topic Re: excessively large executables in Operating System - HP-UX

excessively large executables

Michael Murphy_2 — Wed, 18 Feb 2004 14:30:56 GMT

Hello,

I have a machine that has executables created by developers that are very large (>50meg and some libs >200 meg). I suspect that they are linking in some large libraries that may not be needed. Any tools available to investigate what is contained in a c++ exec, and whether libs linked in are in fact used?

Thanks...

Re: excessively large executables

A. Clay Stephenson — Wed, 18 Feb 2004 14:37:40 GMT

I'm willing to bet that these are statically linked executables. That can be good from the standpoint that the developer knows that they will run on any system but it does produce large, memory-wasteful executables.

Do a chatr filename. If you see no shared libraries listed then you are statically linked. Ldd can also be used. It will either report the shared libraries utilized or it will report ' "myfile" is not a shared executable' -- indicating that "myfile" is statically linked.

Man chatr, ldd for details.

Re: excessively large executables

Gregory Fruth — Thu, 19 Feb 2004 13:55:09 GMT

Use "ldd" or "chatr" to see what shared
libraries are in an executable. If the
library was an archive library, I don't
know of a tool that can get the library
name. But you can use "nm" to snoop around
to see what objects are in the executable.

However, I don't think the linker will link
in library code that's not used (either
archive or shared). One thing that can
bloat executables is having a lot of
initialized arrays:

double a[100000] = {0, 1, ...};

The compiler will make space in the
executable for the entire array.
Unitialized arrays (the same as above,
minus the = {0, 1, ...} part) are set up
at run time.

Use the "size -v" commmand to see how
much space is being used in an executable
for each type of data. In the "size -v"
output, $CODE is the program's executable
code, $BSS contains the unitialized arrays
and variables, and $DATA is the initialized
arrays and variables.

HTH