RFR: 8254884: Make sure jvm does not crash with Arm SVE and Vector API

[Vladimir Ivanov]

On Mon, 19 Oct 2020 08:31:38 GMT, Ningsheng Jian <njian at openjdk.org> wrote:

> Currently we have not implemented all Arm SVE code generation for Vector API specific nodes. To make sure hotspot does
> not crash with bad AD file (as NEON has implemented them), we simply add those OPs to unsupported op list.
> This is the port and minor cleanup of JDK-8253211 in repo-panama: https://github.com/openjdk/panama-vector/pull/7 with
> Op_VectorUnbox (not for codegen) and Op_VectorMaskWrapper (actually unused node. dead code?) removed from the
> unsupported op list and Op_VectorLoadConst added.  Test: tier1-3 on AArch64 and x86_64 as well as Vector API tests on
> AArch64 SVE.

Changes requested by vlivanov (Reviewer).

src/hotspot/share/opto/vectorIntrinsics.cpp line 601:

> 599:     int byte_num_elem = num_elem * type2aelembytes(elem_bt);
> 600:     if (!arch_supports_vector(is_store ? Op_StoreVector : Op_LoadVector, byte_num_elem, T_BYTE, VecMaskNotUsed)
> 601:         || !arch_supports_vector(Op_VectorReinterpret, num_elem, T_BYTE, VecMaskNotUsed)) {

s/num_elem/byte_num_elem/ ?

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PR: https://git.openjdk.java.net/jdk/pull/726