Method CodegenHashRow

be/src/runtime/krpc-data-stream-sender.cc:953–1034

An example of generated code. Used the following query to generate it: use functional_orc_def; select a.outer_struct, b.small_struct from complextypes_nested_structs a full outer join complextypes_structs b on b.small_struct.i = a.outer_struct.inner_struct2.i + 19091; define i64 @KrpcDataStreamSenderHashRow(%"class.impala::KrpcDataStreamSender"* %this, %"class.impala::TupleRow"* %row, i64 %seed)

//   ret i64 %hash_val
// }
Status KrpcDataStreamSenderConfig::CodegenHashRow(
    LlvmCodeGen* codegen, llvm::Function** fn) {
  llvm::LLVMContext& context = codegen->context();
  LlvmBuilder builder(context);

  LlvmCodeGen::FnPrototype prototype(
      codegen, "KrpcDataStreamSenderHashRow", codegen->i64_type());
  prototype.AddArgument(LlvmCodeGen::NamedVariable(
      "this", codegen->GetNamedPtrType(KrpcDataStreamSender::LLVM_CLASS_NAME)));
  prototype.AddArgument(
      LlvmCodeGen::NamedVariable("row", codegen->GetStructPtrType<TupleRow>()));
  prototype.AddArgument(LlvmCodeGen::NamedVariable("seed", codegen->i64_type()));

  llvm::Value* args[3];
  llvm::Function* hash_row_fn = prototype.GeneratePrototype(&builder, args);
  llvm::Value* this_arg = args[0];
  llvm::Value* row_arg = args[1];

  // Store the initial seed to hash_val
  llvm::Value* hash_val = args[2];

  // Unroll the loop and codegen each of the partition expressions
  for (int i = 0; i < partition_exprs_.size(); ++i) {
    llvm::Function* compute_fn;
    RETURN_IF_ERROR(
        partition_exprs_[i]->GetCodegendComputeFn(codegen, false, &compute_fn));

    // Load the expression evaluator for the i-th partition expression
    llvm::Function* get_expr_eval_fn =
        codegen->GetFunction(IRFunction::KRPC_DSS_GET_PART_EXPR_EVAL, false);
    DCHECK(get_expr_eval_fn != nullptr);
    llvm::Value* expr_eval_arg =
        builder.CreateCall(get_expr_eval_fn, {this_arg, codegen->GetI32Constant(i)});

    // Compute the value against the i-th partition expression
    llvm::Value* compute_fn_args[] = {expr_eval_arg, row_arg};
    CodegenAnyVal partition_val = CodegenAnyVal::CreateCallWrapped(codegen, &builder,
        partition_exprs_[i]->type(), compute_fn, compute_fn_args, "partition_val");

    CodegenAnyValReadWriteInfo rwi = partition_val.ToReadWriteInfo();
    rwi.entry_block().BranchTo(&builder);

    llvm::BasicBlock* hash_val_block =
        llvm::BasicBlock::Create(context, "hash_val_block", hash_row_fn);

    // Set the pointer to NULL in case 'partition_val' evaluates to NULL
    builder.SetInsertPoint(rwi.null_block());
    llvm::Value* null_ptr = codegen->null_ptr_value();
    builder.CreateBr(hash_val_block);

    // Saves 'partition_val' on the stack and passes a pointer to it to the hash function
    builder.SetInsertPoint(rwi.non_null_block());
    llvm::Value* native_ptr = SlotDescriptor::CodegenStoreNonNullAnyValToNewAlloca(rwi);
    native_ptr = builder.CreatePointerCast(native_ptr, codegen->ptr_type(), "native_ptr");
    builder.CreateBr(hash_val_block);

    // Picks the input value to hash function
    builder.SetInsertPoint(hash_val_block);