Method FillCodegendComputeFnNonConstant

be/src/exprs/tuple-is-null-predicate.cc:139–186

Sample IR: define i16 @TupleIsNullPredicate(%"class.impala::ScalarExprEvaluator"* %eval, %"class.impala::TupleRow"* %row) #51 { entry: br label %check_null check_null: ; preds = %entry %tuple_is_null_fn = call i1 @_ZN6impala19TupleRowTupleIsNullEPKNS_8TupleRowEi( %"class.impala::TupleRow"* %row, i32 0) %0 = select i1 %tuple_is_null_fn, i32 1, i32 0 %count = a

///   ret i16 %ret_val
/// }
void TupleIsNullPredicate::FillCodegendComputeFnNonConstant(
    LlvmCodeGen* codegen, llvm::Function* function, llvm::Value* args[2]) const {
  llvm::LLVMContext& context = codegen->context();
  LlvmBuilder builder(context);

  llvm::BasicBlock* entry_block =
      llvm::BasicBlock::Create(context, "entry", function);
  builder.SetInsertPoint(entry_block);

  // Signature:
  // bool TupleRowTupleIsNull(const TupleRow* row, int index);
  // Returns whether row->GetTuple(index) is nullptr.
  llvm::Function* tuple_is_null_fn =
      codegen->GetFunction(IRFunction::TUPLE_ROW_GET_TUPLE_IS_NULL, false);

  llvm::Value* current_count_val = codegen->GetI32Constant(0);
  for (int i = 0; i < tuple_idxs_.size(); i++) {
    // We create the next block that checks whether the next tuple is null and increases
    // 'count' if it is. While the builder's insertion point is still in the previous
    // block we insert a branch to the new block.
    llvm::BasicBlock* check_null_block
        = llvm::BasicBlock::Create(context, "check_null", function);
    builder.CreateBr(check_null_block);

    builder.SetInsertPoint(check_null_block);
    llvm::Value* tuple_is_null = builder.CreateCall(tuple_is_null_fn,
        {args[1], codegen->GetI32Constant(tuple_idxs_[i])}, "tuple_is_null_fn");
    llvm::Value* tuple_is_null_int = builder.CreateSelect(tuple_is_null,
        codegen->GetI32Constant(1), codegen->GetI32Constant(0));
    current_count_val = builder.CreateAdd(current_count_val, tuple_is_null_int, "count");
  }

  // Create the last block that will compare 'count' with the original number of tuples.
  // If they are equal, return a true value, otherwise a false value. While the builder's
  // insertion point is still in the previous block we insert a branch to the new block.
  llvm::BasicBlock* compare_count_block
      = llvm::BasicBlock::Create(context, "compare_count", function);
  builder.CreateBr(compare_count_block);

  builder.SetInsertPoint(compare_count_block);
  llvm::Constant* tuple_ids_size = codegen->GetI32Constant(tuple_ids_.size());
  llvm::Value* cmp =
      builder.CreateICmpEQ(current_count_val, tuple_ids_size, "count_eq_col_num");
  CodegenAnyVal ret_val = CodegenAnyVal::GetNonNullVal(
      codegen, &builder, ColumnType(TYPE_BOOLEAN), "ret_val");
  ret_val.SetVal(cmp);
  builder.CreateRet(ret_val.GetLoweredValue());
}

string TupleIsNullPredicate::DebugString() const {
  stringstream out;