Method GetCodegendComputeFnImpl

be/src/exprs/is-not-empty-predicate.cc:80–135

Sample IR output (when child is a SlotRef): define i16 @IsNotEmptyPredicate(%"class.impala::ScalarExprEvaluator"* %eval, %"class.impala::TupleRow"* %row) #37 { entry: %0 = alloca i16 %1 = alloca i16 %coll_val = call { i64, i8* } @GetSlotRef( %"class.impala::ScalarExprEvaluator"* %eval, %"class.impala::TupleRow"* %row) %2 = extractvalue { i64, i8* } %coll_val, 0 %coll_is_null = trunc i64 %2 to i1 b

//   ret i16 1
// }
Status IsNotEmptyPredicate::GetCodegendComputeFnImpl(
    LlvmCodeGen* codegen, llvm::Function** fn) {
  // Create a method with the expected signature.
  llvm::LLVMContext& context = codegen->context();
  llvm::Value* args[2];
  llvm::Function* new_fn =
      CreateIrFunctionPrototype("IsNotEmptyPredicate", codegen, &args);
  llvm::BasicBlock* entry_block = llvm::BasicBlock::Create(context, "entry", new_fn);
  LlvmBuilder builder(entry_block);

  ScalarExpr* child = children_[0]; // The child node, on which to call GetCollectionVal.
  llvm::Function* get_collection_val_fn;
  RETURN_IF_ERROR(child->GetCodegendComputeFn(codegen, false, &get_collection_val_fn));
  DCHECK(get_collection_val_fn != nullptr);

  // Find type for the CollectionVal struct.
  llvm::Type* collection_type = codegen->GetNamedType("struct.impala_udf::CollectionVal");
  DCHECK(collection_type->isStructTy());

  // Construct the call to the evaluation method, and return the result.
  CodegenAnyVal coll_val = CodegenAnyVal::CreateCallWrapped(codegen, &builder,
      child->type(), get_collection_val_fn, args, "coll_val");

  // Find the 'is_null' field of the CollectionVal.
  llvm::Value* is_null = coll_val.GetIsNull("coll_is_null");

  llvm::BasicBlock* check_count =
      llvm::BasicBlock::Create(context, "check_count", new_fn);
  llvm::BasicBlock* ret_null = llvm::BasicBlock::Create(context, "ret_null", new_fn);
  builder.CreateCondBr(is_null, ret_null, check_count);

  // Add code to the block that is executed if is_null was true.
  builder.SetInsertPoint(ret_null);
  // allocate a BooleanVal, set null in it, and return it.
  CodegenAnyVal null_result(
      codegen, &builder, ColumnType(TYPE_BOOLEAN), nullptr, "null_result");
  builder.CreateRet(
      null_result.GetNullVal(codegen, ColumnType(TYPE_BOOLEAN)));

  // Back to the branch where 'is_null' is false.
  builder.SetInsertPoint(check_count);
  // Load the value of 'num_tuples'.
  llvm::Value* num_tuples = coll_val.GetLen();

  llvm::Value* has_values = builder.CreateICmpNE(num_tuples, codegen->GetI32Constant(0));
  CodegenAnyVal has_values_result(
      codegen, &builder, ColumnType(TYPE_BOOLEAN), nullptr, "has_values_result");
  has_values_result.SetVal(has_values);
  builder.CreateRet(has_values_result.GetLoweredValue());

  *fn = codegen->FinalizeFunction(new_fn);
  if (UNLIKELY(*fn == nullptr)) {
    return Status(TErrorCode::IR_VERIFY_FAILED, "IsNotEmptyPredicate");
  }
  return Status::OK();
}

string IsNotEmptyPredicate::DebugString() const {