Game engine code quality - is everything really that bad

The PVS-Studio team examines typical mistakes that can be encountered in the source code of game engines. The team offers ways to fix the mistakes so that they don't lead to errors (that are sometimes pretty funny) in the gameplay.
The presentation discusses how one can use static analysis to write higher quality code for computer games.
Want more on how a static analyzer can help in game development? Check out our related articles: https://pvs-studio.com/en/blog/posts/?tag=GameDev

Transcript

1. Game Engine Code Quality: Is Everything Really That Bad? George Gribkov pvs-studio.com
2. Unreal Engine 4 2
3. Unreal Engine 4 3
4. Assassins Creed: Unity 4
5. The Witcher 3: Wild Hunt 5
6. The Sims 6
7. BUGS EVERYWHERE 7
8. ▪ Educate developers about common bugs ▪ Use tools to look for bugs automatically How to Avoid Bugs? 8
9. ▪ Show typical error patterns ▪ Show how to use static code analysis correctly This Talk Aims To: 9
10. What Errors in Game Engines Look Like 10
11. Copy-Pasting and the Last Line Effect 11
12. Unreal Engine 4 (C++) 12
13. PVS-Studio warns: V501 There are identical sub-expressions 'Position.Y >= Control.Center.Y — BoxSize.Y * 0.5f' to the left and to the right of the '&&' operator. Unreal Engine 4 (C++) 13
14. Using an Invalid Address 14
15. Amazon Lumberyard (C++) 15
16. PVS-Studio warns: V557 CWE-119 Array overrun is possible. The 'id' index is pointing beyond array bound. Amazon Lumberyard (C++) 16
17. Unreal Engine 4 17
18. Unreal Engine 4 18 PVS-Studio warns: V522 Dereferencing of the null pointer 'LevelStreamingObject' might take place.
19. Evil Thrives in Conditional Expressions 19
20. Unity (C#) 20
21. PVS-Studio warns: V3063 A part of conditional expression is always true if it is evaluated: pageSize <= 1000. Unity (C#) 21
22. Bullet – Red Dead Redemption’s Engine (C++) 22
23. PVS-Studio warns: V709 Suspicious comparison found: 'f0 == f1 == m_fractureBodies.size()’. Remember that 'a == b == c’ is not equal to 'a == b && b == c'. Bullet –Red Dead Redemption’s Engine (C++) 23
24. Operator Precedence 24
25. CryEngine (C++) 25
26. PVS-Studio warns: V502 Perhaps the '?:' operator works in a different way than it was expected. The '?:' operator has a lower priority than the '+' operator. CryEngine (C++) 26
27. Amazon Lumberyard (C++) 27
28. PVS-Studio warns: V502 Perhaps the '?:' operator works in a different way than it was expected. The '?:' operator has a lower priority than the '-' operator. Amazon Lumberyard (C++) 28
29. And Oh-So Many Elusive Typos… 29
30. CryEngine V (C++) 30
31. PVS-Studio warns: V529 Odd semicolon ';' after 'for' operator. CryEngine V (C++) 31
32. Amazon Lumberyard 32
33. PVS-Studio warns: V549 CWE-688 The first argument of 'memcmp' function is equal to the second argument. Amazon Lumberyard 33
34. And Here’s What We Get 34
36. What to Do 36
37. Do Trust the Engines 37 ▪ All these errors are already fixed ▪ Developers actively work on preventing new ones
38. ▪ Unit tests ▪ Code review ▪ Functional, regression testing ▪ Dynamic analysis ▪ Static analysis Fight Bugs 38
39. Static analysis – is an automatic code review procedure. What Is Static Analysis? 39
40. What Is Static Analysis? 40
41. Static Analysis Advantages 41
42. ▪id Software ▪Wargaming ▪Epic Games ▪Playrix ▪Warner Brothers Who Uses Static Analysis… 42 ▪Oculus ▪Codemasters ▪Rocksteady ▪ZeniMax Media ▪And others…
43. Modern Static Analyzers 43 • PVS-Studio • ReSharper • Coverity • SonarQube • Klocwork • Clang Static Analyzer • IntelliJ IDEA • ... • A details list of static analyzers:
44. Analysis: How and Where 44
45. ▪ Locally on developers’ computers (plugins for IDE, compilation monitoring systems) Analysis: How and Where 45
46. ▪ In continuous integration systems (command-line tools, plugins for CI systems, monitoring systems) Analysis: How and Where 46
47. A Typical Scenario 47
48. ▪ Errors are fixed the moment they appear ▪ Many errors are fixed before testing and do not get to that stage ▪ Those that made it are detected at night ▪ The cost to fix bugs is almost zero Recap 48
49. Static Analysis Advantages 49
50. ▪ Of course! Static analysis does not find all bugs ▪ Static analysis – is an answer to the "how else can I improve code quality?" question ▪ An example of a great combination: static + dynamic analysis Should You Use Other Approaches? 50
51. Conclusion 51
52. ▪ Everyone makes mistakes. Even experts. ▪ This is normal, you can use special tools to fix them. Conclusion 52
53. Typical error patterns: ▪ Copy-pasting and the last line effect ▪ Using an incorrect address ▪ Errors in conditional operators ▪ Operation precedence issues ▪ Elusive typos Conclusion 53
54. ▪ You can save a lot of resources, if you set up continuous static analysis Conclusion 54
55. Q&A George Gribkov pvs-studio.com