I noticed this late last year, now is the proper time to change it. Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard. 2016-05-18 Richard Biener <rguent...@suse.de> * passes.def: Put late dse and cd_dce in canonical order. Index: gcc/passes.def =================================================================== --- gcc/passes.def (revision 236357) +++ gcc/passes.def (working copy) @@ -315,8 +315,8 @@ along with GCC; see the file COPYING3. only examines PHIs to discover const/copy propagation opportunities. */ NEXT_PASS (pass_phi_only_cprop); - NEXT_PASS (pass_cd_dce); NEXT_PASS (pass_dse); + NEXT_PASS (pass_cd_dce); NEXT_PASS (pass_forwprop); NEXT_PASS (pass_phiopt); NEXT_PASS (pass_fold_builtins);