[Bug c/78885] New: gcac checking too slow to be useful ?

["dcb314 at hotmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78885

            Bug ID: 78885
           Summary: gcac checking too slow to be useful ?
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

I just tried out a plain non-bootstrap build
of gcc trunk using --enable-checking=gcac. 

Configure line was

../trunk/configure --prefix=/home/dcb/gcc/results.243837 \
        --disable-bootstrap \
        --disable-multilib \
        --disable-werror \
        --enable-checking=gcac \
        --enable-languages=c,c++,fortran

In the build, some compilations took over an hour on a 4GHZ
AMD machine. Using ulimit -t 3600 meant the build would not complete.

I checked how many times gcac gets mentioned in this
bug database. To my surprise, only two mentions, so the
gcac checking isn't helping to find bugs very much.

Suggest rework gcac checking option to be fast enough
to be usable. 

Splitting gcac into a fast checker that doesn't check much and 
a full-fat checker that does as much as the current version
might be the way forward.