Query on -ffunction-section & -fdata-sections options of gcc

Question

The below mentioned in the GCC Page for the function sections and data sections options:

-ffunction-sections
-fdata-sections

Answer 1

I tried it a while back and looking at the results it seems the size increase comes from the order of objects with different alignment. Normaly the linker sorts objects to keep the padding between them small but it looks like that only works within a section, not across the individual sections. So you often get extra padding between the data sections for each function increasing the overall space.

For a static lib with -Wl,-gc-sections the removal of unused section will most likely make more than up for the small increase though.