Merge pull request #2934 from AlexandreSinger/feature-appack

[APPack] Updated How APPack Adheres to Given Placement

Author: AlexandreSinger

vpr/src/analytical_place/detailed_placer.cpp

@@ -7,13 +7,13 @@
 
 #include "detailed_placer.h"
 #include <memory>
-#include "FlatPlacementInfo.h"
 #include "PlacementDelayModelCreator.h"
 #include "ap_flow_enums.h"
 #include "atom_netlist.h"
 #include "clustered_netlist.h"
 #include "clustered_netlist_utils.h"
 #include "echo_files.h"
+#include "flat_placement_types.h"
 #include "globals.h"
 #include "physical_types.h"
 #include "place_and_route.h"
@@ -22,6 +22,7 @@
 #include "vpr_error.h"
 #include "vpr_types.h"
 #include "vpr_utils.h"
+#include "vtr_time.h"
 
 std::unique_ptr<DetailedPlacer> make_detailed_placer(e_ap_detailed_placer detailed_placer_type,
                                                      const BlkLocRegistry& curr_clustered_placement,
@@ -89,6 +90,9 @@ AnnealerDetailedPlacer::AnnealerDetailedPlacer(const BlkLocRegistry& curr_cluste
 }
 
 void AnnealerDetailedPlacer::optimize_placement() {
+    // Create a scoped timer for the detailed placer.
+    vtr::ScopedStartFinishTimer full_legalizer_timer("AP Detailed Placer");
+
     // Prevent the annealer from directly modifying the global legal placement.
     // It should only modify its own, local placement.
     g_vpr_ctx.mutable_placement().lock_loc_vars();

vpr/src/analytical_place/full_legalizer.cpp

@@ -16,23 +16,23 @@
 #include <unordered_set>
 #include <vector>
 
-#include "FlatPlacementInfo.h"
-#include "ap_flow_enums.h"
-#include "blk_loc_registry.h"
-#include "device_grid.h"
-#include "load_flat_place.h"
-#include "noc_place_utils.h"
-#include "partial_placement.h"
 #include "ShowSetup.h"
+#include "ap_flow_enums.h"
 #include "ap_netlist_fwd.h"
+#include "blk_loc_registry.h"
 #include "check_netlist.h"
 #include "cluster_legalizer.h"
 #include "cluster_util.h"
 #include "clustered_netlist.h"
+#include "device_grid.h"
+#include "flat_placement_types.h"
 #include "globals.h"
 #include "initial_placement.h"
+#include "load_flat_place.h"
 #include "logic_types.h"
+#include "noc_place_utils.h"
 #include "pack.h"
+#include "partial_placement.h"
 #include "physical_types.h"
 #include "place.h"
 #include "place_and_route.h"

vpr/src/analytical_place/global_placer.cpp

@@ -69,18 +69,24 @@ SimPLGlobalPlacer::SimPLGlobalPlacer(e_partial_legalizer partial_legalizer_type,
     // This can be a long method. Good to time this to see how long it takes to
     // construct the global placer.
     vtr::ScopedStartFinishTimer global_placer_building_timer("Constructing Global Placer");
+
     // Build the solver.
+    VTR_LOGV(log_verbosity_ >= 10, "\tBuilding the solver...\n");
     solver_ = make_analytical_solver(e_analytical_solver::QP_HYBRID,
                                      ap_netlist_);
+
     // Build the density manager used by the partial legalizer.
+    VTR_LOGV(log_verbosity_ >= 10, "\tBuilding the density manager...\n");
     density_manager_ = std::make_shared<FlatPlacementDensityManager>(ap_netlist_,
                                                                      prepacker,
                                                                      atom_netlist,
                                                                      device_grid,
                                                                      logical_block_types,
                                                                      physical_tile_types,
                                                                      log_verbosity_);
+
     // Build the partial legalizer
+    VTR_LOGV(log_verbosity_ >= 10, "\tBuilding the partial legalizer...\n");
     partial_legalizer_ = make_partial_legalizer(partial_legalizer_type,
                                                 ap_netlist_,
                                                 density_manager_,

vpr/src/base/FlatPlacementInfo.h renamed to vpr/src/base/flat_placement_types.h

@@ -1,16 +1,54 @@
 /**
  * @file
  * @author  Alex Singer
- * @date    January 2025
- * @brief   Declaration of the FlatPlacementInfo object, which is used to store
- *          flat placement information used by the packer.
+ * @date    March 2025
+ * @brief   Declaration of flat placement types used throughout VPR.
  */
 
 #pragma once
 
 #include "atom_netlist.h"
+#include "vtr_assert.h"
 #include "vtr_vector.h"
 
+/**
+ * @brief A structure representing a flat placement location on the device.
+ *
+ * This is related to the t_pl_loc type; however this uses floating point
+ * coordinates, allowing for blocks to be placed in illegal positions.
+ */
+struct t_flat_pl_loc {
+    float x;     /**< The x-coordinate of the location. */
+    float y;     /**< The y-coordinate of the location. */
+    float layer; /**< The layer of the location. */
+
+    /**
+     * @brief Adds the coordinates of another t_flat_pl_loc to this one.
+     *
+     * @param other The other t_flat_pl_loc whose coordinates are to be added.
+     * @return A reference to this t_flat_pl_loc after addition.
+     */
+    t_flat_pl_loc& operator+=(const t_flat_pl_loc& other) {
+        x += other.x;
+        y += other.y;
+        layer += other.layer;
+        return *this;
+    }
+
+    /**
+     * @brief Divides the coordinates of this t_flat_pl_loc by a divisor.
+     *
+     * @param divisor The value by which to divide the coordinates.
+     * @return A reference to this t_flat_pl_loc after division.
+     */
+    t_flat_pl_loc& operator/=(float divisor) {
+        x /= divisor;
+        y /= divisor;
+        layer /= divisor;
+        return *this;
+    }
+};
+
 /**
  * @brief Flat placement storage class.
  *
@@ -55,6 +93,15 @@ class FlatPlacementInfo {
     ///        object, false otherwise.
     bool valid;
 
+    /**
+     * @brief Get the flat placement location of the given atom block.
+     */
+    inline t_flat_pl_loc get_pos(AtomBlockId blk_id) const {
+        VTR_ASSERT_SAFE_MSG(blk_id.is_valid(), "Block ID is invalid");
+        VTR_ASSERT_SAFE_MSG(valid, "FlatPlacementInfo not initialized");
+        return {blk_x_pos[blk_id], blk_y_pos[blk_id], blk_layer[blk_id]};
+    }
+
     /**
      * @brief Default constructor of this class.
      *

vpr/src/base/flat_placement_utils.h

@@ -0,0 +1,20 @@
+/**
+ * @file
+ * @author  Alex Singer
+ * @date    March 2025
+ * @brief   Utility methods for working with flat placements.
+ */
+
+#pragma once
+
+#include <cstdlib>
+#include "flat_placement_types.h"
+
+/**
+ * @brief Returns the manhattan distance (L1 distance) between two flat
+ *        placement locations.
+ */
+inline float get_manhattan_distance(const t_flat_pl_loc& loc_a,
+                                    const t_flat_pl_loc& loc_b) {
+    return std::abs(loc_a.x - loc_b.x) + std::abs(loc_a.y - loc_b.y) + std::abs(loc_a.layer - loc_b.layer);
+}

vpr/src/base/load_flat_place.cpp

@@ -14,7 +14,7 @@
 #include "atom_lookup.h"
 #include "atom_netlist.h"
 #include "clustered_netlist.h"
-#include "FlatPlacementInfo.h"
+#include "flat_placement_types.h"
 #include "globals.h"
 #include "vpr_context.h"
 #include "vpr_error.h"

vpr/src/base/place_and_route.cpp

@@ -4,7 +4,7 @@
 #include <cmath>
 #include <algorithm>
 
-#include "FlatPlacementInfo.h"
+#include "flat_placement_types.h"
 #include "place_macro.h"
 #include "vtr_assert.h"
 #include "vtr_log.h"

vpr/src/base/vpr_api.cpp

@@ -17,7 +17,7 @@
 #include <memory>
 #include <vector>
 
-#include "FlatPlacementInfo.h"
+#include "flat_placement_types.h"
 #include "cluster_util.h"
 #include "physical_types.h"
 #include "place_macro.h"

vpr/src/base/vpr_context.h

@@ -5,7 +5,7 @@
 #include <vector>
 #include <mutex>
 
-#include "FlatPlacementInfo.h"
+#include "flat_placement_types.h"
 #include "physical_types.h"
 #include "place_macro.h"
 #include "user_place_constraints.h"

vpr/src/pack/appack_context.h

@@ -0,0 +1,110 @@
+/**
+ * @file
+ * @author  Alex Siner
+ * @date    March 2025
+ * @brief   Declaration of the APPack Context object which stores all the
+ *          information used to configure APPack in the packer.
+ */
+
+#pragma once
+
+#include <algorithm>
+#include <limits>
+#include "device_grid.h"
+#include "flat_placement_types.h"
+#include "vpr_context.h"
+
+/**
+ * @brief Configuration options for APPack.
+ *
+ * APPack is an upgrade to the AAPack algorithm which uses an atom-level placement
+ * to inform the packer into creating better clusters. These options configure
+ * how APPack interprets the flat placement information.
+ */
+struct t_appack_options {
+    // Constructor for the appack options.
+    t_appack_options(const FlatPlacementInfo& flat_placement_info,
+                     const DeviceGrid& device_grid) {
+        // If the flat placement info is valid, we want to use APPack.
+        // TODO: Should probably check that all the information is valid here.
+        use_appack = flat_placement_info.valid;
+
+        // Set the max candidate distance as being some fraction of the longest
+        // distance on the device (from the bottom corner to the top corner).
+        // We also use an offset for the minimum this distance can be to prevent
+        // small devices from finding candidates.
+        float max_candidate_distance_scale = 0.5f;
+        float max_candidate_distance_offset = 20.f;
+        // Longest L1 distance on the device.
+        float longest_distance = device_grid.width() + device_grid.height();
+        max_candidate_distance = std::max(max_candidate_distance_scale * longest_distance,
+                                          max_candidate_distance_offset);
+    }
+
+    // Whether to use APPack or not.
+    // This is initialized in the constructor based on if the flat placement
+    // info is valid or not.
+    bool use_appack = false;
+
+    // =========== Cluster location ======================================== //
+    // What is the location of the cluster being created relative to the
+    // molecules being packed into it.
+    enum class e_cl_loc_ty {
+        CENTROID, /**< The location of the cluster is the centroid of the molecules which have been packed into it. */
+        SEED      /**< The location of the cluster is the location of the first molecule packed into it. */
+    };
+    e_cl_loc_ty cluster_location_ty = e_cl_loc_ty::CENTROID;
+
+    // =========== Candidate gain attenuation ============================== //
+    // These terms are used to update the gain of a given candidate based on
+    // its distance (d) relative to the location of the cluster being constructed.
+    //      gain_new = attenuation * gain_original
+    // We use the following gain attenuation function:
+    //      attenuation = { 1 - (quad_fac * d)^2    if d < dist_th
+    //                    { 1 / sqrt(d - sqrt_offset)  if d >= dist_th
+    // Distance threshold which decides when to use quadratic decay or inverted
+    // sqrt decay. If the distance is less than this threshold, quadratic decay
+    // is used. Inverted sqrt is used otherwise.
+    float dist_th = 1.0f;
+    // Horizontal offset to the inverted sqrt decay.
+    float sqrt_offset = -2.9f;
+    // Scaling factor for the quadratic decay term.
+    float quad_fac = 0.7f;
+
+    // =========== Candidate selection distance ============================ //
+    // When selecting candidates, what distance from the cluster will we
+    // consider? Any candidate beyond this distance will not be proposed.
+    // This is set in the constructor.
+    // TODO: It may be a good idea to have max different distances for different
+    //       types of molecules / clusters. For example, CLBs vs DSPs
+    float max_candidate_distance = std::numeric_limits<float>::max();
+
+    // TODO: Investigate adding flat placement info to unrelated clustering.
+
+    // TODO: Investigate adding flat placement info to seed selection.
+};
+
+/**
+ * @brief State relating to APPack.
+ *
+ * This class is intended to contain information on using flat placement
+ * information in packing.
+ */
+struct APPackContext : public Context {
+    /**
+     * @brief Constructor for the APPack context.
+     */
+    APPackContext(const FlatPlacementInfo& fplace_info, const DeviceGrid& device_grid)
+        : appack_options(fplace_info, device_grid)
+        , flat_placement_info(fplace_info) {}
+
+    /**
+     * @brief Options used to configure APPack.
+     */
+    t_appack_options appack_options;
+
+    /**
+     * @brief The flat placement information passed into APPack.
+     */
+    const FlatPlacementInfo& flat_placement_info;
+};

vpr/src/pack/cluster_legalizer.h

@@ -445,6 +445,13 @@ class ClusterLegalizer {
         return cluster.pr;
     }
 
+    /// @brief Gets the molecules currently packed within the given cluster.
+    inline const std::vector<PackMoleculeId>& get_cluster_molecules(LegalizationClusterId cluster_id) const {
+        VTR_ASSERT_SAFE(cluster_id.is_valid() && (size_t)cluster_id < legalization_clusters_.size());
+        const LegalizationCluster& cluster = legalization_clusters_[cluster_id];
+        return cluster.molecules;
+    }
+
     /// @brief Gets the current number of molecules in the cluster.
     inline size_t get_num_molecules_in_cluster(LegalizationClusterId cluster_id) const {
         VTR_ASSERT_SAFE(cluster_id.is_valid() && (size_t)cluster_id < legalization_clusters_.size());