Pragma Directives

You typically use a #pragma directive to control the actions of the compiler in a particular portion of a program without affecting the program as a whole.

Put pragmas in your C++ source code where you want them to take effect. A pragma is in effect from the point where it is included to the end of the compilation unit or until another pragma changes its status.

A #pragma directive is an instruction to the compiler and is ignored during preprocessing.

Syntax:

#pragma pragma-string

pragma-string can be one of the following instructions to the compiler with any required parameters.

COPYRIGHT -- Specifies a copyright string.
COPYRIGHT_DATE -- Specifies a copyright date for the copyright string.
HP_SHLIB_VERSION -- Creates versions of a shared library routine.
LOCALITY -- Names a code subspace.
OPTIMIZE -- Turns optimization on or off.
OPT_LEVEL -- Sets an optimization level.
VERSIONID -- Specifies a version string.

Pragma OPTIMIZE

Syntax:

#pragma OPTIMIZE ON 
#pragma OPTIMIZE OFF

Description:

Turns optimization on or off.

Use this pragma to turn off optimization in sections of a source program.

NOTE:

You must specify one of the optimization options on the aCC command, otherwise this pragma is ignored.
This pragma cannot be used within a function.

Example:

aCC +O2 prog.C

#pragma OPTIMIZE OFF
void A(){    // Turn off optimization
    ...      // for this function
}

#pragma OPTIMIZE ON
void B(){    // Restore optimization
    ...      // to level 2.
}

Pragma OPT_LEVEL

Syntax:

#pragma OPT_LEVEL 1
#pragma OPT_LEVEL 2
#pragma OPT_LEVEL 3
#pragma OPT_LEVEL 4

Description:

The OPT_LEVEL pragma sets the optimization level to 1, 2, 3, or 4.

NOTE:

You must specify one of the optimization options on the aCC command, otherwise this pragma is ignored.
This pragma cannot raise the optimization level above the level specified in the command line.
This pragma cannot be used within a function.
OPT_LEVEL 3 and 4 are allowed only at the beginning of a file.

Example:

aCC -O prog.C

#pragma OPT_LEVEL 1
void A(){      // Optimize this function at level 1.
   ...
}
#pragma OPT_LEVEL 2
void B(){      // Restore optimization to level 2.
   ...
}

Pragma HP_SHLIB_VERSION

Syntax:

#pragma HP_SHLIB_VERSION ["]date["]

The date argument is of the form month/year, optionally enclosed in quotes.

month must be 1 through 12, corresponding to January through December.
year can be specified as either the last two digits of the year (94 for 1994) or a full year specification (1994). Two-digit year codes from 00 through 40 represent the years 2000 through 2040, respectively.

Description:

Creates different versions of a routine in a shared library.

HP_SHLIB_VERSION assigns a version number based on date to a module in a shared library. The version number applies to all global symbols defined in the module's source file.

This pragma should only be used if incompatible changes are made to a source file. If a version number pragma is not present in a source file, the version number of all symbols defined in the object module defaults to 1/90.

For More Information:

Pragma COPYRIGHT

Syntax:

#pragma COPYRIGHT "string"

string is the set of characters included in the copyright message in the object file.

Description:

Specifies a string to include in the copyright message and puts the copyright message into the object file.

If no date is specified (using pragma COPYRIGHT_DATE), the current year is used in the copyright message.

Examples:

Assuming the year is 1997, the directive

#pragma COPYRIGHT "Acme Software"

places the following string in the object code:

(C) Copyright Acme Software, 1997. All rights reserved.
No part of this program may be photocopied, reproduced, or
transmitted without prior written consent of Acme Software.

The following pragmas

#pragma COPYRIGHT_DATE "1990-1997"
#pragma COPYRIGHT "Brand X Software"

place the following string in the object code:

(C) Copyright Brand X Software, 1990-1997. All rights reserved.
No part of this program may be photocopied, reproduced, or
transmitted without prior written consent of Brand X Software.

NOTE: To see the COPYRIGHT string as well as any other strings in the object file, use the strings(1) command with the -a option for example:

strings -a ObjectFileName.o

Pragma COPYRIGHT_DATE

Syntax:

#pragma COPYRIGHT_DATE "string"

string is a date string used by the COPYRIGHT pragma.

Description:

Specifies a date string to be included in the copyright message.

Use the COPYRIGHT pragma to put the copyright message into the object file.

Example:

#pragma COPYRIGHT_DATE "1988-1992"

NOTE: To see the COPYRIGHT_DATE string as well as any other strings in the object file, use the strings(1) command with the -a option for example:

strings -a ObjectFileName.o

Pragma LOCALITY

Syntax:

#pragma LOCALITY "string"

string specifies a name to be used for a code subspace.

Description:

Specifies a name to be associated with the code written to a relocatable object module.

All code following the LOCALITY pragma is associated with the name specified in string. Code that is not headed by a LOCALITY pragma is associated with the name $CODE$ .

The smallest scope of a unique LOCALITY pragma is a function.

Example:

#pragma LOCALITY "MINE"

Builds the name $CODE$MINE$ and associates all code following this pragma with this name, unless another LOCALITY pragma is encountered.

Pragma VERSIONID

Syntax:

#pragma VERSIONID "string"

string is a string of characters that HP aC++ places in the object file.

Description:

Specifies a version string to be associated with a particular piece of code. The string is placed into the object file produced when the code is compiled.

Example:

#pragma VERSIONID "Software Product, Version 12345.A.01.05"

Places the characters Software Product, Version 12345.A.01.05 into the object file.

NOTE: To see the VERSIONID string as well as any other strings in the object file, use the strings(1) command with the -a option for example:

strings -a ObjectFileName.o