[Bug lto/54312] uniquify_nodes takes 12% of Mozilla LTO build

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54312

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-09-11 
11:03:52 UTC ---
Patch pre-approved (also for 4.7) if it passes your testing.