RFR: 8265956: JVM crashes when matching LShiftVB Node [v2]

[Xiaohong Gong]

On Wed, 28 Apr 2021 09:52:22 GMT, Wang Huang <whuang at openjdk.org> wrote:

>> It is fount that the rule `match(Set dst (LShiftVB src shift))` is missing on many cpus, such like `aarch64` and `x86`. It is this reason that JVM will crash under `JDK-8265956`'s test case. In this commit, I :
>> * show the crash case `TestVectorShuffleIotaShort`
>> * solve the issue on `aarch64` and `x86` by adding the rule. 
>> * test after fixing on tire1~3
>> 
>> Thank you for your review. Any suggestion is welcome. 
>>                          Wang Huang
>
> Wang Huang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   add m4 file

src/hotspot/cpu/aarch64/aarch64_neon.ad line 5292:

> 5290:             n->as_Vector()->length() == 8);
> 5291:   match(Set dst (LShiftVB src (LShiftCntV shift)));
> 5292:   match(Set dst (LShiftVB src shift));

Does it make sense if changing the mid-end codes to make sure the immediate shift is broadcasted to a vector?

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