Hello Dmitry,
I use gcc-4.4.7 version. I also tryed to use gcc-4.6.3 and it didn't make any results also.
Did you use coreboot's reference toolchain or was it a gcc-4.6.3 from your distribution? If you didn't try the reference toolchain yet, it's worth it.
To build the reference toolchain, simply run make crossgcc from your coreboot top-level directory, and wait... abuild should use it automatically. For your manual make runs, you should remove `.xcompile` once the toolchain is build.
I don't understand the reasin why it may happen.
Me neither. Maybe you should also try to reset your coreboot checkout or even a fresh checkout if you did any changes.
Nico