RFR: 8265956: JVM crashes when matching LShiftVB Node [v3]

[Wang Huang]

On Sat, 8 May 2021 03:52:58 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> Wang Huang has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix bugs
>
> src/hotspot/share/opto/vectorIntrinsics.cpp line 372:
> 
>> 370:   } else if (step_val->get_con() > 1) {
>> 371:     Node* cnt = gvn().makecon(TypeInt::make(log2i_exact(step_val->get_con())));
>> 372:     Node* shift_cnt = gvn().transform(new LShiftCntVNode(cnt, vt));
> 
> Use "vector_shift_count"?  It will mask the shift count before generating the `LShiftCntVNode`.

`vector_shift_count` which calls `VectorNode::shift_count` does not contain `Op_LShiftB`:

```c++
VectorNode* VectorNode::shift_count(int opc, Node* cnt, uint vlen, BasicType bt) {
  // Match shift count type with shift vector type.
  const TypeVect* vt = TypeVect::make(bt, vlen);
  switch (opc) {
  case Op_LShiftI:
  case Op_LShiftL:
    return new LShiftCntVNode(cnt, vt);
  case Op_RShiftI:
  case Op_RShiftL:
  case Op_URShiftB:
  case Op_URShiftS:
  case Op_URShiftI:
  case Op_URShiftL:
    return new RShiftCntVNode(cnt, vt);
  default:
    fatal("Missed vector creation for '%s'", NodeClassNames[opc]);
    return NULL;
  }
}

-------------

PR: https://git.openjdk.java.net/jdk/pull/3747