[PATCH] D119529: [BasicTTI] Set scalarization cost of getCommonMaskedMemoryOpCost to Invalid.

[Liao Chunyu via Phabricator via llvm-commits]

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> This function assumes fixed-width vectors and cannot be used for scalable vectors. I'm not sure what returning 'Invalid' here would really fix, other than the compiler not crashing for a use-case that should not have occurred in the first place, because an overloaded cost function should have been implemented. Whether the compiler falls into the assert from `cast<FixedVectorType>`, or whether it returns an Invalid cost, in either case you'll need to implement a memory-op-cost function for your target. And because you'll need to implement a cost-function anyway, returning Invalid doesn't really make a difference, because then this code will never be hit. Otherwise, you would have been able to write a test-case for it.

Many salable vectors use this function and crash . Maybe D121677 <https://reviews.llvm.org/D121677> is a test-case.  GetMaskedMemoryOpCost and getGatherScatterOpCost only return  getCommonMaskedMemoryOpCost , so each scalable vector call to these functions will crash. However, getMaskedMemoryOpCost and getGatherScatterOpCost can be implemented  by each target, not implemented will it crashes.  There seems to be a problem.


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https://reviews.llvm.org/D119529