https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82494
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- I commented in the dup: This code hasn't been fixed to avoid overflows and generally expects to operate with infinite precision integers ... (you know, 32/64bits will be enough - really!). Fixing requires overhauling all of the API and data structures in dependence analysis and finding a suitable representation for "infinite precision integers". Note that most of the APIs do not have a well-defined failure mode so bailing out isn't easy either. Using GMP is very likely prohibitly expensive not only due to its lack of optimizing the small-precision case. OTOH we are using it from niter analysis already. Evaluating ISL ints (isl/val.h when configured to not use GMP) might be worth, as well as maybe looking at including (patched?) mini-gmp (not sure if that plays well with linking against real gmp, but eventually mpfr plays well enough with mini-gmp and doesn't get too slow). Note the HWIs are less likely a problem than the ints currently used for lambda vectors/matrices. Note that simply silencing UBSAN by using unsigned arithmetic will simply silence it, not avoiding wrong-code issues that might be latent there.