RFR(M) 8180823: [s390] Rework/optimize AES intrinsics

[Doerr, Martin]

Hi Lutz,

nice change. Thanks for also fixing the stack pointer update order (missing part of 8180659). I didn’t find real bugs, but I’d like to get at least some comments fixed.


·         The comment in front of generate_push_Block mentions a “JIT_TIMER” timer which you didn’t contribute.

·         The comments describing the stack layout claim that there were requirements “min. size AES_parmBlk_addspace” and “Z_SP after expansion, octoword-aligned”. I think neither the minimal size nor the octoword alignment of the SP are required, so please remove these comments if this is correct. I believe that only the parmBlk needs the alignment.

·         The stack reservation is a little oversized. Maximum space used by alignment is AES_parmBlk_align-8. Please fix at least the comment. The spill space is also oversized (only 2 slots are used). I leave it up to you if you want to reduce stack space reservation. As this frame is only on top while processing AES stuff, it’s not really an issue to waste a few bytes.

·         generate_AES_cipherBlock contains an unnecessary rotate_then_insert instruction which seems to be a leftover from some removed functionality.

I can also sponsor this change after we go a 2nd review.

Best regards,
Martin


From: hotspot-compiler-dev [mailto:hotspot-compiler-dev-bounces at openjdk.java.net] On Behalf Of Schmidt, Lutz
Sent: Freitag, 28. Juli 2017 13:06
To: hotspot-compiler-dev at openjdk.java.net
Subject: RFR(M) 8180823: [s390] Rework/optimize AES intrinsics

Dear all,

I would like to request reviews for this s390-only enhancement:
Bug:    https://bugs.openjdk.java.net/browse/JDK-8180823
Webrev: http://cr.openjdk.java.net/~lucy/webrevs/8180823.00/

The code for AES intrinsics in stubGenerator_s390.cpp is reworked to get rid of multiple copies of basically the same code snippets. Some chances for minor performance improvements are also taken advantage of.

The code has been active locally @SAP for several weeks now. No problems popped up.

Thank you!
Lutz


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