------- Comment #4 from ebotcazou at gcc dot gnu dot org 2010-01-12 08:57 ------- > Then gcc comes to line3657. Since changed_i3_dest is 0, gcc does not > call adjust_for_new_dest at all. > > line3657: > if (changed_i3_dest) > { > PATTERN (i3) = newpat; > adjust_for_new_dest (i3); > }
We should try and set changed_i3_dest to 1 in this particular case as well. Where does the dest get changed exactly? > I did not read the entire combine pass. So I am not sure whether it is > fine to just add something like this after line3062 where > recog_for_combine is called. > > if (insn_code_number >= 0) > changed_i3_dest = 1; Too big a hammer, the dest of I3 is generally not changed. > Another option to fix this problem is not to attach REG_EQUAL note to > "set subreg reg" at all during forward propagation. Too big a hammer as well, the note is correct at this point. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42691