title: Same source code, different executable size?
body: <p>In AIX, can different versions of compiler makes executables(or libraries) size different?</p>
  
  <h2>Questions</h2>
  
  <p>What can affects on size of executable/libraries?</p>
  
  <ul>
  <li>Different version of compiler.</li>
  <li>Different compile options.</li>
  <li>Different os version and its libraries(like libm.a, libpthread.a ..).</li>
  <li>More?</li>
  </ul>
  
  <h2>Some background.</h2>
  
  <p>In here, we have bunch of old executables and libraries which are not source code under version control. We need to figure out the executables are built from source code we have. So we build it again, but the result(exec, libs) is not same in size.</p>
  
  <h2>Tries..</h2>
  
  <p>I tried..</p>
  
  <ul>
  <li>dump -X64 -c : it shows some infos of compiler that was used when build it. The binarie's compiler version is 'IBM XL C/C++ .. 11.1.0.14'. But compiler's version which we have is 'IBM .. 11.1.0.13'. Can these make difference?</li>
  <li>ar -X64 -x : comparing extracted files from archive. when I do "make" some library, object files(*.o) were generated. most of files are same in size, but some's are not same. When dump them(files that has different size), the compiler is not same.</li>
  </ul>
  
  <p>Any help, advice, links will be helpful. Thank you.</p>