[all-commits] [llvm/llvm-project] dc03ee: [llvm][RISCV] Add RISCV vector tuple type to value...

[Brandon Wu via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: dc03ee3cbba65356de62f2f27fb1934b2731000d
      https://github.com/llvm/llvm-project/commit/dc03ee3cbba65356de62f2f27fb1934b2731000d
  Author: Brandon Wu <brandon.wu at sifive.com>
  Date:   2024-08-31 (Sat, 31 Aug 2024)

  Changed paths:
    M llvm/include/llvm/CodeGen/ValueTypes.h
    M llvm/include/llvm/CodeGen/ValueTypes.td
    M llvm/include/llvm/CodeGenTypes/MachineValueType.h
    M llvm/lib/CodeGen/ValueTypes.cpp
    M llvm/utils/TableGen/Common/CodeGenTarget.cpp
    M llvm/utils/TableGen/VTEmitter.cpp

  Log Message:
  -----------
  [llvm][RISCV] Add RISCV vector tuple type to value types(MVT) (#97993)

Summary:
This patch handles the types(MVT) in `selectionDAG` for RISCV vector
tuples.
As described in previous patch handling llvm types, the MVTs also have
32 variants:
```
riscv_nxv1i8x2, riscv_nxv1i8x3, riscv_nxv1i8x4, riscv_nxv1i8x5, riscv_nxv1i8x6, riscv_nxv1i8x7, riscv_nxv1i8x8,
riscv_nxv2i8x2, riscv_nxv2i8x3, riscv_nxv2i8x4, riscv_nxv2i8x5, riscv_nxv2i8x6, riscv_nxv2i8x7, riscv_nxv2i8x8,
riscv_nxv4i8x2, riscv_nxv4i8x3, riscv_nxv4i8x4, riscv_nxv4i8x5, riscv_nxv4i8x6, riscv_nxv4i8x7, riscv_nxv4i8x8,
riscv_nxv8i8x2, riscv_nxv8i8x3, riscv_nxv8i8x4, riscv_nxv8i8x5, riscv_nxv8i8x6, riscv_nxv8i8x7, riscv_nxv8i8x8,
riscv_nxv16i8x2, riscv_nxv16i8x3, riscv_nxv16i8x4,
riscv_nxv32i8x2.
```

Detail:
An intuitive way to model vector tuple type is using nested scalable
vector, e.g. `nElts=NF, EltTy=nxv2i32`. However it's not compatible to
what we've done to handle scalable vector in TargetLowering, so it would
need more effort to change the code to handle this concept.
Another approach is encoding the `MinNumElts` info in `sz` of `MVT`,
e.g.
`nElts=NF, sz=(NF*MinNumElts*8)`, this makes it much easier to handle
and
changes less code.

This patch adopts the latter approach.

Stacked on https://github.com/llvm/llvm-project/pull/97992



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