[Bug tree-optimization/96783] New: [11 Regression] std::rotate miscompiled

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96783

            Bug ID: 96783
           Summary: [11 Regression] std::rotate miscompiled
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
                CC: rguenth at gcc dot gnu.org
  Target Milestone: ---

This is miscompiled at -O3 since r11-1897 and dies with a segfault:

#include <vector>
#include <algorithm>
#include <iostream>

int main()
{
  std::vector<std::vector<int>> c{{1,2}, {3,4}, {5,6}, {7,8}, {9,10}};

  std::rotate(c.begin(), c.begin() + 3, c.end());

  for (auto v : c)
  {
    for (auto i : v)
      std::cout << i << ' ';
    std::cout << '\n';
  }
  std::cout << '\n';

  std::vector<std::vector<int>> c2{{7,8}, {9,10}, {1,2}, {3,4}, {5,6}};

  if (c != c2)
    throw 1;
}