Steven, Zdenek 1) single_set is built on top of single_set2. 2) single_set_2 uses REG_UNUSED notes. 3) tree-ssa-loop-ivops.c:seq_cost uses single_set.
I can find no indication that rtl dfa is run here to provide the information for single_set to produce the correct answer. Inquiring minds want to know. Kenny
