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The upstream PR tracks the current status, once it is done (not the case yet), we can start considering backports, but it will take a while, this isn't something that would have updates issued immediately like important security bugs.
The https://gcc.gnu.org/r246314 might be backportable provided sufficient testing, the other changes from the PR look too risky, but we could instead apply something that is being considered for 9/8 backports, which is punt in sink_clobbers for -O0 (maybe -O1 too) if we would move say more than 4096 clobbers, which would break the quadratic behavior.
I don't know what the generator that generates this kind of code is, but if I could suggest something, one wouldn't run into this behavior if the code used if (...) { ... } else { ... } rather than ?:, because the latter in C++ has the serious disadvantage that all temporaries need to stay around until the whole toplevel statement finishes, which causes those 80000 temporary destruction until the end of the whole statement, rather than destructing each temporary shortly after construction.
Oh, and forgot to say, easy workaround until this is fixed would be to add -fstack-reuse=named_vars (or -fstack-reuse=none) option for the problematic sources.