lcb: Problem when reading from the same field with different resources

[kper]

I am working on an extension for aliases to be properly rendered in LLVM.

  register        S : Index -> BitsX  // general purpose register file with stack pointer
  [zero : X(31)]                      // X(31) is the zero register
  [regfile renaming]
  alias register  X = S               // general purpose register file with zero register
  [regfile renaming]
  [half width of : X]
  alias register  W = S

The annotations above indicate the following behavior:

1. If I use resource S then replace it by X
2. If I use resource X and slice it to the half then replace it by W

In the expanded instruction MRS, I write from W(rt) while we also write X(rt). When, I need to

instruction MRS : MoveSystemRegFormat =   if sysreg = SysRegEncode::NZCV then
    X(rt) := (NZCV_N, NZCV_Z, NZCV_C, NZCV_V) as BitsX << 28
  else
    if CurrentEL = 0 then
raise         GeneralException(ExceptionClass::Uncategorized, 0, PC, 0)
    else
match sysreg with
        { SysRegEncode::CurrentEL => X(rt) := CurrentEL as BitsX << 2
        , SysRegEncode::SPSel => X(rt) := SPSel as BitsX
        , SysRegEncode::ESR_EL1 => X(rt) := ESR_EL1
        , SysRegEncode::SPSR_EL1 => X(rt) := SPSR_EL1
        , SysRegEncode::SP_EL0 => if SPSel = 0 then
raise     GeneralException(ExceptionClass::Uncategorized, 0, PC, 0)
else
  X(rt) := SP_EL0
        , SysRegEncode::SP_EL1 => if SPSel = 0 then
raise     GeneralException(ExceptionClass::Uncategorized, 0, PC, 0)
else
  let sp = SP in
    {
      SP_EL1 := sp
      X(rt) := sp
    }
        , SysRegEncode::ELR_EL1 => X(rt) := ELR_EL1
        , SysRegEncode::VBAR_EL1 => X(rt) := VBAR_EL1
        , _ => raise   GeneralException(ExceptionClass::Uncategorized, 0, PC, 0)
        }

def MRS : Instruction
{
let Namespace = "aarch64temp";

let Size = 4;
let CodeSize = 4;

let OutOperandList = ( outs X:$rt, W:$rt );
let InOperandList = ( ins AArch64Base_MRS_sysregAsInt64:$sysreg );

The let OutOperandList = ( outs X:$rt, W:$rt ); is not compilable.

[AndreasKrall]

First of all we will not introduce the new annotation regfile renaming as it is completely covered by the keyword alias which also contains the information which register is renamed by another one. renaming should be reserved for the MiA for special rename registers.

For the other stuff we need some discussion in the meeting.