Trying to constrain two results to be of the same type using
`AllTypesMatch` would cause `mlir-tablgen` to crash on this
assertion[1].
Example:
```tblgen
def OpL5 : NS_Op<"op_with_same_but_unconstraint_results",
[AllTypesMatch<["result_a", "result_b"]>]> {
let results = (outs AnyType:$result_a, AnyType:$result_b);
}
```
This is because there was a small bug when constructing the `inferences`
graph from these constraints: The sources should be specified by the
combined arg/result index (in other words, with results negative) not
with the result index.
[1]
99612a3a18/mlir/lib/TableGen/Operator.cpp (L526)
7aebacbee9