Merge pull request #2949 from AlexandreSinger/feature-ap-solver

[AP][GlobalPlacment] Added Bound2Bound Solver

Author: AlexandreSinger

doc/src/vpr/command_line_usage.rst

@@ -1195,15 +1195,43 @@ Analytical Placement is generally split into three stages:
 
     Analytical Placement is experimental and under active development.
 
-.. option:: --ap_global_placer {quadratic-bipartitioning-lookahead | quadratic-flowbased-lookahead}
+.. option:: --ap_analytical_solver {qp-hybrid | lp-b2b}
 
-    Controls which Global Placer to use in the AP Flow.
+    Controls which Analytical Solver the Global Placer will use in the AP Flow.
+    The Analytical Solver solves for a placement which optimizes some objective
+    function, ignorant of the FPGA legality constraints. This provides a "lower-
+    bound" solution. The Global Placer will legalize this solution and feed it
+    back to the analytical solver to make its solution more legal.
 
-    * ``quadratic-bipartitioning-lookahead`` Use a Global Placer which uses a quadratic solver and a bi-partitioning lookahead legalizer. Anchor points are used to spread the solved solution to the legalized solution.
+    * ``qp-hybrid`` Solves for a placement that minimizes the quadratic HPWL of
+      the flat placement using a hybrid clique/star net model (as described in
+      FastPlace :cite:`Viswanathan2005_FastPlace`).
+      Uses the legalized solution as anchor-points to pull the solution to a
+      more legal solution (similar to the approach from SimPL :cite:`Kim2013_SimPL`).
 
-    * ``quadratic-flowbased-lookahead`` Use a Global Placer which uses a quadratic solver and a multi-commodity-flow-based lookahead legalizer. Anchor points are used to spread the solved solution to the legalized solution.
+    * ``lp-b2b`` Solves for a placement that minimizes the linear HPWL of the
+      flat placement using the Bound2Bound net model (as described in Kraftwerk2 :cite:`Spindler2008_Kraftwerk2`).
+      Uses the legalized solution as anchor-points to pull the solution to a
+      more legal solution (similar to the approach from SimPL :cite:`Kim2013_SimPL`).
 
-    **Default:** ``quadratic-bipartitioning-lookahead``
+    **Default:** ``qp-hybrid``
+
+.. option:: --ap_partial_legalizer {bipartitioning | flow-based}
+
+    Controls which Partial Legalizer the Global Placer will use in the AP Flow.
+    The Partial Legalizer legalizes a placement generated by an Analytical Solver.
+    It is used within the Global Placer to guide the solver to a more legal
+    solution.
+
+    * ``bipartitioning`` Creates minimum windows around over-dense regions of
+      the device bi-partitions the atoms in these windows such that the region
+      is no longer over-dense and the atoms are in tiles that they can be placed
+      into.
+
+    * ``flow-based`` Flows atoms from regions that are overfilled to regions that
+      are underfilled.
+
+    **Default:** ``bipartitioning``
 
 .. option:: --ap_full_legalizer {naive | appack}
 

doc/src/z_references.bib

@@ -436,3 +436,46 @@ @inproceedings{kosar2024parallel
   booktitle={The 23rd International Conference on Field-Programmable Technology},
   year={2024}
 }
+
+@ARTICLE{Viswanathan2005_FastPlace,
+    author={Viswanathan, N. and Chu, C.C.-N.},
+    journal={IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems},
+    title={{FastPlace}: efficient analytical placement using cell shifting, iterative local refinement,and a hybrid net model},
+    year={2005},
+    volume={24},
+    number={5},
+    month=may,
+    pages={722-733},
+    keywords={Clustering algorithms;Partitioning algorithms;Algorithm design and analysis;Integrated circuit interconnections;Large-scale systems;Minimization;Delay;Simulated annealing;Iterative algorithms;Acceleration;Analytical placement;computer-aided design;net models;standard cell placement},
+    doi={10.1109/TCAD.2005.846365}
+}
+
+@article{Kim2013_SimPL,
+    author = {Kim, Myung-Chul and Lee, Dong-Jin and Markov, Igor L.},
+    journal = {Commun. ACM},
+    title = {{SimPL}: an algorithm for placing {VLSI} circuits},
+    year = {2013},
+    issue_date = {June 2013},
+    publisher = {Association for Computing Machinery},
+    address = {New York, NY, USA},
+    volume = {56},
+    number = {6},
+    issn = {0001-0782},
+    doi = {10.1145/2461256.2461279},
+    month = jun,
+    pages = {105–113},
+    numpages = {9}
+}
+
+@ARTICLE{Spindler2008_Kraftwerk2,
+    author={Spindler, Peter and Schlichtmann, Ulf and Johannes, Frank M.},
+    journal={IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems},
+    title={Kraftwerk2—A Fast Force-Directed Quadratic Placement Approach Using an Accurate Net Model},
+    year={2008},
+    volume={27},
+    number={8},
+    month=aug,
+    pages={1398-1411},
+    keywords={Cost function;Central Processing Unit;Runtime;Quality control;Convergence;Computational efficiency;Integrated circuit synthesis;Stochastic processes;Circuit simulation;Bound2Bound;force-directed;half-perimeter wirelength (HPWL);Kraftwerk2;quadratic placement;Kraftwerk2;force-directed;quadratic placement;Bound2Bound;HPWL},
+    doi={10.1109/TCAD.2008.925783}
+}

vpr/src/analytical_place/analytical_placement_flow.cpp

@@ -131,7 +131,8 @@ static PartialPlacement run_global_placer(const t_ap_opts& ap_opts,
         return p_placement;
     } else {
         // Run the Global Placer
-        std::unique_ptr<GlobalPlacer> global_placer = make_global_placer(ap_opts.global_placer_type,
+        std::unique_ptr<GlobalPlacer> global_placer = make_global_placer(ap_opts.analytical_solver_type,
+                                                                         ap_opts.partial_legalizer_type,
                                                                          ap_netlist,
                                                                          prepacker,
                                                                          atom_nlist,