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rsz: prevent high fanout nets from allocating permanent massive map - #11865
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Signed-off-by: Mike Inouye <mikeinouye@google.com>
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This pull request optimizes the Rebuffer::setPin method in src/rsz/src/Rebuffer.cc by preventing performance degradation during cache clearing. Instead of always calling clear() on buffer_delay_cache_, which can become slow if the bucket count grows too large, the code now checks if the bucket count exceeds a threshold of 256. If it does, the cache is reinitialized to release the large bucket arrays and maintain O(1) complexity across nets. There are no review comments, and we have no additional feedback to provide.
jhkim-pii
approved these changes
Oct 20, 2026
jhkim-pii
enabled auto-merge
October 20, 2026 17:34
jhkim-pii
merged commit Oct 20, 2026
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Thank you for the quick review Jaehyun! |
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No problem. Thank you for the fix! |
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Summary
During
global_placement -timing_driven, a single high fanout net causesbuffer_delay_cache_to rehash to a large bucket count. The size is never reset, so every subsequent driver pin infullyRebuffer()(hundreds of thousands of small 1–2 sink nets) pays a massive memset cost for the map.Type of Change
Impact
Prevents hanging in
global_placement -timing_drivenobserved after #11798.Verification
./etc/Build.sh).Related Issues
#11798.