https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79265
--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> --- There are two major reasons for the forcing of -fno-delete-null-pointer-checks by the null pointer sanitizers. One is to avoid relying too much on UB assumptions, where the optimizers say that something can't be NULL e.g. based on nonnull/returns_nonnull attributes and various other cases, which can't happen in valid code, but can happen in invalid code the sanitizers are trying to help diagnose. And the second reason is that the sanitization itself is performed by comparing pointers against NULL and if -fdelete-null-pointer-checks is on, the optimizers would often optimize those away. One way to approach this is stop enabling -fno-delete-null-pointer-checks for the sanitizers and start by replacing all flag_delete_null_pointer_checks with that || ubsan_null_sanitization_active, then argue about if some of those could be reverted one by one.
