-qxlf90

Category

Language element control

Purpose

Provides compatibility with the Fortran 90 standard for certain aspects of the Fortran language.

Defaults

The default suboptions for -qxlf90 depend on the invocation command that you specify.

For the xlf95, f95, xlf95_r, xlf2003, f2003, xlf2003_r, xlf2008, f2008, or xlf2008_r command, the default suboptions are signedzero, autodealloc, and nooldpad .

For all other invocation commands, the defaults are nosignedzero, noautodealloc and oldpad .

Parameters

signedzero | nosignedzero

Determines how the SIGN(A,B) function handles signed real 0.0.If you specify the -qxlf90=signedzero compiler option, SIGN(A,B) returns -|A| when B=-0.0. This behavior conforms to the Fortran 95 standard and is consistent with the IEEE standard for binary floating-point arithmetic. Note that for the REAL(16) data type, XL Fortran never treats zero as negative zero.

This suboption also determines whether a minus sign is printed in the following cases:

• For a negative zero in formatted output. Again, note that for the REAL(16) data type, XL Fortran never treats zero as negative zero.
• For negative values that have an output form of zero (that is, where trailing non-zero digits are truncated from the output so that the resulting output looks like zero). Note that in this case, the signedzero suboption does affect the REAL(16) data type; non-zero negative values that have an output form of zero will be printed with a minus sign.

When using -qxlf90=nosignedzero, consider setting the -qstrict=nozerosigns option to improve performance.

autodealloc | noautodealloc

Determines whether the compiler deallocates allocatable objects that are declared locally without either the SAVE or the STATIC attribute and have a status of currently allocated when the subprogram terminates. This behavior conforms with the Fortran 95 standard. If you are certain that you are deallocating all local allocatable objects explicitly, you may want to turn off this suboption to avoid possible performance degradation.

oldpad | nooldpad

When the PAD=specifier is present in the INQUIRE statement, specifying -qxlf90=nooldpad returns UNDEFINED when there is no connection, or when the connection is for unformatted I/O. This behavior conforms with the Fortran 95 standard and above. Specifying -qxlf90=oldpad preserves the Fortran 90 behavior.

Related information

• See the SIGN information in the Intrinsic Procedures section and the Array concepts section.
• -qstrict