Presentation about getting feedback from your tools faster. Presented at the 2013 PLC2 conference on FPGAs in Stuttgart.

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