report_design_area and report_design_area_metric does not match for private designs

[gudeh]

I noticed the area does not match for some private designs, but does for public ones.

Here is a small summary for potential future reference:

• report_metrics is costly and reports multiple things, it also calls report_design_area.
• report_design_area is calculated with RSZ with the function I modified in this PR: Resizer::computeDesignArea(), I understand it is not costly in runtime, and only iterates over block_->getInsts() once.
• OR submodule flow tests in OpenROAD/test/ uses Resizer::computeDesignArea() for reporting metrics.
  • This is why we required test updates in this PR.
• ORFS metrics on the other hand uses another command with a similar name: report_design_area_metrics. It iterates over instances and checks the area directly on a TCL script in OpenROAD/src/Metrics.tcl at these lines with the TCL loop: foreach inst [$block getInsts] {.

Finally, I checked a few designs and the areas reported by the two commands report_design_area and report_design_area_metrics match for pubic designs.

For example, asap7/aes:
OR metric: Design area 1998 um^2 48% utilization.
ORFS metric: [INFO] finish__design__instance__area pass test: 1997.66 <= 2269

This can be easily check by the end of secure-CI report, both are a few lines apart:

Originally posted by @gudeh in #9452 (comment)

[krrish175-byte]

Hi @gudeh, are you working on this issue yourself or can I take it and raise a pr?

[gudeh]

Hi @krrish175-byte, I haven't given too much attention to this yet. Although I am not sure you are able to reproduce the issue, I observed it only on private designs. But feel free to fix it!