[Bug tree-optimization/58791] [4.9 Regression] Reassoc reuses SSA_NAMEs

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58791

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 31043
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31043&action=edit
gcc49-pr58791.patch

Preliminary patch that fixes linearize_tree and rewrite_expr_tree.  There are
various other places that need verification.