Using Fortran directives | HP UX Fortran Software manual

NOTE: Using this directive to incorrectly assert that a routine has no side effects can result in wrong answers when a call to the routine is embedded in a loop.

Cray's implementation of this directive requires that it precede any executable statement or statement function. HP Fortran does not enforce this requirement.

130 Using Fortran directives

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HP UX Fortran Software manual Using Fortran directives

Contents

HP Fortran Programmer Guide AbstractPage Contents Debugging Using the on statementControlling data storage Performance and optimization Calling C routines from HP Fortran 110 Using Fortran directives 123Writing HP-UX applications 107 Migrating to HP Fortran 131 Porting to HP Fortran 141 Fortran 2003 Features 151Documentation Feedback 153 Glossary 154 Index 159 HP secure development lifecycle HP Fortran compiler environment An overview of HP FortranAn overview of HP Fortran +dryrun DriverOptions for controlling the f90 driver +preinclude= file Preprocessor Options for controlling the C preprocessor Front-end Options for controlling the front end +moddir=directory Back-end Options for controlling optimization Optimization Options for controlling code generation+Onooptimization +DAmodel Linker Options for controlling the Linker Ldirectory +FPflagsOoutfile HP-UX operating system ToolsWl ,options Compiling and linking Compiling with the f90 commandF90 command syntax $ f90 hello.f90 Command-line options Command-line optionsF90 command syntax Example 2 hello.f90 Commonly-used options Command-line options by categoryCommonly-used options +save Option descriptions Options listed by category Do I+1, N Example 3 Example+allowunaligned +autodbl +autodbl4 Data type sizes and +autodbl414164 Boption +check=bounds +cpp=default+charlit77 +nocfc +DDdatamodel Name=def+DAmodel Datamodelare Itanium2 BlendedItanium Native Values for the +FP option Gformat77 Signals recognized by the +fpexception option+hugecommon Example 4 % f90 +hugecommon=results pcvals.f90 +initheapcomplex=rvalival /usr/include directory +noimplicitnone+indirectcommonlist=file +initheapinteger=ival +nocheckuf +io77Ipo +nolibs With different values of optlevel Levels of optimizationRequires concurrent use of the +Oprofile=use option +noobjdebug +pa1 +r8 +demandload option. The default is +nodemandload+nodemandload the default +realconstant=single F90com Tx,pathTp,/usr/ccs/lbin/cpp End.o Wx,arg1,arg2,...,argN Bextern =symbol ,symbol Symbol binding optionsBdefault=symbol,symbol Bhidden =symbol ,symbol Reviewing general optimization options Using optimization optionsF90 +O3 +Osize myprog.f90 +Onoautopar +Oconservative+Onoall +Oautopar and omit +Oparallel Fine-tuning optimization options F90 +O3 +Onomoveflops +Ofltacc myprog.f90 +Ocachepadcommon option Default is +OnocxlimitedrangeDefault is +Odataprefetch +Onocxlimitedrange +Onoentrysched +Onofenvaccess+Onofastaccess +Onofailsafe Optimizations performed by +Onofltacc +Onoinlinefilename +Oinlinebudget=n +Oinlinebudget enables+Onoinline +Onoinline=function1,function2 Values for the +Oinlinebudget option Millicode versions of intrinsic functions +Oloopunroll=4 +inlinelevel num+Onoloopunroll=factor +Onoloopunrolljam +Onoparmsoverlap Default is+Onoparmsoverlap+Oparallelintrinsics +Onopipeline Default is +Oshortdata=8 Default is +Onopromoteindirectcalls+Onorecovery For +Oprofile=collectarc,stride Filenames Filenames recognized by f90 Linking HP Fortran programs Linking with f90 vs. ld Linking to libraries Libraries linked by default on PA-RISCLibraries linked by default on Itanium $ f90 -c hello.f90 # compile Linking to nondefault libraries Linking HP Fortran 90 routines Linking to shared libraries Additional HP Fortran librariesOpt/fortran90/lib/pa2064/ -lF90 -lisamstub Library search rules Special-purpose compilationsCompiling programs with modules $ f90 -Wl,-a,archive prog.f90 -lm Special-purpose compilations Example 6 Example 2-2 main.f90 ExamplesExample Example 7 Example 2-3 code.f90 $ f90 -o dostats data.f90 code.f90 main.f90 Compiling with makeExample 8 Example 2-4 data.f90 $ dostats Example 9 Example 2-5 makefile Compiling for different PA-RISC machinesManaging .mod files $ make Creating shared libraries Compiling with +pic Using the C preprocessor Linking with -b Example 13 Example 2-9 cppdirect.f90 Using the C preprocessorProcessing cpp directives $ f90 +cpp=yes -D Debug cppdirect.f90 Creating shared executables Creating demand-loadable executablesSaving the cpp output file $ f90 +noshared prog.f90 Compiling in 64-bit modeUsing environment variables HP Fortran environment variables HPF90OPTS environment variable F90ROOT environment variableSTF90COM64 environment variable $ f90 +list hello.f90 Lpath environment variable Floating installationFloating installation Mpnumberofthreads environment variable Setting up floating installation Alternate-path/opt/fortran90.3.6.1 Automatic and static variables Controlling data storageDisabling implicit typing Disabling implicit typing Contains Controlling data storage Increasing the precision of constants Increasing default data sizes Increasing default data sizes Increasing default data sizes Usr/lib/libpthread.sl Sharing data among programsWhich creates multiple threads $ gotosleep Sharing data among programs $ wakeup Modules vs. common blocksIm up Modules vs. common blocks Debugging Using the HP WDB debuggerStripping debugging information Handling runtime exceptions Signals recognized by +fpexceptionSignal Floating-point exceptions Floating-point exceptions Bus error exception= 1.0/0.0 Illegal instruction exception Segmentation violation exception Using debugging lines Bad argument exception On REAL8 DIV 0 Call divzerotrap Using the on statementExceptions handled by the on statement Exceptions handled by the on statement On Double Precision DIV 0 Call divzerotrap Actions specified by onExceptions handled by the on statement Example 14 Example5-1 abort.f90 Ignoring errorsTerminating program execution Example 15 Example5-2 ignore.f90 Trapping integer overflow exceptions Calling a trap procedureTrapping floating-point exceptions On Double Precision Overflow Call trap Allowing core dumps Trapping +Ctrl-C trap interruptsExample 17 Example5-4 callitrap.f90 Example 18 Example 5-5 allowcore.f90 On Real Overflow Ignore Performance and optimization Using profilersUsing profilers HP Caliper Program.c Comparing Program PerformanceOpt/ansic/bin/cc -Aa +O3 -o program +Oprofile=collect Programprogramarguments Specifying PBO file names and locations Using Options to Control Data CollectionGprof $ gprof prog gprof.out Prof Using options to control optimizationUsing +O to set optimization levels $ f90 +O4 file.f90 +O3 Using the optimization options+O2, -O +O4 $ f90 +O4 +Oaggressive +Ofltacc prog.f90 Fine-tuning optimization options$ f90 +02 +Oaggressive +Osize prog.f90 Packaged optimization options +O2 Is +Onofastaccess at+Ofastaccess at level +Ofltacc=relaxed Fast +Ofltacc=relaxed . This+Onoinitcheck +Olibcalls +Oinlinelevel num+Onolibcalls +Onoloopunroll=n +Onoparminit +Opipeline +Orecovery +Oshortdata=8 +Oregreassoc+Onoreturn +Ovectorize option on +Onowholeprogrammode Conservative vs. aggressive optimization+Owholeprogrammode Compiling for parallel execution Conservative, aggressive, and default optimizationsParallelizing HP Fortran programs F90 +O3 +Oparallel -c x.f90 y.f90 F90 +O3 -c z.f90 Conditions inhibiting loop parallelization Performance and parallelizationProfiling parallelized programs Calling routines with side effects parallellization Indeterminate iteration counts Data dependences F90 +O3 +Ovectorize prog.f90 Using the +Ovectorize optionVectorization Vector routines called by +Ovectorize Sdot Controlling vectorization locallySaxpy Vecdmultadd REAL, External sdot Calling Blas library routinesExample 19 Example 6-1 axpy.f90 Industry-wide standard Vectorization Controlling code generation for performance $ fprog arg1 another arg Accessing command-line argumentsWriting HP-UX applications Example 20 Example 7-1 getargs.f90 Performing I/O using HP-UX system calls Using HP-UX file I/OStream I/O using Fstream Calling HP-UX system and library routines Using HP-UX file I/O Obtaining an HP-UX file descriptor Data types Calling C routines from HP FortranData type correspondence for HP Fortran and C Size differences between HP Fortran and C data types Unsigned integersLogicals Size differences after compiling with +autodbl Complex sqrcomplexCOMPLEX cmxval Complex numbersExample 21 Example 8-1 passcomplex.f90 Pointers Argument-passing conventionsDerived types Example 22 Example 8-2 sqrcomplex.c Void fooint *ptr, int iarray100, int Integer ptr INTEGER, DIMENSION100 iarrayCase sensitivity Call foo%REFptr, %REFiarray, %VALi Example 24 Example 8-4 testsort.f90 Example 23 Example 8-3 sortem.c$HP$ Alias bubblesort = BubbleSort%REF,%VAL Case sensitivity Arrays Memory layout of a two-dimensional array in Fortran and CREAL, DIMENSION2,3,4 Int Example 25 Example 8-5 passarray.f90 Example 26 Example 8-6 getarray.c Fortran hidden length argument StringsNull-terminated string Passing a string Following are example C and Fortran programs Strings Example 27 Example 8-7 passchars.f90 File handlingExample 28 Example 8-8 getstring.c Example 29 Example 8-9 fnumtest.f90 File handling Extern int somedata Sharing dataInt somedata Extern int globals100 Directive syntax Using Fortran directivesUsing HP Fortran directives HP Fortran directives $HP$ Alias name = external-name arg-pass-mode-list SyntaxDescription and restrictions Name Case sensitivity Local and global usageArgument-passing conventions Example 31 Example 9-1 prstr.c StringsFor more information Example 32 Example 9-2 passstr.f90 Example 33 Example Disables the inclusion of source lines in the listing fileSpecified on the command line Listing file Compatibility directives recognized by HP Fortran Compatibility directivesControlling vectorization Vendor Directive Cray Controlling checks for side effects Controlling parallelizationControlling dependence checks Compatibility directives Using Fortran directives Incompatibilities with HP Fortran Command-line options not supportedMigrating to HP Fortran Compiler limits Intrinsic functions Format field widthsFloating-point constants Double Precision x = Procedure calls and definitions Data types and constants Foo**REALbar, 8 ! foo**bar Input/outputDirectives KEY= Migration issues Migration issuesSource code issues Miscellaneous Directives HP Fortran 77 directives supported by f90 options Conflicting intrinsics and libU77 routine names Command-line option issuesIntrinsic functions F77 options supported by f90 Object code issues Data file issues Approaches to migration HP-supplied migration tools $ fid +800 file.f $ fid +es program.f Compatibility statements Porting to HP FortranCompatibility extensions END structure definition Pointer Cray-style Compiler directivesCompatibility directives +Oparallel or Directive prefixes recognized by HP Fortran Intrinsic proceduresNonstandard intrinsic procedures in HP Fortran +Oparallel or +Ovectorize Using porting options Uninitialized variables One-trip do loops Using porting optionsLarge word size $ f90 testloop.f90 Example 34 Example 11-1 clash.f90 Name conflictsExternal int1 Names with appended underscores Source formats Escape sequences Porting from Tru64 to HP Fortran+cfc Nof66alternate for +noonetrip EnhancementsNew options Porting from Tru64 to HP Fortran Check noboundsoptions for example, -nocheckbounds +nopadsrc Altparam Input/output enhancements Fortran 2003 FeaturesInteroperability with C Miscellaneous enhancements Fortran 2003 Features Object orientation featuresData enhancements Documentation Feedback 153 Glossary Glossary So on. See also row-major order 155 Also filename extension Memory fault 157 See ttv Index Symbols159