[15] RFR (M): 8238680: C2: Remove redundant AD instructions for Replicate nodes

[Viswanathan, Sandhya]

Hi Vladimir,

The patch looks good to me.

Best Regards,
Sandhya

-----Original Message-----
From: Vladimir Ivanov <vladimir.x.ivanov at oracle.com> 
Sent: Friday, February 07, 2020 6:27 AM
To: hotspot compiler <hotspot-compiler-dev at openjdk.java.net>
Cc: Viswanathan, Sandhya <sandhya.viswanathan at intel.com>; Bhateja, Jatin <jatin.bhateja at intel.com>
Subject: [15] RFR (M): 8238680: C2: Remove redundant AD instructions for Replicate nodes

http://cr.openjdk.java.net/~vlivanov/8238680/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8238680

Replicate nodes have special handling on x86 for 512-bit case when AVX-512VL is absent.

But according to Software Developer’s Manual from Intel, EVEX-encoded VPBROADCASTD/VPBROADCASTQ/VBROADCASTSS/VBROADCASTSD only require AVX512F for full 512-bit registers (VL is needed for 128-/256-bit cases), so no special handling is needed.

The patch removes redundant AD instructions (Repl[ILFD]_[reg|mem]_leg) and adjusts generic instructions to handle all cases uniformly.

Testing: tier1-4

Thanks!

Best regards,
Vladimir Ivanov