[LLVMdev] ARM vectorizer cost model

Renato Golin Linaro renato.golin at linaro.org
Fri Jan 11 07:36:09 PST 2013

On 10 January 2013 23:00, Nadav Rotem <nrotem at apple.com> wrote:

> Some of the costs for the arithmetic operations should be handled
> automatically by the BasicTTI (which asks TartetLowering if the type and
> operations are legal). We need to have cost tables for things like "trunk
> <4 x i64> to <4 x i8>" because even TLI does not know how custom operations
> gets lowered.

BasicTTI::getCastInstrCost() assumes that they're free, which is probably
so that it returns something that doesn't break the cost model.

I can see the X86 table in X86TTI::getCastInstrCost(), are you expecting
something similar? I shall investigate all possible combinations and try to
build a similar model.

That also means we should re-using the X86TypeConversionCostTblEntry as a
more generic structure?

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