https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85720
--- Comment #4 from Mathias Stearn <redbeard0531 at gmail dot com> --- (In reply to Marc Glisse from comment #3) > Again, you are ignoring aliasing issues (just like in your other PR the > function copy isn't equivalent to memmove). Does adding __restrict change > the result? Also, B[i]=B[i]+1 doesn't look like a memset... Sorry, I typoed. It was supposed to be B[i] = A[i] + 1. That still does basically the same thing though: https://godbolt.org/g/dtmU5t. Good point about aliasing though. I guess the right code gen in that case would actually be something that detected the overlap and did the right calls to memset to only set each byte once. Or just do the simple thing: if (b > a && b < a + n) { memset(b, 1, n); memset(a, 0, n); } else { memset(a, 0, n); memset(b, 1, n); } Yes, __restrict helps, but that isn't part of standard c++, and it seems like it never will be.
