[all-commits] [llvm/llvm-project] 408659: [RISCV] Merge GPRPair and GPRF64Pair (#116094)

[Sam Elliott via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 408659c5b5c7d745042ae71db344d1ed10601512
      https://github.com/llvm/llvm-project/commit/408659c5b5c7d745042ae71db344d1ed10601512
  Author: Sam Elliott <quic_aelliott at quicinc.com>
  Date:   2024-11-20 (Wed, 20 Nov 2024)

  Changed paths:
    M llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
    M llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/lib/Target/RISCV/RISCVInstrInfoD.td
    M llvm/lib/Target/RISCV/RISCVRegisterInfo.td
    M llvm/test/CodeGen/RISCV/zdinx-asm-constraint.ll

  Log Message:
  -----------
  [RISCV] Merge GPRPair and GPRF64Pair (#116094)

As suggested by Craig, this tries to merge the two sets of register
classes created in #112983, GPRPair* and GPRF64Pair*.

- I added some explicit annotations to `RISCVInstrInfoD.td` which fixed
the type inference issues I was seeing from tablegen for select
patterns.
- I've had to make the behaviour of `splitValueIntoRegisterParts` and
`joinRegisterPartsIntoValue` cover more cases, because you cannot
bitcast to/from untyped (the bitcast would otherwise have been inserted
automatically by TargetLowering code).
- I apparently didn't need to change `getNumRegisters` again, which
continues to tell me there's a bug in the code for tied inputs. I added
some more test coverage of this case but it didn't seem to help find the
asserts I was finding before - I think the difference is between the
default behaviour for integers which doesn't apply to floats.
- There's still a difference between BuildGPRPair and BuildPairF64 (and
the same for SplitGPRPair and SplitF64). I'm not happy with this, I
think it's quite confusing, as they're very similar, just differing in
whether they give a `untyped` or a `f64`. I haven't really worked out
how the DAGCombiner copes if one meets the other, I know we have some of
this for the f64 variants already, but they're a lot more complex than
the GPRPair variants anyway.



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