[AP] Generalized Argument Parsing and Added Target Density

doc/src/vpr/command_line_usage.rst

@@ -1281,6 +1281,40 @@ Analytical Placement is generally split into three stages:
 
     **Default:** ``0.5``
 
+.. option:: --ap_partial_legalizer_target_density { auto | <regex>:<float>,<float> }
+
+   Sets the target density of different physical tiles on the FPGA device
+   for the partial legalizer in the AP flow. The partial legalizer will
+   try to fill tiles up to (but not beyond) this target density. This
+   is used as a guide, the legalizer may not follow this if it must fill
+   the tile more.
+
+   The partial legalizer uses an abstraction called "mass" to describe the resources
+   used by a set of primitives in the netlist and the capacity of resources in a
+   given tile. For primitives like LUTs, FFs, and DSPs this mass can be thought of
+   as the number of pins used (but not exactly). For memories, this mass can be
+   thought of as the number of bits stored. This target density parameter lowers
+   the mass capacity of tiles.
+
+   When this option is set ot auto, VPR will select good values for the
+   target density of tiles.
+
+   reasonable values are between 0.0 and 1.0, with negative values not being allowed.
+
+   This option is similar to appack_max_dist_th, where a regex string
+   is used to set the target density of different physical tiles.
+
+   For example:
+
+     .. code-block:: none
+
+        --ap_partial_legalizer_target_density .*:0.9 "clb|memory:0.8"
+
+   Would set the target density of all physical tiles to be 0.9, except for the clb and
+   memory tiles, which will be set to a target density of 0.8.
+
+    **Default:** ``auto``
+
 .. option:: --appack_max_dist_th { auto | <regex>:<float>,<float> }
 
    Sets the maximum candidate distance thresholds for the logical block types

vpr/src/analytical_place/analytical_placement_flow.cpp

@@ -156,6 +156,7 @@ static PartialPlacement run_global_placer(const t_ap_opts& ap_opts,
                                                                          place_delay_model,
                                                                          ap_opts.ap_timing_tradeoff,
                                                                          ap_opts.generate_mass_report,
+                                                                         ap_opts.ap_partial_legalizer_target_density,
                                                                          ap_opts.num_threads,
                                                                          ap_opts.log_verbosity);
         return global_placer->place();

vpr/src/analytical_place/ap_argparse_utils.cpp

@@ -0,0 +1,156 @@
+/**
+ * @file
+ * @author  Alex Singer
+ * @date    June 2025
+ * @brief   Implementation of utility functions used for parsing AP arguments.
+ */
+#include "ap_argparse_utils.h"
+#include <regex>
+#include <string>
+#include <unordered_map>
+#include <vector>
+#include "vtr_assert.h"
+#include "vtr_log.h"
+#include "vpr_error.h"
+
+/**
+ * @brief Helper method to convert a string into a float with error checking.
+ */
+static float str_to_float_or_error(const std::string& str);
+
+/**
+ * @brief Parse the given key, value string argument. The string is expected to
+ *        be of the form:
+ *              "<key_regex>:<val1>,<val2>,<val3>"
+ *
+ * This method returns a tuple containing the regex string and a vector of the
+ * values. The vector will be of the length expected_num_vals_per_key.
+ */
+static std::tuple<std::string, std::vector<float>>
+parse_key_val_arg(const std::string& arg, unsigned expected_num_vals_per_key);
+
+std::unordered_map<std::string, std::vector<float>>
+key_to_float_argument_parser(const std::vector<std::string>& arg_vals,
+                             const std::vector<std::string>& valid_keys,
+                             unsigned expected_num_vals_per_key) {
+
+    // Create the key to float map which will be returned from this method.
+    std::unordered_map<std::string, std::vector<float>> key_to_float_map;
+
+    // Go through each of the arguments to parse.
+    for (const std::string& arg_val : arg_vals) {
+        // Parse this argument.
+        // Key is the regex string, vals is the vector of values.
+        auto [key, vals] = parse_key_val_arg(arg_val, expected_num_vals_per_key);
+
+        // Create a regex object to be used to match for valid keys.
+        std::regex key_regex(key);
+
+        // Go through each valid key and find which ones match the regex.
+        bool found_match = false;
+        for (const std::string& valid_key : valid_keys) {
+            bool is_match = std::regex_match(valid_key, key_regex);
+            if (!is_match)
+                continue;
+
+            // If this key matches the regex, set the map to the given values.
+            key_to_float_map[valid_key] = vals;
+            found_match = true;
+        }
+
+        // If no match is found for this key regex, raise a warning to the user.
+        // They may have made a mistake and may want to be warned about it.
+        if (!found_match) {
+            VTR_LOG_WARN("Unable to find a valid key that matches regex pattern: %s\n",
+                         key.c_str());
+        }
+    }
+
+    // Return the map.
+    return key_to_float_map;
+}
+
+static std::tuple<std::string, std::vector<float>>
+parse_key_val_arg(const std::string& arg, unsigned expected_num_vals_per_key) {
+    // Verify the format of the string. It must have one and only one colon.
+    unsigned colon_count = 0;
+    for (char c : arg) {
+        if (c == ':')
+            colon_count++;
+    }
+    if (colon_count != 1) {
+        VTR_LOG_ERROR("Invalid argument string: %s\n",
+                      arg.c_str());
+        VPR_FATAL_ERROR(VPR_ERROR_PACK,
+                        "Error when parsing argument string");
+    }
+
+    // Split the string along the colon.
+    auto del_pos = arg.find(':');
+    std::string key_regex_str = arg.substr(0, del_pos);
+    std::string val_list_str = arg.substr(del_pos + 1, std::string::npos);
+
+    // Verify that there are a correct number of commas given the expected number
+    // of values.
+    unsigned comma_count = 0;
+    for (char c : val_list_str) {
+        if (c == ',')
+            comma_count++;
+    }
+    if (comma_count != expected_num_vals_per_key - 1) {
+        VTR_LOG_ERROR("Invalid argument string (too many commas): %s\n",
+                      arg.c_str());
+        VPR_FATAL_ERROR(VPR_ERROR_PACK,
+                        "Error when parsing argument string");
+    }
+
+    // Collect the comma seperated values into a vector.
+    std::vector<float> vals;
+    vals.reserve(expected_num_vals_per_key);
+
+    // As we are reading each comma-seperated value, keep track of the current
+    // part of the string we are reading. We read from left to right.
+    std::string acc_val_list_str = val_list_str;
+
+    // For each expected value up to the last one, parse the current value before
+    // the comma.
+    VTR_ASSERT(expected_num_vals_per_key > 0);
+    for (unsigned i = 0; i < expected_num_vals_per_key - 1; i++) {
+        // Split the string before and after the comma.
+        auto comma_pos = acc_val_list_str.find(",");
+        VTR_ASSERT(comma_pos != std::string::npos);
+        std::string current_val_str = val_list_str.substr(0, comma_pos);
+        // Send the string after the comma to the next iteration.
+        acc_val_list_str = val_list_str.substr(comma_pos + 1, std::string::npos);
+
+        // Cast the string before the comma into a float and store it.
+        float current_val = str_to_float_or_error(current_val_str);
+        vals.push_back(current_val);
+    }
+
+    // Parse the last value in the list. This one should not have a comma in it.
+    VTR_ASSERT(acc_val_list_str.find(",") == std::string::npos);
+    float last_val = str_to_float_or_error(acc_val_list_str);
+    vals.push_back(last_val);
+
+    // Return the results as a tuple.
+    return std::make_tuple(key_regex_str, vals);
+}
+
+static float str_to_float_or_error(const std::string& str) {
+    float val = -1;
+    try {
+        val = std::stof(str);
+    } catch (const std::invalid_argument& e) {
+        VTR_LOG_ERROR("Error while parsing float arg value: %s\n"
+                      "Failed with invalid argument: %s\n",
+                      str.c_str(),
+                      e.what());
+    } catch (const std::out_of_range& e) {
+        VTR_LOG_ERROR("Error while parsing float arg value: %s\n"
+                      "Failed with out of range: %s\n",
+                      str.c_str(),
+                      e.what());
+    }
+    return val;
+}

vpr/src/analytical_place/ap_argparse_utils.h

@@ -0,0 +1,44 @@
+#pragma once
+/**
+ * @file
+ * @author  Alex Singer
+ * @date    June 2025
+ * @brief   Delcarations of utility functions used to parse AP options.
+ */
+
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+/**
+ * @brief Parser method for parsing a list of arguments of the form:
+ *      "<key_regex>:<val1>,<val2>,<val3>,..."
+ *
+ * This method will will return a map containing the value for each key matched.
+ * The map will not contain an entry for a key that was not set by the arguments.
+ *
+ * Example usage:
+ *      // Create a list of valid keys.
+ *      std::vector<std::string> valid_keys = {"foo", "bar"}
+ *
+ *      // User passed regex args. Sets all values to {0.5, 0.5, 0.5} THEN sets
+ *      // "foo" specifically to {0.1, 0.2, 0.3}.
+ *      // NOTE: Arguments are read left to right (first to last).
+ *      std::vector<std::string> arg_vals = {".*:0.5,0.5,0.5", "foo:0.1,0.2,0.3"}
+ *
+ *      auto key_to_val_map = key_to_float_argument_parser(arg_vals,
+ *                                                         valid_keys,
+ *                                                         3);
+ *      // Map will contain {0.1, 0.2, 0.3} for "foo" and {0.5, 0.5, 0.5} for "bar"
+ *
+ *  @param arg_vals
+ *      The list of arguments to parse.
+ *  @param valid_keys
+ *      A list of valid keys that the argument regex patterns can match for.
+ *  @param expected_num_vals_per_key
+ *      The expected number of floating point values per key.
+ */
+std::unordered_map<std::string, std::vector<float>>
+key_to_float_argument_parser(const std::vector<std::string>& arg_vals,
+                             const std::vector<std::string>& valid_keys,
+                             unsigned expected_num_vals_per_key = 1);

vpr/src/analytical_place/flat_placement_density_manager.cpp

@@ -7,6 +7,8 @@
 
 #include "flat_placement_density_manager.h"
 #include <tuple>
+#include <unordered_map>
+#include "ap_argparse_utils.h"
 #include "ap_netlist.h"
 #include "ap_netlist_fwd.h"
 #include "atom_netlist.h"
@@ -18,6 +20,8 @@
 #include "prepack.h"
 #include "primitive_dim_manager.h"
 #include "primitive_vector.h"
+#include "vpr_error.h"
+#include "vpr_utils.h"
 #include "vtr_assert.h"
 #include "vtr_geometry.h"
 #include "vtr_vector.h"
@@ -45,13 +49,68 @@ static PrimitiveVector calc_bin_underfill(const PrimitiveVector& bin_utilization
     return underfill;
 }
 
+/**
+ * @brief Get the physical type target densities given the user arguments.
+ *
+ * This will automatically select good target densisities, but will allow the
+ * user to override these values from the command line.
+ *
+ *  @param target_density_arg_strs
+ *      The command-line arguments provided by the user.
+ *  @param physical_tile_types
+ *      A vector of all physical tile types in the architecture.
+ */
+static std::vector<float> get_physical_type_target_densities(const std::vector<std::string>& target_density_arg_strs,
+                                                             const std::vector<t_physical_tile_type>& physical_tile_types) {
+    // Get the target densisty of each physical block type.
+    // TODO: Create auto feature to automatically select target densities based
+    //       on properties of the architecture. Need to sweep to find reasonable
+    //       values.
+    std::vector<float> phy_ty_target_density(physical_tile_types.size(), 1.0f);
+
+    // Set to auto if no user args are provided.
+    if (target_density_arg_strs.size() == 0)
+        return phy_ty_target_density;
+    if (target_density_arg_strs.size() == 1 && target_density_arg_strs[0] == "auto")
+        return phy_ty_target_density;
+
+    // Parse the user args. The physical type names are expected to be used as keys.
+    std::vector<std::string> phy_ty_names;
+    phy_ty_names.reserve(physical_tile_types.size());
+    std::unordered_map<std::string, int> phy_ty_name_to_index;
+    for (const t_physical_tile_type& phy_ty : physical_tile_types) {
+        phy_ty_names.push_back(phy_ty.name);
+        phy_ty_name_to_index[phy_ty.name] = phy_ty.index;
+    }
+    auto phy_ty_name_to_tar_density = key_to_float_argument_parser(target_density_arg_strs,
+                                                                   phy_ty_names,
+                                                                   1);
+
+    // Update the target densities based on the user args.
+    for (const auto& phy_ty_name_to_density_pair : phy_ty_name_to_tar_density) {
+        const std::string& phy_ty_name = phy_ty_name_to_density_pair.first;
+        VTR_ASSERT(phy_ty_name_to_density_pair.second.size() == 1);
+        float target_density = phy_ty_name_to_density_pair.second[0];
+        if (target_density < 0.0f) {
+            VPR_FATAL_ERROR(VPR_ERROR_AP,
+                            "Cannot have negative target density");
+        }
+
+        int phy_ty_index = phy_ty_name_to_index[phy_ty_name];
+        phy_ty_target_density[phy_ty_index] = target_density;
+    }
+
+    return phy_ty_target_density;
+}
+
 FlatPlacementDensityManager::FlatPlacementDensityManager(const APNetlist& ap_netlist,
                                                          const Prepacker& prepacker,
                                                          const AtomNetlist& atom_netlist,
                                                          const DeviceGrid& device_grid,
                                                          const std::vector<t_logical_block_type>& logical_block_types,
                                                          const std::vector<t_physical_tile_type>& physical_tile_types,
                                                          const LogicalModels& models,
+                                                         const std::vector<std::string>& target_density_arg_strs,
                                                          int log_verbosity)
     : ap_netlist_(ap_netlist)
     , bins_(ap_netlist)
@@ -62,6 +121,15 @@ FlatPlacementDensityManager::FlatPlacementDensityManager(const APNetlist& ap_net
     std::tie(num_layers, width, height) = device_grid.dim_sizes();
     bin_spatial_lookup_.resize({num_layers, width, height});
 
+    // Get the target densisty of each physical block type.
+    std::vector<float> phy_ty_target_densities = get_physical_type_target_densities(target_density_arg_strs,
+                                                                                    physical_tile_types);
+    VTR_LOG("Partial legalizer is using target densities:");
+    for (const t_physical_tile_type& phy_ty : physical_tile_types) {
+        VTR_LOG(" %s:%.1f", phy_ty.name.c_str(), phy_ty_target_densities[phy_ty.index]);
+    }
+    VTR_LOG("\n");
+
     // Create a bin for each tile. This will create one bin for each root tile
     // location.
     vtr::vector_map<FlatPlacementBinId, size_t> bin_phy_tile_type_idx;
@@ -96,6 +164,12 @@ FlatPlacementDensityManager::FlatPlacementDensityManager(const APNetlist& ap_net
                 // Store the index of the physical tile type into a map to be
                 // used to compute the capacity.
                 bin_phy_tile_type_idx.insert(new_bin_id, tile_type->index);
+
+                // Set the target density for this bin based on the physical
+                // tile type..
+                float target_density = phy_ty_target_densities[tile_type->index];
+                bin_target_density_.push_back(target_density);
+                VTR_ASSERT(bin_target_density_[new_bin_id] = target_density);
             }
         }
     }