optimization/6798: [3.2/3.3/3.4 regression] very long compile time with large case-statement

[Steven Bosscher]

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6798

For all others who're bug-hunting: There's a proposed fix for this one,
see: http://gcc.gnu.org/ml/gcc-patches/2003-02/msg01502.html
which continues the thread from
http://gcc.gnu.org/ml/gcc-patches/2003-02/msg01254.html