usepcomp

Option Type	Default Value	#pragma options	C	C++
-qoption	nousepcomp	-	x	x

Syntax

    -qusepcomp | -qusepcomp=directory | -qnousepcomp

Purpose
Uses a precompiled header file if no included files that have not changed since the precompiled header was created. This may help improve compile time.

Notes
Usage modes for usepcomp are:

-qusepcomp	Uses the precompiled header file called csetc.pch, if it exists in the current directory.
-qusepcomp=directory	Uses a precompiled header file if: directory is the name of an existing directory, and the csetc.pch precompiled header file exists in that directory. a directory with the name directory does not exist, but a precompiled header file called directory exists in the current directory.
-qnousepcomp	Does not use precompiled header files.

The -qusepcomp and -qgenpcomp options are designed to be used together, but they may be used separately.

-qgenpcomp used alone will refresh the contents of the precompiled header file, even if it already exists. This is useful if the file has been corrupted.
-qusepcomp used alone will use an existing precompiled header file without creating a new one. This is useful if you only want do not want the precompiled header file to be recompiled, or if remaining disk space is low.

When -qusepcomp and -qgenpcomp are used together, the compiler will automatically maintain and use a current precompiled header.

If you update your system header files, you can regenerate them with the /usr/ibmcxx/bin/mkpcomp command.

Precompiled headers will only be used at the same language level used during their creation.

For a given #include, -qusepcomp is checked first. Then the compiler checks for a precompiled version of the file to be included if such is specified. If it is found and it is current, it is used.

If a precompiled header is not being used (for example, if a current one is not found, or if -qusepcomp is not specified), and -qgenpcomp is specified, the compiler will create a new precompiled header (even if it exists and is current).

The precompiled headers created by installing IBM C and C++ Compilers are listed in the LPP inventory, and are removed if you uninstall IBM C and C++ Compilers. Any additional headers you create are not removed during uninstall.

Creating and Using Precompiled Header Files

List of Compiler Options and Their Defaults