------- Comment #1 from rguenth at gcc dot gnu dot org 2009-12-04 21:18 ------- This change merely turns off PRE in cold code regions. So if -fno-tree-pre breaks calculix for you I'd guess some later optimization manages to miscompile it (my guess: the vectorizer).
What options do you build calculix with? -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42286