[Bug c/68173] gcc does not terminate with -O0 on source file with a very large expression

[fuz at fuz dot su]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68173

--- Comment #4 from Robert Clausecker <fuz at fuz dot su> ---
No, it wasn't swapping, although I probably didn't let it run long enough to
exhaust all my memory (8 GiB). Either way, the file compiles pretty quickly
with -O3 so something seems to be wrong when no optimizations (-O0) take
considerably longer than many optimizations (-O3).