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

-qxlf90 Option
Syntax
-qxlf90={settings}
XLF90({settings})
Provides backward compatibility with XL Fortran for AIX Version 5 and 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, xlf95_r , or xlf95_r7 command, the default suboptions are
signedzero and autodealloc. For all other invocation commands, the defaults are
nosignedzero and noautodealloc.
Arguments
signedzero | nosignedzero
Determines how the SIGN(A,B) function handles signed real 0.0. Prior to
XL Fortran Version 6.1, SIGN(A,B) returned |A| when B=-0.0. This
behavior conformed with the Fortran 90 standard. Now, 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:
v
For a negative zero in formatted output. Again, note that for the
REAL(16) data type, XL Fortran never treats zero as negative zero.
v 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.
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 and did not exist in XL
Fortran prior to Version 6.1. If you are certain that you are deallocating all
local allocatable objects explicitly, you may wish to turn off this suboption
to avoid possible performance degradation.
XL Fortran Compiler-Option Reference 263