[jdk18] RFR: 8278948: compiler/vectorapi/reshape/TestVectorCastAVX1.java crashes in assembler [v2]

[Vladimir Kozlov]

On Thu, 23 Dec 2021 11:37:06 GMT, Quan Anh Mai <duke at openjdk.java.net> wrote:

>> x86 docs say that `vcvtdq2ps` is AVX1 instruction:
>> ![image](https://user-images.githubusercontent.com/5215794/147149423-10988f8d-9bcd-41ca-b728-bc2c34e3bd35.png)
>
> Hi, while the instruction is supported in hardware, the VM does not support the vector shape. As a result, there should not be a situation where we have a vector node with that shape on AVX1. Thank you very much.

Why do you think that? What about this code when length is the same (and UseAVX could be 1):
https://github.com/openjdk/jdk18/blob/master/src/hotspot/cpu/x86/x86.ad#L7069

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PR: https://git.openjdk.java.net/jdk18/pull/46