On Thu, Dec 2, 2010 at 2:20 PM, Joe Buck <joe.b...@synopsys.com> wrote: > On Wed, Dec 01, 2010 at 10:26:58PM -0800, Florian Weimer wrote: >> * Chris Lattner: >> >> > On overflow it just forces the size passed in to operator new to >> > -1ULL, which throws bad_alloc. >> >> This is also what my patch tries to implement. > > Yes, but Chris's code just checks the overflow of the multiply. Your > patch achieves the same result in a more complex way, by > computing the largest non-overflowing value of n in > > new T[n]; > > and comparing n against that. Even though max_size_t/sizeof T is a > compile-time constant, this is still more expensive.
I would expect max_size_t/sizeof(T) to be actually an integer constant that n is compared against. I would be surprised if that one-time comparison is noticeable in real applications that new an array of objects. > >
