Can't build BPF clone target b/c of int_bpf_pseudo

RobertRogers · February 11, 2022, 10:03pm

I’m learning about LLVM backend generation. I’ve cloned Target/BPF and called it Target/Dummy, renamed everything suitably, set up cmake files etc. I’m having trouble with

 int_dummy_pseudo

which corresponds to BPF’s

 int_bpf_pseudo

which occurs only twice, in

github.com

llvm/llvm-project/blob/main/llvm/include/llvm/IR/IntrinsicsBPF.td#L21-L22


      
          def int_bpf_pseudo : ClangBuiltin<"__builtin_bpf_pseudo">,
                      Intrinsic<[llvm_i64_ty], [llvm_i64_ty, llvm_i64_ty]>;

github.com

llvm/llvm-project/blob/main/llvm/lib/Target/BPF/BPFInstrInfo.td#L382


      
            let Inst{55-52} = 2;
            let Inst{47-32} = 0;
            let Inst{31-0} = 0;
            let BPFClass = BPF_LD;
            bit isPseudo = true;
          }
          
          
def LD_pseudo
              : TYPE_LD_ST<BPF_IMM.Value, BPF_DW.Value,
                           (outs GPR:$dst),
                           (ins i64imm:$pseudo, u64imm:$imm),
                           "ld_pseudo\t$dst, $pseudo, $imm",
                           [(set GPR:$dst, (int_bpf_pseudo imm:$pseudo, imm:$imm))]> {
          
          
  bits<4> dst;
            bits<64> imm;
            bits<4> pseudo;
          
          
  let Inst{51-48} = dst;
            let Inst{55-52} = pseudo;
            let Inst{47-32} = 0;

This builds fine for BPF, but not for my clone. It fails when the build file tries to do

 tablegen -gen-dag-isel

on Dummy.td (which corresponds to BPF.td).

RobertRogers · February 12, 2022, 9:31am

UPDATE: Problem solved. My newly created intrinsics file needs to be registered in llvm-project/Intrinsics.td at main · llvm/llvm-project · GitHub