How can you test a code generator for a new target architecture?

1 Define the test objectives

The first step to test a code generator is to define the test objectives, which are the criteria that determine the quality and correctness of the code generation. These objectives include functional correctness, performance, compatibility, and robustness. Functional correctness means that the generated code should produce the same output as the source program for any valid input. Performance requires that the generated code should run as fast as possible and use as little resources as possible on the target architecture. Compatibility entails that the generated code should comply with the standards and conventions of the target architecture and operating system. Finally, robustness suggests that the generated code should handle errors and exceptions gracefully and avoid undefined behavior.

2 Design the test cases

Testing a code generator requires designing test cases that are the inputs and outputs to exercise the code generator. These cases should cover all of its features and functionalities, such as data types and structures, control flow and logic, operators and expressions, and system calls and libraries. Specifically, the test cases should include different kinds of data types and structures (e.g. integers, floats, strings, arrays, pointers, structs, unions), control flow and logic (e.g. loops, branches, functions, recursion), operators and expressions (e.g. arithmetic, bitwise, logical, relational, assignment), as well as system calls and libraries (e.g. input/output, memory management, file system, networking).

3 Implement the test cases

The third step to test a code generator is to implement the test cases, which are the source programs that provide the inputs and outputs for the code generator. When writing these test cases, they should be written in a high-level language that can be compiled by the code generator, such as C or Java. Additionally, they should have a clear and consistent format. This includes a comment that describes the purpose and expected outcome of the test case, a header that includes the necessary libraries and declarations, a main function that contains the input and output statements, and a return 0 statement that indicates successful completion of the test case.

4 Run the test cases

The fourth step to test a code generator is to run the test cases, which are the commands that execute the code generator and the generated code. These tests should be conducted on the target architecture or a simulator that mimics its behavior. To compare the actual output with the expected output, you should consider using a script that automates the compilation and execution of the test cases and checks the output against a reference file. Additionally, a debugger can be utilized to inspect and modify the generated code and program state, while a profiler can measure the performance and resource usage of the generated code and program.

5 Analyze the test results

The fifth step to test a code generator is to analyze the test results, which are the data and feedback that indicate the success and failure of the test cases. The test results should be evaluated according to the test objectives and the test cases, such as producing a report summarizing the number and percentage of passed and failed test cases with reasons for any failures, creating a log that records the details and errors of each test case and the generated code, and plotting a graph that shows the performance and resource usage of the generated code and program against different parameters and benchmarks.

6 Improve the code generator

The sixth and final step to test a code generator is to improve it. This involves actions and modifications that enhance the quality and correctness of the code generation. The code generator should be improved based on the test results and the test objectives, such as bug fixes to correct mistakes or flaws, feature additions to implement new or missing functionality, and refactors to restructure or simplify the code generator. These measures will make it easier to understand, maintain, and extend.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?