RFR: 8304948: [vectorapi] C2 crashes when expanding VectorBox [v2]

[Quan Anh Mai]

On Thu, 20 Apr 2023 03:21:09 GMT, Eric Liu <eliu at openjdk.org> wrote:

>> src/hotspot/share/opto/vector.cpp line 323:
>> 
>>> 321:   if (visited.test_set(vbox->_idx)) {
>>> 322:     assert(vbox->is_Phi(), "not a phi");
>>> 323:     return vbox; // already visited
>> 
>> Shouldn't the short circuit return a transformed node instead? Or it does not matter here? Thanks.
>
> It does not matter. It will finally be transformed in the round, in which it is the root. At this round, it's an input of another Phi.

But that phi will have an incorrect input, because the return value of this call is used as an input of the transformed phi that uses this node?

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PR Review Comment: https://git.openjdk.org/jdk/pull/13489#discussion_r1172049352