[U-Boot] [PATCH 62/71] serial: spl: Implement empty functions for SPL

[Marek Vasut]

Dear Tom Rini,

> On 09/18/12 11:33, Marek Vasut wrote:
> > Dear Scott Wood,
> 
> [snip]
> 
> >> I think I got some wires crossed and was thinking about
> >> printf/puts. We want those to be optimized away at compile time
> >> (not pointed to a stub at link time) on an SPL that has no output
> >> support, but once that's done the low level serial functions
> >> shouldn't be referenced anymore, right?
> > 
> > But if you point them to stubs, that's OK. The compiler will GC
> > these useless stubs anyway. But wait, we're getting to LTO here,
> > right?
> > 
> > So the safest bet really is macro in serial.h ?
> 
> Due to the gcc bug I've mentioned before, yes.  Dummy functions will,
> I bet, keep the string constants around.  do {} while(0) will drop
> them out entirely.

Damn, not much gain on m28evk (with C functionss/with macros), using gcc 4.7.1:

Configuring for m28evk board...
   text    data     bss     dec     hex filename
 418994    7780  288632  715406   aea8e ./u-boot
  11773     788      12   12573    311d ./spl/u-boot-spl

Configuring for m28evk board...
   text    data     bss     dec     hex filename
 418998    7780  288628  715406   aea8e ./u-boot
  11765     788      12   12565    3115 ./spl/u-boot-spl

Best regards,
Marek Vasut