Hierarchical Reuse Reporting - 2023.2 English

The -hierarchical option displays a breakdown of cell reuse at each hierarchical level. Following is an example of report_incremental_reuse -hierarchical:

The reuse status of each cell is reported, beginning with the top-level hierarchy, then covering each level hierarchy contained within that level. The report progresses to the lowest level of hierarchy contained within the first submodule, then moves on to the next one.

In this example, the top level cell is mb_preset_wrapper with a cumulative reuse total of 5339 cells with 0 new cells. The row with mb_preset_wrapper in parentheses shows the cell reuse status contained within mb_preset_wrapper and but not its submodules. Of the 5339 cells, only 37 are within mp_preset_wrapper and the remainder are within its submodules.

There are five columns indicating cell reuse status at each level, although only the first one Discarded(Illegal) is shown. These columns have footnote references in the report with further reasons for discarding reused placement.

* Discarded illegal placement due to netlist changes

** Discarded to improve timing

*** Discarded placement by user

**** Discarded due to its control set source is unguided

***** Discarded due to its connectivity has Loc Fixed Insts

Instead of reporting all hierarchical levels, you can use the -hierarchical_depth option to limit the number of submodules to an exact number of levels. The following is the previous example, adding -hierarchical_depth of 1:

report_incremental_reuse -hierarchical -hierarchical_depth 1

This limits reporting to the top level mb_preset_wrapper. If you had used a -hierarchical_depth of 2, the top and each level of hierarchy contained within mb_preset_wrapper would be reported, but nothing below those hierarchical cells.