RFR: 8328998: Encoding support for Intel APX extended general-purpose registers [v9]

[Steve Dohrmann]

On Tue, 30 Apr 2024 20:22:10 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

> SHA instructions (sha1rnds4, sha1nexte, sha1msg1, sha1msg2, sha256rnds2, sha256msg1, sha256msg2) needs to be encoded using EVEX encoding when egprs are in use.

Thank you, I missed these.  The APX 3.0 spec says xmm register use is limited to 0-15 for SHA instructions. Coincidentally, the new version 4.0 APX spec. also removes support for EVEX promotion of SHA instructions.  Given these specs, I don't think any encoding changes are needed.  I've added an assert to these 7 instructions to check that only registers < 16 are used.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/18476#issuecomment-2088826920