6D Router Lookahead #2445
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6D Router Lookahead #2445
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…_lookahead with this new dim
…uting_cost_map to have 3 dim
… from_layer_num and to_layer_num
…layers and store all info in a single map
… it regardless of being cube_Bb
…is used in both cases
…rilog-to-routing into 6d_router_lookahead
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Titan QoR: |
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Slight 1.6% router time increase, but since place time is up .5% and pack time 1.9% this is hopefully machine load noise. In any case we need it so merging, and Amin is working on optimization of the overall lookahead size and compute time for the future (beyond this PR). |
vaughnbetz
approved these changes
Nov 23, 2023
| */ | ||
| std::pair<t_src_opin_delays, t_src_opin_inter_layer_delays> compute_router_src_opin_lookahead(bool is_flat); | ||
| t_src_opin_delays compute_router_src_opin_lookahead(bool is_flat); |
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Should probably just get this from the router context, but your call.
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We don't have it in the router context yet.
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@vaughnbetz This PR is ready to merge |
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In this pull request, the main data structure of the router lookahead is updated to have six dimensions instead of five. The previous dimensions were: [dest. layer][chanx/y][seg_type][width][height].
The new dimensions are: [source layer][chanx/y][seg_type][dest. layer][width][height].
Previously, since the connections were only from OPINs, each layer had a separate router lookahead. In the case of die crossing, the minimum delay of the inter-layer connection was stored and added to the cost to reach the sink on the destination layer from that point.
As development progresses in adding inter-die connections, we needed to update the router lookahead to consider that connections can cross die on switch blocks. To achieve this, an additional dimension is added to the array. Therefore, the first index related to the layer is now the source layer, and the second index related to the layer pertains to the layer on which the sink is located.