The document discusses strategies for shortening the feedback loop in software development, emphasizing the importance of timely code testing and correction. It highlights the escalating costs of fixing errors as time progresses and suggests tools like integrated linting and type-time compilation to improve efficiency. Recommendations include frequent code saving and compilation, as well as incorporating linting checks into the development process.

2. xkcd.com

3. 30 recompiles in half a day =
15 %
of time wasted

4. How long do you type
before testing your code?

5. shortening the feedback loop
Philippe Faes, PhD

6. Outline
• The loop design feedback loop
• Time scales: seconds or months?
• Shortening the loop
• What’s next?

7. B.W. Boehm. Software Engineering Economics, 1981
time
cost
cost to fix increases over time

8. B.W. Boehm. Software Engineering Economics, 1981
time
cost
cost to fix increases over time
exponentially
v
log
1
10
100
1000

9. Time scale
• After a few hours when you compile
• Next day by your colleague
• During weekly code review
• Simulation
• After synthesis / P&R
• In “linting” phase before tape out
• After tape-out
• In the field

10. Examples
• After a few seconds?
• After a few minutes?
• Linting phase
• After a few hours by a machine
• Next day by your colleague
• During weekly code review
• Simulation (automatic)
• After synthesis / P&R (automatic)
• In “linting” phase before tape out
• After tape-out

11. compile
simulate
synthesis
(etcetera)
typing
$
$$
$$$

12. save file compile
simulate
synthesis
(etcetera)
typing
$
$$
$$$

13. save file compile
simulate
synthesis
(etcetera)
typing
$
$$
$$$

14. save file compile
simulate
synthesis
(etcetera)
typing
$
$$
$$$
¢¢
¢

15. Regression testing
(not the subject of this talk)

16. Save-time compilation
• Integration with ISim (Xilinx)
ModelSim and Riviera-PRO
• Error markers in the text!
= right where you can fix the code.

17. Save-time linting
• Linting is no longer a separate phase!
• Integrated in development
= much less effort
= cheaper
• Available for Aldec ALINT on request.

18. Type-time compilation
• Compare this to spell check in Word
• BUT: also Grammar, Semantics
• Built in parser
• type-time
• recovering

19. Type-time compilation
• Compare this to spell check in Word
• BUT: also Grammar, Semantics
• Built in parser
• type-time
• recovering

20. Checking in bad code
makes you look bad

21. Examples
• After a few seconds?
• After a few minutes?
• Linting phase
• After a few hours by a machine
• Next day by your colleague
• During weekly code review
• Simulation (automatic)
• After synthesis / P&R (automatic)
• In “linting” phase before tape out
• After tape-out

22. What you can do
• Try out Sigasi Pro at www.sigasi.com
• Save and compile often!
• Integrate linting checks in development
process
• Set up Regression Testing