[PATCH] D139733: [RISCV] Share reduction lowering code for vp.reduce

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

> First, I remove the ResVT handling, and always use the reduction element type. This appears to be dead code. There's no test coverage, and I think such a construct wouldn't be legal anyways. This is the main reason I posted this for review as I want someone to double check me on this point.

EXTRACT_VECTOR_ELT is allowed to have a scalar result type larger than the element type. BUILD_VECTOR, SPLAT_VECTOR, and INSERT_VECTOR_ELT can have a scalar argument larger than the element type of the vector. This is required by type legalization since the legal scalar types may be larger than the legal vector element types.

I think the VPREDUCE expansion may have been happening during LegalizeDAG when this was written. That would require any scalar types created to be legal. I think it is called during LegalizeVectorOps now and there is a scalar type legalization pass between LegalizeVectorOps and LegalizeDAG.


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  https://reviews.llvm.org/D139733/new/

https://reviews.llvm.org/D139733