[llvm] [AMDGPU] Replace tablegen field is_gfx940_xdl with is_sgemm. NFC. (PR #143865)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

> I'm not sure if this patch makes sense. I'd really appreciate any comments.
> 
> My understanding is:
> 
>     * before gfx942, "XDL" means MFMA_*_F16/BF16/F32/I8 (i.e. everything except F64)
> 
>     * from gfx942, "XDL" means MFMA_*_F16/BF16/XF32/I8 (i.e. everything except F32 and F64)

Right, the meaning of XDL was changing between subtargets, so it is very hard to make it clean.

> But maybe this is not accurate? The way `is_sgemm` is defined does not seem to match this description, e.g. some `_f32` instructions are included but other ones are not.

This is probably the reason I would not do it this way, because some _f32 instructions are not sgemm in these terms.

https://github.com/llvm/llvm-project/pull/143865