[llvm-dev] getScalarizationOverhead()

[Hal Finkel via llvm-dev]

On 01/20/2017 06:11 AM, Jonas Paulsson via llvm-dev wrote:
> Hi,
>
> I wonder why getScalarizationOverhead() does not take into account the 
> number of operands of the instruction? This should influence the 
> number of extracts needed, so instead of
>
> Scalarization cost = NumEls * (insert + extract)
>
> it would be better to do
>
> Scalarization cost = NumEls * (insert + (extract * numOperands))

I suspect this is an oversight (although we need to be a bit careful 
here because if two operands are the same, which is not uncommon, we 
don't want to double the cost).

  -Hal

>
>
> / Jonas
>
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-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory