Call to getCastInstrCost(): types

[Jonas Paulsson via llvm-commits]

Hi Matthew,

your commit "[LV] Update type in cost model for scalarization" triggered 
an assert in the SystemZ backend. It checks that if the source type is a 
vector type, the result should also be a vector type.

SystemZTTIImpl::getCastInstrCost() was called with a query of 'zext <2 x 
i32> to i64', which doesn't make sense, I think...

To fix this, I reused what you did in getArithmeticInstrCost() in 
LoopVectorize.cpp with the call to getCastInstrCost(). Does this look 
right to you?

About multiplying with "N *": I see no scalarization overhead included 
here. Is this intended, or is there an improvement planned on this more 
generally?

Also, I have not checked if this is missing in more places, but this is 
the only case I have run into.

/Jonas

PS The assert that triggered is one that I added based on general 
intuition, and how these methods are called currently. Not sure if I 
should exclude bitcast from this? That might be still correct, but I 
don't think it is used that way at least currently...


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