reload.c:operands_match_p does not do big endian adjustment for floating point operands. Hence, when you have a pattern that needs such a match, you get an ICE saying that the insn does not match its constraints.
Subject: Bug number PR middle-end/29847 A patch for this bug has been added to the patch tracker. The mailing list url for the patch is http://gcc.gnu.org/ml/gcc-patches/2006-11/msg01074.html