Method GetCodegendComputeFnImpl

be/src/exprs/hive-udf-call.cc:546–599

Sample IR for calling the following Java function: public String evaluate(String a, String b, String c) { if (a == null || b == null || c == null) return null; return a + b + c; } To reproduce, create the following function: create function concatenate(string, string, string) returns string location '/test-warehouse/impala-hive-udfs.jar' symbol='org.apache.impala.TestUdf'; then run the followin

///   ret { i64, i8* } %ret
/// }
Status HiveUdfCall::GetCodegendComputeFnImpl(LlvmCodeGen* codegen, llvm::Function** fn) {
   // Cross-compiled functions this hand-crafted function will call.
   llvm::Function* const get_func_ctx_fn =
       codegen->GetFunction(IRFunction::GET_FUNCTION_CTX, false);
   llvm::Function* const get_jni_ctx_fn =
       codegen->GetFunction(IRFunction::GET_JNI_CONTEXT, false);
   llvm::Function* const call_java_fn =
       codegen->GetFunction(IRFunction::HIVE_UDF_CALL_CALL_JAVA, false);

   // Function prototype.
   llvm::LLVMContext& context = codegen->context();
   LlvmBuilder builder(context);

   llvm::Value* args[2];
   llvm::Function* const function =
       CreateIrFunctionPrototype("HiveUdfCall", codegen, &args);

   // Codegen the initialisation of function context etc.
   llvm::BasicBlock* const entry_block =
       llvm::BasicBlock::Create(context, "entry", function);
   builder.SetInsertPoint(entry_block);

   llvm::Value* const fn_ctx = builder.CreateCall(
       get_func_ctx_fn, {args[0], codegen->GetI32Constant(fn_ctx_idx_)}, "fn_ctx");
   llvm::Value* const jni_ctx = builder.CreateCall(get_jni_ctx_fn, {fn_ctx}, "jni_ctx");

   // Codegen the evaluation of children.
   llvm::BasicBlock* const first_eval_child_block =
       llvm::BasicBlock::Create(context, "eval_child", function);
   builder.CreateBr(first_eval_child_block);

   llvm::BasicBlock* call_java_block = nullptr;
   RETURN_IF_ERROR(CodegenEvalChildren(codegen, &builder, function, &args, jni_ctx,
         first_eval_child_block, &call_java_block));

   // Codegen the call to Java and returning the result.
   call_java_block->setName("call_java");
   builder.SetInsertPoint(call_java_block);

   llvm::Value* const ir_type = type().ToIR(codegen);
   llvm::Value* const ir_type_ptr = codegen->GetPtrTo(&builder, ir_type);

   llvm::Value* const ret_ptr = builder.CreateCall(call_java_fn,
       {ir_type_ptr, fn_ctx, jni_ctx}, "ret_ptr");

   llvm::Value* ret_val = CastPtrAndLoad(codegen, &builder, type(), ret_ptr, "ret");
   builder.CreateRet(ret_val);

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

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