[llvm] [SPIR-V] Handle ASM with multiple outputs (PR #187128)

[Alex Voicu via llvm-commits]

https://github.com/AlexVlx commented:

> This looks fragile. May be gracefully check for assumptions? I've combined the hack I had with your patch, the results looks like this:
> ```
> if (DefReg.isValid() && MRI.hasOneUse(DefReg)) {
> MachineInstr &CopyMI = *MRI.use_instr_begin(DefReg);
> if (CopyMI.getOpcode() == TargetOpcode::COPY) {
>   Register CopyDst = CopyMI.getOperand(0).getReg();
>   if (MRI.hasOneUse(CopyDst)) {
>      MachineInstr &ExtMI = *MRI.use_instr_begin(CopyDst);
>      if (ExtMI.getOpcode() == TargetOpcode::G_TRUNC ||
>          ExtMI.getOpcode() == TargetOpcode::G_ANYEXT) {
>        Register ExtDst = ExtMI.getOperand(0).getReg();
>        AsmCall->getOperand(0).setReg(ExtDst);
>        ExtMI.eraseFromParent();
>        CopyMI.eraseFromParent();
>      }
>    }
>  }
> }
> 
> ``` 

Thank you for the excellent suggestion!

https://github.com/llvm/llvm-project/pull/187128