[Bug sanitizer/81387] UBSAN consumes too much memory at -O2

["babokin at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81387

--- Comment #3 from Dmitry Babokin <babokin at gmail dot com> ---
Interesting that you've mentioned -fno-sanitize-recover, I haven't realized
that it has effect on the number of basic blocks. But by default I run
"-fsanitize=undefined -fno-sanitize-recover=undefined", so the numbers that I
posted are for this combination (-fno-sanitize-recover=all is effectively the
same). I've tried without -fno-sanitize-recover=undefined and it is:
-O2 -fsanitize=undefined: 358s, 62Gb
-O1 -fsanitize=undefined: 280s, 2.7Gb

Also clang trunk:
-O2 -fsanitize=undefined: 173s, 1.5Gb
-O2 -fsanitize=undefined -fno-sanitize-recover=undefined: 224s, 1.8Gb

I understand that the reasons for consuming more memory with UBSAN enabled are
quite fundamental, but looking at such an extreme increase may uncover problems
when algorithms consume more that they supposed to.

Again, I'm not insisting on fixing it, I'm rather drawing attention to
suspicious behaviour, which you may consider worth looking at.