extract_vector_elt type mismatch?

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1

Hi there,

I’m trying to map extract_vector_elt use the following pattern in tbl file.

Def : Pat <(i64 (extractelt v2i32:$src, 0)), (i64 (SRLIMM GPR:$src, 32))>;

But the tblgen shows :

Type inference contradiction found , forcing v2i32 to have a vector element of type i64

But the manual says this instruction allows return type to be larger than element type.

Anyone can show me any pointers ?

Thanks,
Xiaochu

2

I think this is just intended as a quirk for some weird targets that have a legal vector type, but the scalar type itself is not legal, so it requires an implicit extension when extracting it. I don't think it's intended as something you can arbitrarily do for any vector type, and I wouldn't recommend trying to use it if you don't have to. This probably requires custom selector code

-Matt

3

For some reason EXTRACT_VECTOR_ELEMENT seems to have two TableGen
defs. This should work with "vector_extract" instead of "extractelt"
(despite the deprecation warning, which I don't really understand).

Tim.

4

I think it's a pretty common RISC situation. I notice you deprecated
the mismatching types in r255359, but I don't really see an
alternative after type-legalization with the current nodes. I suppose
we could add ISD::EXTRACT_SEXT_VECTOR_ELEMENT and
ISD::EXTRACT_ZEXT_VECTOR_ELEMENT or something.

Tim.

5

I think that would be an improvement. I manage to break the mismatched element case for most every vector combine I've done

-Matt

6

Thanks all!
vector_extract does the job for me.