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To run placement, use the Floorplan and Place Current Cell command
(in menu Tools / Placement).
This selects an appropriate placement algorithm to run.
For more precise control over placement, you can select a particular algorithm in the Placement Preferences (in menu File / Preferences..., "Tools" section, "Placement" tab) and then use the Place Current Cell with Preferred Algorithm command. The Placement Preferences not only lets you select the algorithm, but also lets you set parameters for controlling its operation. |  |
The bottom of the Placement Preferences dialog has controls for all placement operations. These controls set a padding percentage around each placed cell (the default is 0: make the cells touch). You can also ask the placement system to run the Sea of Gates router after placement is done (see Section 9-6-6).
These are the possible placement algorithms:
| Algorithm | Placer | Notes |
| Force Directed | #1 | Gives good results quickly (seconds). Additional time and threads does not improve results |
| #2 | Recommended for highly-symmetric cell layouts (pads, memory), but may be unstable | |
| row/col | Useful for fixed-pitch cells | |
| Genetic | #1 / #2 | Needs long runtime. Additional threads do not help |
| Simulated Annealing | #1 | Not recommended for use |
| #2 | Has best overall results. Useful for non-fixed pitch cells. | |
| row/col | Useful for fixed-pitch cells | |
| Bottom-up partition | Used to break large circuits into subproblems | |
| Bottom-up placement | Fast and good quality for placing random-sized nodes | |
| Min-cut | Simple placer that does not use multiple threads | |
| Simple and Random | Places linearly/randomly: not recommended | |
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