[llvm-dev] Immediate operand for vector instructions

[Alex Susu via llvm-dev]

   Hello.
     Tim, indeed the TableGen spec I presented in the previous email has a small error 
related to what you have written - the patter does not allow i64imm. So because of the line:
   list<dag> Pattern = [(int_connex_repeat_x_times i64imm:$imm)];
     I get the following TableGen error:
    <<Unknown leaf kind: i64imm:i64:$imm>>

      But if I correct that error, following also your suggestion, and have the following 
code (reproduced for convenience):
          class REP_1R_DESC_BASE<,
                                      InstrItinClass itin = NoItinerary> {
            dag OutOperandList = (outs);
            /* From include/llvm/Target/Target.td:
               let OperandType = "OPERAND_IMMEDIATE" in {
                 ...
               def i64imm : Operand<i64>; */
            dag InOperandList = (ins i64imm:$imm);

            string AsmString = "REPEAT_X_TIMES($imm";
            list<dag> Pattern = [(int_repeat_x_times i64:$imm)];
            InstrItinClass Itinerary = itin;
          }
          class REP_D_DESC : REP_1R_DESC_BASE;
          class REP_D_ENC :  MSA_I16_FMT<0b101010111>;
          def REP_D: REP_D_ENC, REP_D_DESC;

    We can compile it. Note that this is the only compilable code w.r.t. using i64 or 
i64imm (in the 2 lines above: "dag InOperandList", "list<dag> Pattern").

     However, the problem I was asking help in the previous email still persists: to my 
big surprise (because the property OperandType = "OPERAND_IMMEDIATE" implies that i64imm 
is an immediate operand), the resulting ASM codegen'ed by the instruction selector 
contains a mov and REPEAT_X_TIMES uses a register although I was expecting it to use an 
immediate register:
          mov     r1, 32767               // <MCInst #75 MOV_ri
                                          //  <MCOperand Reg:2>
                                          //  <MCOperand Imm:32767>>
          REPEAT_X_TIMES(r1);
          ...

   Best regards,
     Alex


On 12/5/2016 8:15 PM, Tim Northover wrote:
> On 3 December 2016 at 14:42, Alex Susu via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>>           list<dag> Pattern = [(int_repeat_x_times i64imm:$imm)];
>
> i64imm isn't usable in patterns by default, so what have you really
> written? The operand should probably be "imm:$imm", and "i64:$imm"
> definitely gives the behaviour you're describing.
>
> Cheers.
>
> Tim.
>