message: Only simplify floor div, ceil div or mod if the rhs constant >= 1.
  Else we hit asserts in MathExtras.
diff: @@ -947,7 +947,7 @@ static AffineExpr simplifyFloorDiv(AffineExpr lhs, AffineExpr rhs) {
  auto lhsConst = lhs.dyn_cast<AffineConstantExpr>();
  auto rhsConst = rhs.dyn_cast<AffineConstantExpr>();
  - if (lhsConst && rhsConst)
  + if (lhsConst && rhsConst && rhsConst.getValue() >= 1)
  return getAffineConstantExpr(
  floorDiv(lhsConst.getValue(), rhsConst.getValue()), lhs.getContext());
  @@ -974,7 +974,7 @@ static AffineExpr simplifyCeilDiv(AffineExpr lhs, AffineExpr rhs) {
  auto lhsConst = lhs.dyn_cast<AffineConstantExpr>();
  auto rhsConst = rhs.dyn_cast<AffineConstantExpr>();
  - if (lhsConst && rhsConst)
  + if (lhsConst && rhsConst && rhsConst.getValue() >= 1)
  return getAffineConstantExpr(
  ceilDiv(lhsConst.getValue(), rhsConst.getValue()), lhs.getContext());
  @@ -1001,7 +1001,7 @@ static AffineExpr simplifyMod(AffineExpr lhs, AffineExpr rhs) {
  auto lhsConst = lhs.dyn_cast<AffineConstantExpr>();
  auto rhsConst = rhs.dyn_cast<AffineConstantExpr>();
  - if (lhsConst && rhsConst)
  + if (lhsConst && rhsConst && rhsConst.getValue() >= 1)
  return getAffineConstantExpr(mod(lhsConst.getValue(), rhsConst.getValue()),
  lhs.getContext());
  