HP Fortran Programmer's Guide (September 2007)

Using Fortran directives

Using HP Fortran directives

Chapter 9202

Using HP Fortran directives

HP Fortran provides a number of compiler directives that are useful for controlling certain

functions (for example, optimization) within the source ﬁle. Table 9-1 lists and brieﬂy

describes these directives; they are listed in the order in which they appear in the sections

below.

In ﬁles that use free format, directives must start with the comment character !. In ﬁxed

format, they must start with the comment character C, *,or! in column 1. Keywords and any

arguments must be delimited by at least one space character, as in the following:

!$HP$ OPTIMIZE ON

Table 9-1 HP Fortran directives

Directive Function

$HP$ ALIAS Associates the name of a subroutine,

function, entry, or common block with an

external name.

$HP$ CHECK_OVERFLOW Generates code to trap integer overﬂows.

$HP$ LIST Controls output of source lines in listing

ﬁle.

$HP$ OPTIMIZE Controls optimization within the source

ﬁle.

$HP$ ESTIMATED

FREQUENCY

Passes on to the compiler an estimate of

how frequently the current block is

executed.

If the current block is an 'if' block, then 'f'

must be 0 <= f <= 1. In this case, 'f'

indicates the probability of executing this

block compared to the corresponding 'if'

block. If the current block is a loop, then 'f'

must be f >= 0. In this case, 'f' indicates

the number of times the loop might get

executed (trip count).