------- Comment #18 from rguenth at gcc dot gnu dot org 2009-04-04 17:57 ------- Patch posted: http://gcc.gnu.org/ml/gcc-patches/2009-04/msg00311.html
it will replace redundant PHI nodes with a copy, so <bb 4>: # c_1 = PHI <a_4(D)(2), b_7(D)(3)> # d_2 = PHI <a_4(D)(2), b_7(D)(3)> D.1599_10 = c_1 + d_2; will become <bb 4>: # c_1 = PHI <a_4(D)(2), b_7(D)(3)> d_2 = c_1 D.1599_10 = c_1 + d_2; to not immediately trigger PR23821 (of course the next copyprop will happily propagate c_1 into all uses of d_2). It does replace single-uses though, which does not increase register pressure. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28868
