[Bug middle-end/57780] Wasted work in subst_dup()

[pchang9 at cs dot wisc.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57780

--- Comment #1 from Po-Chun Chang <pchang9 at cs dot wisc.edu> ---
Patch sent to gcc-patches@

http://gcc.gnu.org/ml/gcc-patches/2013-07/msg00970.html