[Bug tree-optimization/56294] BOOT_CFLAGS='-O2 -g -fno-ipa-sra' leads to bootstrap comparison failure

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56294

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #19 from Richard Biener <rguenth at gcc dot gnu.org> 2013-03-06 09:45:11 UTC ---
Ok, with some added debug printing I see

 Updating SSA:
 creating PHI node in block #6 for elim_cost$cost
 creating PHI node in block #17 for elim_cost$cost
-creating PHI node in block #19 for cost$cost
 creating PHI node in block #6 for elim_cost$complexity
+creating PHI node in block #19 for cost$cost

that's obviously a problem (creating a PHI node involves creating a new
SSA name).  That's because we insert new PHI nodes for to rename symbols
via

      FOR_EACH_VEC_ELT (symbols_to_rename, i, sym)
        insert_updated_phi_nodes_for (sym, dfs, blocks_to_update,
                                      update_flags);

but we need to visit that in UID order ...

I have a patch.