values. E.g. input_unit, output_unit, error_unit –Which units are preconnected to stdin, stdout, stderr numeric_storage_size, character_storage_size –The size, in bits, of storage units iostat_end, iostat_eor –The values returned by IOSTAT= for EOF and EOR

10. 102 nd June 2005ScicomP-11 Other Facilities There is now a FLUSH statement. –Similar syntax to close, rewind etc. When an I/O error occurs by use of the IOMSG= specifier you can get an error message from the implementation describing what has occurred

11. 112 nd June 2005ScicomP-11 Performance - SpecFP

12. 122 nd June 2005ScicomP-11 Performance – Apps on HPCx PCHAN –DNS CFD code – on average 1.44 times faster under xlf9.1 Centori –Tokamak simulation code –1.22 times faster under xlf9.1 CASTEP –Ab initio electronic structure code –1.06 times faster under xlf9.1 No app found to be slower under xlf9.1

13. 132 nd June 2005ScicomP-11 PCHAN – Compiler Comparison

14. 142 nd June 2005ScicomP-11 Summary And Further Info xlf9.1 –Improved flags and directives –MASS now supported –Partial F2003 support –Improved performance xlf10 out next year Full information on IBM Fortran compilers at http://publib.boulder.ibm.com/infocenter/comphelp/index.jsp