Kenwood HP 9000 manual

	Creating and Using Libraries
	Creating Shared Libraries
b.o	A huge module, but contains only error routines that
	are seldom called.
c.o	Contains routines that are called frequently by a.o,
	and calls routines in a.o frequently.

If you create a shared library using the following command line, the modules will be inserted into the library in alphabetical order:

$ ld -b -o libabc.sl *.o

The potential problem with this ordering is that the routines in a.o and c.o are spaced far apart in the library. Better virtual memory performance could be attained by positioning the modules a.o and c.o together in the shared library, followed by the module b.o. The following command will do this:

$ ld -b -o libabc.sl a.o c.o b.o

One way to help determine the best order to specify the object files is to gather profile data for the object modules; modules that are frequently called should be grouped together on the command line.

Another way is to use the lorder(1) and tsort(1) commands. Used together on a set of object modules, these commands determine how to order the modules so that the linker only needs a single pass to resolve references among the modules. A side-effect of this is that modules that call each other may be positioned closer together than modules that don't. For instance, suppose you have defined the following object modules:

Module	Calls Routines in Module
a.o	x.o y.o
b.o	x.o y.o
d.o	none
e.o	none
x.o	d.o
y.o	d.o

Then the following command determines the one-pass link order:

$ lorder ?.o tsort	Pipe lorder's output to tsort.
a.o
b.o
e.o
x.o

Chapter 5 147