On Tue, Feb 26, 2019 at 03:47:30PM +0100, Peter Zijlstra wrote: > On Tue, Feb 26, 2019 at 06:28:45AM -0800, Paul E. McKenney wrote: > > I must confess to not being all that sympathetic to code that takes > > advantage of happenstance stack-frame layout. Is there some reason > > we need that? > > Not that I'm aware; but if it gets this 'obvious' case wrong, I worry > what else it gets wrong. > > At the very least we should get this fixed and compile a kernel with the > fixed compiler to see what (if anything) changes in the generated code > and analyse the changes (if any) to make sure we were ok (or not). > > I mean; yes that example is UB, but the result is also clearly batshit > insane. My understanding is that their goal is better analysis of pointer aliasing, and that this case is a side effect. Thanx, Paul
