[GPL] Add randomized initial placement perturbation in GPL#10642
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| // microns. We guarantee at least 1 site/row step of shift if perturbation is | ||
| // enabled. |
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Why is that guarantee needed? Global placement doesn't legal the result.
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It's not needed, you want to simplify to something else?
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We could use https://www.boost.org/doc/libs/latest/libs/math/doc/html/math_toolkit/dist_ref/dists/normal_dist.html with a <good value> radius if you'd prefer.
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Signed-off-by: Drew Lewis <cannada@google.com> TAG=agy CONV=0fed8794-10c3-4c6f-bdf2-3dedf6c02c30
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Summary
Implemented a randomized initial placement perturbation feature in the OpenROAD Global Placer (GPL). This feature shifts standard cells by discrete increments of site widths (X direction) and row heights (Y direction), bounded to a maximum of 0.5 microns in both directions.
This replacement of the legacy
srand(42)andrand()non-grid-aligned cell perturbation is controlled by a seed configured via the new-random_seedflag (default is1)Impact
-random_seedoption to theglobal_placementTcl command to customize the random seed (default is1)..okand.defokfiles) to align with the new default seed1layout expectations.Verification
./etc/Build.sh).