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

Other Environment Variables That Affect Run-Time Behavior
The LIBPATH and TMPDIR environment variables have an effect at run time, as
explained in “Correct Settings for Environment Variables” on page 12. They are not
XL Fortran run-time options and cannot be set in either XLFRTEOPTS or
XLSMPOPTS.
XL Fortran Run-Time Exceptions
The following operations cause run-time exceptions in the form of SIGTRAP
signals, which typically result in a “Trace/BPT trap” message:
v Fixed-point division by zero.
v Character substring expression or array subscript out of bounds after you
specified the -C option at compile time.
v Lengths of character pointer and target do not match after you specified the -C
option at compile time.
v The flow of control in the program reaches a location for which a semantic error
with severity of S was issued when the program was compiled.
v Floating-point exceptions occur after you specify the appropriate -qflttrap
suboptions at compile time.
v Floating-point operations that generate NaN values and loads of the NaN values
after you specify the -qfloat=nanq option at compile time.
If you install one of the predefined XL Fortran exception handlers before the
exception occurs, a diagnostic message and a traceback showing the offset within
each routine called that led to the exception are written to standard error after the
exception occurs. The file buffers are also flushed before the program ends. If you
compile the program with the -g option, the traceback shows source line numbers
in addition to the address offsets.
You can use a symbolic debugger to determine the error. dbx provides a specific
error message that describes the cause of the exception.
Related Information: See “-C Option” on page 103, “-qflttrap Option” on page
165, and “-qsigtrap Option” on page 232.
See “Detecting and Trapping Floating-Point Exceptions” on
page 296 for more details about these exceptions and
“Controlling the Floating-Point Status and Control Register”
on page 299 for a list of exception handlers.
66 XL Fortran Enterprise Edition for AIX : User’s Guide