https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126081
--- Comment #4 from Stafford Horne <shorne at gcc dot gnu.org> --- Thanks cvise was what I was looking for, I was trying to reduce the reproduction case manually, this tool is great. Note it turns out the case passes fine with -O1,-O2,-O3, but fails with -Oz,-Os
