[Bug c++/84569] New: g++ -g -O3 consumes all memory

[jorrit at jorrit dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84569

            Bug ID: 84569
           Summary: g++ -g -O3 consumes all memory
           Product: gcc
           Version: 6.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jorrit at jorrit dot de
  Target Milestone: ---

Created attachment 43503
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43503&action=edit
reduced test case

Compiling the attached reduced test-case with -g -O3 eats more than 14G memory
(at which point I killed the compilation).

Compiling with -g -O2 or with -g -O3 -fno-var-tracking works fine.

This bug behaves similar to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77844
and was triggered the same of our unit tests, except that the reduced test of
77844 does not trigger with g++ 6.3.

Bug triggers with:
- g++ (Ubuntu 5.4.1-2ubuntu1~16.04) 5.4.1 20160904 from Ubuntu 16.04.3
- g++ (Debian 6.3.0-18+deb9u1) 6.3.0 20170516 from Debian stretch
- g++ (GCC) 6.4.0 from https://hub.docker.com/_/gcc/ (:6.4)

Bug does not trigger with:
- g++-7 (Ubuntu 7.2.0-1ubuntu1~16.04) 7.2.0 from 
  http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu xenial/main
- g++ (GCC) 7.3.0 from https://hub.docker.com/_/gcc/ (:latest)

See also:
- The corresponding bug in our gitlab
  https://gitlab.dune-project.org/core/dune-common/issues/115
- The old, similar GCC bug
  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77844
- The bug in our gitlab corresponding to the old GCC bug
  https://gitlab.dune-project.org/flyspray/FS/issues/1668