SuperWordLoopUnrollAnalysis and loop unrolling

Vladimir Kozlov vladimir.kozlov at
Wed Apr 12 17:56:20 UTC 2017

Try to run debug VM with -XX:+TraceSuperWordLoopUnrollAnalysis.

It could be


On 4/12/17 10:22 AM, Andrew Haley wrote:
> If I set SuperWordLoopUnrollAnalysis=true, then AArch64 C2 stops after
> unrolling a simple loop 4 times.  If I set
> SuperWordLoopUnrollAnalysis=false, it stops after unrolling 16 times.
> Why is is that SuperWordLoopUnrollAnalysis limits unrolling in this
> way?
> The info says
> "Map number of unrolls for main loop via Superword Level Parallelism
> analysis" but that doesn't help me very much.  Only AArch64 and x86
> set this option.
> Thanks,
> Andrew.

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