Code Optimization

Code Optimization

[Taha Mannan Jiruwala]

Hi,

I have around 10k lines of C++ code on linux.
I want to know of any pointers for Code Optimization Techniques
using compiler and linker options. I am using g++.

regards,
taha

Re: Code Optimization

[Taha Mannan Jiruwala]

I have checked the gcc manual and found some useful options.

I think I have not put my problem statement clearly, here it goes:
Basically my goal is to reduce the code footprint without significant
reduction in performance.
----------------------------------------------------------------------
My application has a set of libraries and executables
- When I link them statically, the exe sizes increase
- When I make them shared libraries, the performance of my application is
affected drastically.

My Approach:
- Reduce library size
- Find a shared library solution that is efficient (Does not drastically
reduce performance, may be something Intermediate to shared and static
approach)

TIA,
taha


Ben Elliston wrote:

> >>>>> "Taha" == Taha Mannan Jiruwala <taha@sasken.com> writes:
>
>   Taha> I want to know of any pointers for Code Optimization Techniques
>   Taha> using compiler and linker options. I am using g++.
>
> Have you checked the GCC manual?
>
> Ben

Re: Code Optimization

[Alexandre Oliva]

On Oct  7, 2002, Taha Mannan Jiruwala <taha@sasken.com> wrote:

> I think I have not put my problem statement clearly

In fact, you haven't even mentioned which architecture you're
targeting.  This can make a lot of difference as to the set of options
available.

> - Find a shared library solution that is efficient (Does not drastically
> reduce performance, may be something Intermediate to shared and static
> approach)

You may try to create dynamic libraries out of non-PIC.  Assuming this
is an IA32 architecture (in which -fPIC makes a lot of difference
given how register-starved it is), it can help speed up the
application code, at the expense of a lot of additional run-time
relocations, that will impact library load time.

Unfortunately, if you care about portability across multiple targets,
then creating dynamic libraries out of non-PIC is not an option.

You may consider using symbols of hidden visibility within the shared
library, such that function calls don't have to go through a PLT.
This may save space (for relocations), time (for relocations and
function calls).

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                 aoliva@{redhat.com, gcc.gnu.org}
CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist                Professional serial bug killer