https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78655
Andrew Macleod <amacleod at redhat dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |amacleod at redhat dot com --- Comment #9 from Andrew Macleod <amacleod at redhat dot com> --- Created attachment 49556 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49556&action=edit testcase (In reply to Marc Glisse from comment #8) > (just to put this somewhere) > We have multiple ways of doing pointer arithmetic in gcc. After the recent > patch, we know that g returns nonnull, but we don't know it for f. > > struct A{int a,b;}; > int*f(A*p){return&p->b;} > int*g(A*p){return(int*)p+1;} I tweaked this and made a testcase out of it. I think it is correct? We do know that both f and g are non-null now, as well as checks for when returning p->a for 0 offsets... So I think this is covered? Furthermore, bool f(int* a) { bool x = a == nullptr; a += 10; return x; } turns into a_1(D) int * VARYING <bb 2> : x_2 = a_1(D) == 0B; a_3 = a_1(D) + 40; return x_2; a_3 : int * [1B, +INF] And from there, I don't see any way to determine that 'a_1' can't be nullptr. we've lost whatever context nullptr is suppose to provide... its just a 0 now. All we can see is that a_3 is non-null.