[Bug demangler/80002] New: quadratic behavior in demangler

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80002

            Bug ID: 80002
           Summary: quadratic behavior in demangler
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: demangler
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
  Target Milestone: ---

Playing with LibFuzzer turned up the following testcase:

c++filt
_ZcvT_IrcvT_IreloaT_IrcvT_IreloaT_IreloaT_IrcvT_IrleoaT_IrcvT_IreloaT_IreloaT_IrcvT_IrelcvT_IreloaT_ZcvT_IrcvT_IreloaT_IrcvT_IreloaT_IreloaT_IrcvT_IrleoaT_IrcvT_IreloaT_IreloaT_IrcvT_IrelcvT_IreloaT_ZcvT_IrcvT_IreloaT
takes 36 seconds


_ZcvT_IrcvT_IreloaT_IrcvT_IreloaT_IreloaT_IrcvT_IrleoaT_IrcvT_IreloaT_IreloaT_IrcvT_IrelcvT_IreloaT_ZcvT_IrcvT_IreloaT_IrcvT_IreloaT_IreloaT_IrcvT_IrleoaT_IrcvT_IreloaT_IreloaT_IrcvT_IrelcvT_IreloaT_ZcvT_IrcvT_IreloaT_IrcvT_IreloaT_
takes 2:30 minutes

_ZcvT_IrcvT_IreloaT_IrcvT_IreloaT_IreloaT_IrcvT_IrleoaT_IrcvT_IreloaT_IreloaT_IrcvT_IrelcvT_IreloaT_ZcvT_IrcvT_IreloaT_IrcvT_IreloaT_IreloaT_IrcvT_IrleoaT_IrcvT_IreloaT_IreloaT_IrcvT_IrelcvT_IreloaT_ZcvT_IrcvT_IreloaT_IrcvT_IreloaT_IreloaT_IrcvT_
takes 9 minutes 

etc...

If we want to add the demangler to https://github.com/google/oss-fuzz this
issue should be solved.