To get identical results from compilations in the Quartus® Prime software the following items must be identical for each compilation:
- All design source files including Synopsys Design Constraints (.sdc) files
- Note that changes to comments or naming may cause different compilation results.
- All Quartus Prime project settings
- The version of the Quartus Prime software including patches
- The portion of the design that is preserved with the Rapid recompile option or with incremental compilation partitions
- Note that the db and incremental_db directories must be identical from compilation to compilation to ensure identical results.
- For example, the first compilation after turning on a preservation option may have different results than the previous compilation for portions of the design that are not preserved. Subsequent compilations with no changes will be identical.
- Operating system and CPU
- For example, compiling on Windows OS may give different results than compiling on Linux OS
- Compiling using the 32-bit version of the Quartus II software may give different results than compiling using the 64-bit version.
- Different CPU architectures can have different floating-point implementations.
- Additionally, if you are using the SignalTap II Logic Analyzer, you must select nodes using the SignalTap II: pre-synthesis filter to ensure identical results.
If any of these items are changed, the Fitter starts with a different initial placement for its fitting algorithms that can give different compilation results, programming files and project checksum.
Note: If only Operating System and/or CPUs changes, seed noise will be seen but results will be of similar QOR.