llvm dev - Aug 2016 - extract_vector_elt type mismatch?

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
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On 08/18/2016 10:24 AM, Xiaochu Liu via llvm-dev wrote:
>
> 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
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

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

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On 18 August 2016 at 10:24, Xiaochu Liu via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Def : Pat <(i64 (extractelt v2i32:$src, 0)), (i64 (SRLIMM GPR:$src,
32))>;
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.

On 18 August 2016 at 10:46, Matt Arsenault via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> 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 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.