a gcc compiler optimization problem from my colleague

function-section

data-section

Could any one tell what exactly these two option do. I have not been

able to understand why we use them because as per the gcc man page,

these options increase the size of libraries and exe

This group is not appropriate to answer your question.

cf. http://gcc.gnu.org/lists.html

http://gcc.gnu.org/onlinedocs/gcc-4.2.1/gcc/Optimize-Options.html

-ffunction-sections

-fdata-sections

Place each function or data item into its own section in the output file if the target supports arbitrary sections. The name of the function or the name of the data item determines the section's name in the output file.

Use these options on systems where the linker can perform optimizations to improve locality of reference in the instruction space. Most systems using the ELF object format and SPARC processors running Solaris 2 have linkers with such optimizations. AIX may have these optimizations in the future.

Only use these options when there are significant benefits from doing so. When you specify these options, the assembler and linker will create larger object and executable files and will also be slower. You will not be able to use gprof on all systems if you specify this option and you may have problems with debugging if you specify both this option and -g.

http://coding.derkeiler.com/Archive/C_CPP/comp.lang.c/2007-08/msg00245.html

http://debugerror.blog.ccidnet.com/blog-htm-itemid-273860-do-showone-type-blog-uid-68775.html

http://sources.redhat.com/ml/crossgcc/2006-10/msg00036.html

http://www.nuoya.org/bbs/forum_posts.asp?TID=163&PN=1