Peter Jansen wrote:
Hi Ivan,
The bigger code problem in your case is caused by GCC4 inlining
some functions by default. For example, an non-static inline
function, that is used only a single time (such as init_SPI
in your case), is included in the object file twice (the function
itself and its inline call). If you specify the
-ffunction-sections attribute (and use the -gc-sections linker
switch), the code size will be less than using GCC v3.
If you don't want to use the -ffunction-sections, you either need
to disable inlining completely (-fno-inline), or tweak the
maximum inlined function size (-finline-limit=x), that is
more precise.
Thanks, the fno-inline works and reduces the code.
Of course, the best way is to correct your code! Functions and data
that are not exported from a module should always be declared "static".
That way the compiler will inline single-use functions and omit the
non-inline version entirely. This will give the compiler the best
chance to make the code smaller and faster.
With gcc 4.3, it is also possible to compile and link all your source
code on a single line and use the "-combine" and "-fwhole-program"
options. This lets the compiler know that it has full information about
all code, and will give inter-module inter-function optimisation. It
can make debugging a little inconvenient, of course, as with any
powerful optimisation.
