[mlir][affine] addLowerOrUpperBound: Disallow pos among boundOperands

[springerm]

Summary

Bounds such as dim_{pos} <= c_1 * dim_x + ... where x == pos are invalid. addLowerOrUpperBound previously added an incorrect inequality to the set. Such cases are now explicitly rejected.

Depends On D105804

[springerm]

fix test

mlir/lib/Analysis/AffineStructures.cpp

FlatAffineConstraints::addLowerOrUpperBound(unsigned pos, AffineMap boundMap,
   for (auto operand : operands) {
     unsigned pos;
     if (!findId(operand, &pos))
       assert(0 && "expected to be found");
     positions.push_back(pos);
   }
 
   for (const auto &flatExpr : flatExprs) {
+    // Invalid bound: pos appears among the operands.
+    if (llvm::find(positions, pos) != positions.end())
+      continue;
+
     SmallVector<int64_t, 4> ineq(getNumCols(), 0);
     ineq[pos] = lower ? 1 : -1;
     // Dims and symbols.
     for (unsigned j = 0, e = map.getNumInputs(); j < e; j++) {
       ineq[positions[j]] = lower ? -flatExpr[j] : flatExpr[j];
     }
     // Copy over the local id coefficients.
     unsigned numLocalIds = flatExpr.size() - 1 - numOperands;