On Linux/x86-64, revision 187678 miscompiled 403.gcc in SPEC CPU 2006 with -DSPEC_CPU -DNDEBUG -I. -O2 -ffast-math -fwhole-program -flto=jobserver -fuse-linker-plugin I got 166.i:10048: Internal compiler error in simplify_gen_subreg, at simplify-rtx.c:2755 Revision 187620 is OK.
It is caused by revision 187631: http://gcc.gnu.org/ml/gcc-cvs/2012-05/msg00628.html
Hopefully fixed now (r189260) - please re-open if not.