How gcc handles alignment options

[Ian Lance Taylor]

Wei Hu <glegoo@gmail.com> writes:

> We know that GCC has options that control optimization.  What I tried
> to do was to align functions with the -falign-functions option.
> However I noticed that this option only controls the user code,
> without affecting the library instructions.

Correct.  The option only affects compilation.  It does not affect
linking.

> Although finally I modified linker script to fulfill my goal.  I still
> want to know how gcc handles the alignment options?
> I guess it does so by passing some option to ld..  But why doesn't the
> option affect the libraries?

-falign-functions doesn't pass anything to ld.  It just inserts .align
pseudo-ops to cause each function being compiled to be aligned.

Ian