ICE in int_mode_for_mode()

[David Miller]

For a few days a lot of new testsuite failures have popped up on sparc,
wherein int_mode_for_mode() gets called with "VOIDmode" as an argument
from extract_bit_field_1 because "op0" is "(const_int 0)"

I have a feeling this is a known problem, but I couldn't find any
discussions about this.

I strongly suspect the following change caused this problem:

2011-11-16  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>

	PR middle-end/50325
	* expmed.c (store_bit_field_1): Use extract_bit_field on big
	endian targets if the source cannot be exactly covered by word
        mode chunks.