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

[Tobias Hartmann]

Nice cleanup! Looks good to me too, assuming this has been tested on a machine that has AVX512F but
not AVX512VL.

Best regards,
Tobias

On 07.02.20 23:37, Viswanathan, Sandhya wrote:
> 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
>