XL Fortran Enterprise Edition for AIX : User's Guide - IBM

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READ(unit_number,ID=idvar) a .... WAIT(ID=idvar) .... 2. In a WAIT statement with the DONE= specifier, the WAIT statement returns the completion status of an asynchronous I/O statement: integer idvar logical done integer, dimension(1000):: a .... READ(unit_number,ID=idvar) a .... WAIT(ID=idvar, DONE=done) .... The variable you specified in the DONE= specifier is set to ″true″ if the corresponding asynchronous I/O statement completes. Otherwise, it is set to ″false″. The actual data transfer can take place in the following cases: v During the asynchronous READ or WRITE statement v At any time before the execution of the corresponding WAIT statement v During the corresponding WAIT statement Because of the nature of asynchronous I/O, the actual completion time of the request cannot be predicted. You specify Fortran asynchronous READ and WRITE statements by using the ID= specifier. The value set for the ID= specifier by an asynchronous READ or WRITE statement must be the same value specified in the ID= specifier in the corresponding WAIT statement. You must preserve this value until the associated asynchronous I/O statement has completed. The following program shows a valid asynchronous WRITE statement: program sample0 integer, dimension(1000):: a integer idvar a = (/(i,i=1,1000)/) WRITE(10,ID=idvar) a WAIT(ID=idvar) end The following program is not valid, because XL Fortran destroys the value of the asynchronous I/O identifier before the associated WAIT statement: program sample1 integer, dimension(1000):: a integer idvar a = (/(i,i=1,1000)/) WRITE(10,ID=idvar) a idvar = 999 ! Valid id is destroyed. WAIT(ID=idvar) end An application that uses asynchronous I/O typically improves performance by overlapping processing with I/O operations. The following is a simple example: program sample2 integer (kind=4), parameter :: isize=1000000, icol=5 integer (kind=4) :: i, j, k integer (kind=4), dimension(icol) :: handle 336 XL Fortran Enterprise Edition for AIX : User’s Guide
integer (kind=4), dimension(isize,icol), static :: a, a1 ! ! Opens the file for both synchronous and asynchronous I/O. ! open(20,form="unformatted",access="direct", & status="scratch", recl=isize*4,asynch="yes") ! ! This loop overlaps the initialization of a(:,j) with ! asynchronous write statements. ! ! NOTE: The array is written out one column at a time. ! Since the arrays in Fortran are arranged in column ! major order, each WRITE statement writes out a ! contiguous block of the array. ! do 200 j = 1, icol a(:,j) = (/ (i*j,i=1,isize) /) write(20, id=handle(j), rec=j) a(:,j) 200 end do ! ! Wait for all writes to complete before reading. ! do 300 j = 1, icol wait(id=handle(j)) 300 end do ! ! Reads in the first record. ! read(20, id=handle(1), rec=1) a1(:,1) do 400 j = 2, icol k = j - 1 ! ! Waits for a previously initiated read to complete. ! wait(id=handle(k)) ! ! Initiates the next read immediately. ! read(20, id=handle(j), rec=j) a1(:,j) ! ! While the next read is going on, we do some processing here. ! do 350 i = 1, isize if (a(i,k) .ne. a1(i,k)) then print *, "(",i,",",k,") & & expected ", a(i,k), " got ", a1(i,k) end if 350 end do 400 end do ! ! Finish the last record. ! wait(id=handle(icol)) do 450 i = 1, isize if (a(i,icol) .ne. a1(i,icol)) then print *, "(",i,",",icol,") & & expected ", a(i,icol), " got ", a1(i,icol) end if Implementation Details of XL Fortran Input/Output 337
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XL Fortran Enterprise Edition for A
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Note! Before using this information
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Options That Control Listings and M
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How XLF I/O Interacts with Pipes, S
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viii XL Fortran Enterprise Edition
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x XL Fortran Enterprise Edition for
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The following performance-related d
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How to Read the Syntax Diagrams and
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v Optionally, enter the value of at
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6 XL Fortran Enterprise Edition for
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Migration Support The XL Fortran co
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These items are located, or accesse
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v /usr/share/man/info/en_US/xlf/pos
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Notes: 1. Specifying the LC_ALL env
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3. Installing a compiler program te
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fsuffix cppsuffix osuffix ssuffix l
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mcrt = /lib/mcrt0_r.o gcrt = /lib/g
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options include -L/usr/lpp/xlf/lib,
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Related Information: You can use th
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Table 1. Potential Problems Migrati
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Table 1. Potential Problems Migrati
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►► xlf90 xlf90_r xlf90_r7 xlf95
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xlf90, xlf90_r, and xlf90_r7 comman
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Related Information: The ssuffix at
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Related Information: See “-qpdf O
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The @PROCESS compiler directive mus
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Passing Fortran Files through the C
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the trigraph sequence. XL Fortran u
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The configuration file /etc/xlf.cfg
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esulting program work as you expect
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v v Do not use names that are the s
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v v Build the application by using
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If you have applications in which F
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total_usertime Returns the total us
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To obtain support for items that ar
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Note: You may need the old setting
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These partitions are then assigned
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During the busy-wait search for wor
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(for example, loops for which you s
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Other Environment Variables That Af
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Options That Control Input to the C
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Table 3. Options That Control Input
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Table 5. Options for Performance Op
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Table 5. Options for Performance Op
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Table 6. Options for Debugging and
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Table 7. Options That Control Listi
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Table 8. Options for Compatibility
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v v Determine names and options for
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Detailed Descriptions of the XL For
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-1 Option Syntax -1 ONETRIP | NOONE
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-b64 Option Syntax -b64 The AIX ope
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Examples xlf95 f.f -brtl -bshared -
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-bloadmap Option Syntax -bloadmap:n
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-brtl Option Syntax -brtl | -bnortl
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-bstatic Option Related Information
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-c Option Syntax -c Prevents the co
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-d Option Syntax -d Causes preproce
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-g Option Syntax -g DBG | NODBG Gen
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-k Option Syntax -k FREE(F90) Speci
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-l Option Syntax -lkey Searches the
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-O Option Syntax -O[level] OPTimize
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-o Option Syntax -o name Specifies
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-p Option Syntax -p[g] Sets up the
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-q32 Option Related Information See
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-qalias Option Syntax -qalias={[no]
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equivalence (a, b(3)) t = b; a = t
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a derived type are stored with suff
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pwr2s p2sc You can run the executab
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v v If your primary concern is exec
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-qassert Option Syntax -qassert={de
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-qautodbl Option Syntax -qautodbl=s
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Related Information For background
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2 Level-2 cache or the table lookas
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-qcheck Option Syntax -qcheck | -qn
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-qcompact Option Syntax -qcompact |
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-qctyplss Option Syntax -qctyplss[(
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-qdbg Option Syntax -qdbg | -qnodbg
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-qdirective Option Syntax -qdirecti
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-qdirectstorage Option Syntax -qdir
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-qdpc Option Syntax -qdpc[=e] | -qn
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-qescape Option Syntax -qescape | -
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-qextchk Option Syntax -qextchk | -
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-qextname Option Syntax -qextname[=
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-qfdpr Option Syntax -qfdpr | -qnof
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-qflag Option Syntax -qflag=listing
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the reciprocal of the divisor. It a
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export SQRT_EXCEPTION=3.1 166 XL Fo
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-qfree Option Syntax -qfree[={f90|i
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-qhalt Option Syntax -qhalt=severit
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If you specify -qhot=novector, the
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-qhssngl Option Syntax -qhssngl | -
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-qinit Option Syntax -qinit=f90ptr
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v You can specify alphabetic digits
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-qintsize Option Syntax -qintsize=b
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-qipa Option Syntax -qipa[=suboptio
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If you specify short, the Object Fi
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Table 15. Regular expression syntax
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-qkeepparm Option Syntax -qkeepparm
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Restrictions The -qflag option can
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-qlibansi Option Related Informatio
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-qlibposix Option Related Informati
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-qlistopt Option Syntax -qlistopt |
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-qlog4 Option Syntax -qlog4 | -qnol
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Restrictions Depending on the sourc
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-qmixed Option Syntax -qmixed | -qn
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-qmodule Option Syntax -qmodule=man
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-qnullterm Option Syntax -qnullterm
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-qonetrip Option Syntax -qonetrip |
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-qpdf Option Syntax -qpdf{1|2} Tune
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mergepdf Generates a single pdf rec
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-qphsinfo Option Syntax -qphsinfo |
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-qpic Option Syntax -qpic[=suboptio
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sce | nosce } else if (a == 3) *res
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-qprefetch Option Syntax -qprefetch
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-qrealsize Option Syntax -qrealsize
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-qrecur Option Syntax -qrecur | -qn
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To produce a listing file that you
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-qsave Option Syntax -qsave[={all|d
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-qsclk Option Syntax -qsclk[=centi
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-qsigtrap Option Syntax -qsigtrap[=
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-qsmp Option Syntax -qsmp[=suboptio
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threshold=n The work in a partition
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xlf90 -qsmp=noopt -O3... is equival
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-qspillsize Option Syntax -qspillsi
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-qstrictieeemod Option Syntax -qstr
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-qsuffix Option Syntax -qsuffix=opt
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Examples @process nullterm i = 1; j
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Related Information See the OpenMP
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-qthreaded Option Syntax -qthreaded
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If you do not specify -qtune, its s
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-qundef Option Syntax -qundef | -qn
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-qunwind Option Syntax -qunwind |-q
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-qwarn64 Option See “-qwarn64 Opt
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-qxflag=xalias Option Syntax -qxfla
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intxor | nointxor Treats .XOR. as a
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Examples Consider the following pro
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In this example, conditional compil
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-qzerosize Option Syntax -qzerosize
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-t Option Syntax -tcomponents Appli
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-u Option Syntax -u UNDEF | NOUNDEF
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-V Option Syntax -V This option is
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$ ./a.out 1 2 3 4 276 XL Fortran En
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-y Option Syntax -y{n | m | p | z}
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64-Bit Thread Support On AIX Versio
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-q64 Option Syntax -q64[=largetype]
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-qwarn64 Option Syntax -qwarn64 | -
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Page 302 and 303: v v If the data or program code con
Page 304 and 305: v Comparisons involving NaN values
Page 306 and 307: How XL Fortran Rounds Floating-Poin
Page 308 and 309: 2. For thread-safety and reentrancy
Page 310 and 311: v The fltint suboption speeds up fl
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Page 314 and 315: Another method is to use the ieee_s
Page 316 and 317: call fpgets(fpstat) fpstat(fpox) =
Page 318 and 319: The following example shows the dif
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Page 322 and 323: Optimization levels Option -qnoopt/
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Page 326 and 327: v v v Reducing the costs of memory
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Page 332 and 333: # Let the compiler decide (relative
Page 334 and 335: can also use the SNAPSHOT directive
Page 336 and 337: -qipa=list cross-file type checking
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Page 340 and 341: Stream-access formatted files: A re
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Page 356 and 357: v The result of an application does
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Page 360 and 361: v v The XL compilers generate code
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Page 370 and 371: The system linkage convention passe
Page 372 and 373: Run-time Stack for 32-bit Environme
Page 374 and 375: processing, and the fifth doublewor
Page 376 and 377: v v v v v v v In a 32-bit Environme
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Page 380 and 381: Function Values Functions return th
Page 382 and 383: Example The control structure has t
Page 384 and 385: technique can reduce the amount of
Page 386 and 387: Note: When you run an XL Fortran pr
Page 388 and 389: Duplicating Extensions from Other S
Page 390 and 391: Input/Output Errors If the error de
Page 392 and 393: -> xlf95 -qddim -g testprog.f -o te
Page 394 and 395: 7. The next step is to research why
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Page 398 and 399: v v Memory leak reporting that indi
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HD_FILL HD_STACK=n called a certain
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388 XL Fortran Enterprise Edition f
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Source Section The source section c
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Attribute and Cross-Reference Secti
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Automating Large, Complex Compilati
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For fixed source form code, in addi
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Common Industry Extensions That XL
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Example 2 - Valid C Routine Source
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close(10) open(10, file="fun10.out"
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!**********************************
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operating system require the same o
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Examples of Storage Relationships f
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0 4 8 16 32 64 COMPLEX (16) COMPLEX
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! Data values between r8 and x16 ar
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end function sqrt real*8 function r
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Table 34. MASS Vector Library Funct
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IBM may use or distribute any of th
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ind. To relate an identifier to ano
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expression. A sequence of operands,
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name. A lexical token consisting of
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labels can be used to transfer cont
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.profile file 12 .s files 33, 34 .X
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fdate_ service and utility subprogr
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nonested_par suboption of -qsmp 234
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vi text editor 29 W W error severit
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