placeDesign uses trialRoute

Hi!

I'm using the Foundation Flows of Encounter v08.10 for a flat design. I found that running the step "place" uses the command "placeDesign". When run interactively, this command uses trial route before doing the placement, while when run from the script, it doesn't. No wires are routed because no cells are placed, but it still does something.

To find the reason I compared the settings in both cases with getUsefulSkewMode, getAnalysisMode, getExtractRCMode, getOptMode, getScanReorderMode, and getTrialRouteMode. After setting the very same options in the interactive run, it still used to run trial route before the placement.

Could you please give me a hint what options case the usage of trial route before the placement? And what are the pros and cons for it?

Additinally I found quite large differences in the placement for my test design (a simple 16 bit up/down counter). When doing placement by the script, Encounter puts all D-FF at the two bottom rows of the core and all combinational gates in the rows above. When doing the placement in the interactive run (with identical options of the above modes) the D-FF are spread across the whole core area. Could this be caused by the preceding trial route? Or what else could cause this?

Thanks

  Johann Glaser