http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51902
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-20 17:44:50 UTC --- The patch breaks g++.dg/guality/redeclaration1.C on i?86 -m32 -Os -g. The supercontext range has 3 elements, the same range child range has 2 elements, same as the first and last of the supercontext. So, either we'd need to stop optimizing if thiscount != supercount, or tweak somehow reorder_blocks_1 so that it clears BLOCK_SAME_RANGE even when it didn't show up adjacent to supercontext's NOTE_INSN_BLOCK_BEGIN resp. END.