RFR: 8265907: JVM crashes when matching VectorMaskCmp Node for Neon backend

[Ningsheng Jian]

On Sun, 25 Apr 2021 07:38:30 GMT, Wang Huang <whuang at openjdk.org> wrote:

> * fix the issue JDK-8265907

src/hotspot/cpu/aarch64/aarch64.ad line 2421:

> 2419:         return false;
> 2420:       }
> 2421:       break;

Hmm, currently min_vector_size for byte type is lower to 4 bytes to support vector api shuffle, but we don't have a per Opcode size check correctly. E.g. no length check for reduce_add8B, do you also see any issue for that? I think we'd better only allow 4 bytes for vector api shuffle related opcodes (and 2 for mask related opcodes) in match_rule_supported_vector, while for other opcodes, we still only support for >=64 bits.

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PR: https://git.openjdk.java.net/jdk/pull/3670