Initial NoC Placement

vpr/src/base/read_options.cpp

@@ -2823,7 +2823,7 @@ argparse::ArgumentParser create_arg_parser(std::string prog_name, t_options& arg
         .help(
             "Sets the minimum fraction of swaps attempted by the placer that are NoC blocks."
             "This value is an integer ranging from 0-100. 0 means NoC blocks will be moved at the same rate as other blocks. 100 means all swaps attempted by the placer are NoC router blocks.")
-        .default_value("40")
+        .default_value("0")
         .show_in(argparse::ShowIn::HELP_ONLY);
 
     noc_grp.add_argument<std::string>(args.noc_placement_file_name, "--noc_placement_file_name")

vpr/src/base/vpr_context.h

@@ -344,6 +344,11 @@ struct ClusteringHelperContext : public Context {
     // the utilization of external input/output pins during packing (between 0 and 1)
     t_ext_pin_util_targets target_external_pin_util;
 
+    // During clustering, a block is related to un-clustered primitives with nets.
+    // This relation has three types: low fanout, high fanout, and trasitive
+    // high_fanout_thresholds stores the threshold for nets to a block type to be considered high fanout
+    t_pack_high_fanout_thresholds high_fanout_thresholds;
+
     // A vector of unordered_sets of AtomBlockIds that are inside each clustered block [0 .. num_clustered_blocks-1]
     // unordered_set for faster insertion/deletion during the iterative improvement process of packing
     vtr::vector<ClusterBlockId, std::unordered_set<AtomBlockId>> atoms_lookup;

vpr/src/base/vpr_types.cpp

@@ -7,15 +7,154 @@ t_ext_pin_util_targets::t_ext_pin_util_targets(float default_in_util, float defa
     defaults_.output_pin_util = default_out_util;
 }
 
-t_ext_pin_util t_ext_pin_util_targets::get_pin_util(std::string block_type_name) const {
+t_ext_pin_util_targets::t_ext_pin_util_targets(const std::vector<std::string>& specs)
+    : t_ext_pin_util_targets(1., 1.) {
+    if (specs.size() == 1 && specs[0] == "auto") {
+        //No user-specified pin utilizations, infer them automatically.
+        //
+        //We set a pin utilization target based on the block type, with
+        //the logic block having a lower utilization target and other blocks
+        //(e.g. hard blocks) having no limit.
+
+        auto& device_ctx = g_vpr_ctx.device();
+        auto& grid = device_ctx.grid;
+        t_logical_block_type_ptr logic_block_type = infer_logic_block_type(grid);
+
+        //Allowing 100% pin utilization of the logic block type can harm
+        //routability, since it may allow a few (typically outlier) clusters to
+        //use a very large number of pins -- causing routability issues. These
+        //clusters can cause failed routings where only a handful of routing
+        //resource nodes remain overused (and do not resolve) These can be
+        //avoided by putting a (soft) limit on the number of input pins which
+        //can be used, effectively clipping off the most egregeous outliers.
+        //
+        //Experiments show that limiting input utilization produces better quality
+        //than limiting output utilization (limiting input utilization implicitly
+        //also limits output utilization).
+        //
+        //For relatively high pin utilizations (e.g. > 70%) this has little-to-no
+        //impact on the number of clusters required. As a result we set a default
+        //input pin utilization target which is high, but less than 100%.
+        if (logic_block_type != nullptr) {
+            constexpr float LOGIC_BLOCK_TYPE_AUTO_INPUT_UTIL = 0.8;
+            constexpr float LOGIC_BLOCK_TYPE_AUTO_OUTPUT_UTIL = 1.0;
+
+            t_ext_pin_util logic_block_ext_pin_util(LOGIC_BLOCK_TYPE_AUTO_INPUT_UTIL, LOGIC_BLOCK_TYPE_AUTO_OUTPUT_UTIL);
+
+            set_block_pin_util(logic_block_type->name, logic_block_ext_pin_util);
+        } else {
+            VTR_LOG_WARN("Unable to identify logic block type to apply default pin utilization targets to; this may result in denser packing than desired\n");
+        }
+
+    } else {
+        //Process user specified overrides
+
+        bool default_set = false;
+        std::set<std::string> seen_block_types;
+
+        for (const auto& spec : specs) {
+            t_ext_pin_util target_ext_pin_util(1., 1.);
+
+            auto block_values = vtr::split(spec, ":");
+            std::string block_type;
+            std::string values;
+            if (block_values.size() == 2) {
+                block_type = block_values[0];
+                values = block_values[1];
+            } else if (block_values.size() == 1) {
+                values = block_values[0];
+            } else {
+                std::stringstream msg;
+                msg << "In valid block pin utilization specification '" << spec << "' (expected at most one ':' between block name and values";
+                VPR_FATAL_ERROR(VPR_ERROR_PACK, msg.str().c_str());
+            }
+
+            auto elements = vtr::split(values, ",");
+            if (elements.size() == 1) {
+                target_ext_pin_util.input_pin_util = vtr::atof(elements[0]);
+            } else if (elements.size() == 2) {
+                target_ext_pin_util.input_pin_util = vtr::atof(elements[0]);
+                target_ext_pin_util.output_pin_util = vtr::atof(elements[1]);
+            } else {
+                std::stringstream msg;
+                msg << "Invalid conversion from '" << spec << "' to external pin util (expected either a single float value, or two float values separted by a comma)";
+                VPR_FATAL_ERROR(VPR_ERROR_PACK, msg.str().c_str());
+            }
+
+            if (target_ext_pin_util.input_pin_util < 0. || target_ext_pin_util.input_pin_util > 1.) {
+                std::stringstream msg;
+                msg << "Out of range target input pin utilization '" << target_ext_pin_util.input_pin_util << "' (expected within range [0.0, 1.0])";
+                VPR_FATAL_ERROR(VPR_ERROR_PACK, msg.str().c_str());
+            }
+            if (target_ext_pin_util.output_pin_util < 0. || target_ext_pin_util.output_pin_util > 1.) {
+                std::stringstream msg;
+                msg << "Out of range target output pin utilization '" << target_ext_pin_util.output_pin_util << "' (expected within range [0.0, 1.0])";
+                VPR_FATAL_ERROR(VPR_ERROR_PACK, msg.str().c_str());
+            }
+
+            if (block_type.empty()) {
+                //Default value
+                if (default_set) {
+                    std::stringstream msg;
+                    msg << "Only one default pin utilization should be specified";
+                    VPR_FATAL_ERROR(VPR_ERROR_PACK, msg.str().c_str());
+                }
+                set_default_pin_util(target_ext_pin_util);
+                default_set = true;
+            } else {
+                if (seen_block_types.count(block_type)) {
+                    std::stringstream msg;
+                    msg << "Only one pin utilization should be specified for block type '" << block_type << "'";
+                    VPR_FATAL_ERROR(VPR_ERROR_PACK, msg.str().c_str());
+                }
+
+                set_block_pin_util(block_type, target_ext_pin_util);
+                seen_block_types.insert(block_type);
+            }
+        }
+    }
+}
+
+t_ext_pin_util_targets& t_ext_pin_util_targets::operator=(t_ext_pin_util_targets&& other) noexcept {
+    if (this != &other) {
+        defaults_ = std::move(other.defaults_);
+        overrides_ = std::move(other.overrides_);
+    }
+    return *this;
+}
+
+t_ext_pin_util t_ext_pin_util_targets::get_pin_util(const std::string& block_type_name) const {
     auto itr = overrides_.find(block_type_name);
     if (itr != overrides_.end()) {
         return itr->second;
     }
     return defaults_;
 }
 
-void t_ext_pin_util_targets::set_block_pin_util(std::string block_type_name, t_ext_pin_util target) {
+std::string t_ext_pin_util_targets::to_string() const {
+    std::stringstream ss;
+
+    auto& device_ctx = g_vpr_ctx.device();
+
+    for (unsigned int itype = 0; itype < device_ctx.physical_tile_types.size(); ++itype) {
+        if (is_empty_type(&device_ctx.physical_tile_types[itype])) continue;
+
+        auto blk_name = device_ctx.physical_tile_types[itype].name;
+
+        ss << blk_name << ":";
+
+        auto pin_util = get_pin_util(blk_name);
+        ss << pin_util.input_pin_util << ',' << pin_util.output_pin_util;
+
+        if (itype != device_ctx.physical_tile_types.size() - 1) {
+            ss << " ";
+        }
+    }
+
+    return ss.str();
+}
+
+void t_ext_pin_util_targets::set_block_pin_util(const std::string& block_type_name, t_ext_pin_util target) {
     overrides_[block_type_name] = target;
 }
 
@@ -26,22 +165,120 @@ void t_ext_pin_util_targets::set_default_pin_util(t_ext_pin_util default_target)
 t_pack_high_fanout_thresholds::t_pack_high_fanout_thresholds(int threshold)
     : default_(threshold) {}
 
+t_pack_high_fanout_thresholds::t_pack_high_fanout_thresholds(const std::vector<std::string>& specs)
+    : t_pack_high_fanout_thresholds(128) {
+    if (specs.size() == 1 && specs[0] == "auto") {
+        //No user-specified high fanout thresholds, infer them automatically.
+        //
+        //We set the high fanout threshold a based on the block type, with
+        //the logic block having a lower threshold than other blocks.
+        //(Since logic blocks are the ones which tend to be too densely
+        //clustered.)
+
+        auto& device_ctx = g_vpr_ctx.device();
+        auto& grid = device_ctx.grid;
+        t_logical_block_type_ptr logic_block_type = infer_logic_block_type(grid);
+
+        if (logic_block_type != nullptr) {
+            constexpr float LOGIC_BLOCK_TYPE_HIGH_FANOUT_THRESHOLD = 32;
+
+            set(logic_block_type->name, LOGIC_BLOCK_TYPE_HIGH_FANOUT_THRESHOLD);
+        } else {
+            VTR_LOG_WARN("Unable to identify logic block type to apply default packer high fanout thresholds; this may result in denser packing than desired\n");
+        }
+    } else {
+        //Process user specified overrides
+
+        bool default_set = false;
+        std::set<std::string> seen_block_types;
+
+        for (const auto& spec : specs) {
+            auto block_values = vtr::split(spec, ":");
+            std::string block_type;
+            std::string value;
+            if (block_values.size() == 1) {
+                value = block_values[0];
+            } else if (block_values.size() == 2) {
+                block_type = block_values[0];
+                value = block_values[1];
+            } else {
+                std::stringstream msg;
+                msg << "In valid block high fanout threshold specification '" << spec << "' (expected at most one ':' between block name and value";
+                VPR_FATAL_ERROR(VPR_ERROR_PACK, msg.str().c_str());
+            }
+
+            int threshold = vtr::atoi(value);
+
+            if (block_type.empty()) {
+                //Default value
+                if (default_set) {
+                    std::stringstream msg;
+                    msg << "Only one default high fanout threshold should be specified";
+                    VPR_FATAL_ERROR(VPR_ERROR_PACK, msg.str().c_str());
+                }
+                set_default(threshold);
+                default_set = true;
+            } else {
+                if (seen_block_types.count(block_type)) {
+                    std::stringstream msg;
+                    msg << "Only one high fanout threshold should be specified for block type '" << block_type << "'";
+                    VPR_FATAL_ERROR(VPR_ERROR_PACK, msg.str().c_str());
+                }
+
+                set(block_type, threshold);
+                seen_block_types.insert(block_type);
+            }
+        }
+    }
+}
+
+t_pack_high_fanout_thresholds& t_pack_high_fanout_thresholds::operator=(t_pack_high_fanout_thresholds&& other) noexcept {
+    if (this != &other) {
+        default_ = std::move(other.default_);
+        overrides_ = std::move(other.overrides_);
+    }
+    return *this;
+}
+
 void t_pack_high_fanout_thresholds::set_default(int threshold) {
     default_ = threshold;
 }
 
-void t_pack_high_fanout_thresholds::set(std::string block_type_name, int threshold) {
+void t_pack_high_fanout_thresholds::set(const std::string& block_type_name, int threshold) {
     overrides_[block_type_name] = threshold;
 }
 
-int t_pack_high_fanout_thresholds::get_threshold(std::string block_type_name) const {
+int t_pack_high_fanout_thresholds::get_threshold(const std::string& block_type_name) const {
     auto itr = overrides_.find(block_type_name);
     if (itr != overrides_.end()) {
         return itr->second;
     }
     return default_;
 }
 
+std::string t_pack_high_fanout_thresholds::to_string() const {
+    std::stringstream ss;
+
+    auto& device_ctx = g_vpr_ctx.device();
+
+    for (unsigned int itype = 0; itype < device_ctx.physical_tile_types.size(); ++itype) {
+        if (is_empty_type(&device_ctx.physical_tile_types[itype])) continue;
+
+        auto blk_name = device_ctx.physical_tile_types[itype].name;
+
+        ss << blk_name << ":";
+
+        auto threshold = get_threshold(blk_name);
+        ss << threshold;
+
+        if (itype != device_ctx.physical_tile_types.size() - 1) {
+            ss << " ";
+        }
+    }
+
+    return ss.str();
+}
+
 /*
  * t_pb structure function definitions
  */

vpr/src/base/vpr_types.h

@@ -194,16 +194,21 @@ class t_ext_pin_util_targets {
   public:
     t_ext_pin_util_targets() = default;
     t_ext_pin_util_targets(float default_in_util, float default_out_util);
+    t_ext_pin_util_targets(const std::vector<std::string>& specs);
+    t_ext_pin_util_targets& operator=(t_ext_pin_util_targets&& other) noexcept;
 
     ///@brief Returns the input pin util of the specified block (or default if unspecified)
-    t_ext_pin_util get_pin_util(std::string block_type_name) const;
+    t_ext_pin_util get_pin_util(const std::string& block_type_name) const;
+
+    ///@brief Returns a string describing input/output pin utilization targets
+    std::string to_string() const;
 
   public:
     /**
      * @brief Sets the pin util for the specified block type
      * @return true if non-default was previously set
      */
-    void set_block_pin_util(std::string block_type_name, t_ext_pin_util target);
+    void set_block_pin_util(const std::string& block_type_name, t_ext_pin_util target);
 
     /**
      * @brief Sets the default pin util
@@ -219,16 +224,22 @@ class t_ext_pin_util_targets {
 class t_pack_high_fanout_thresholds {
   public:
     t_pack_high_fanout_thresholds() = default;
-    t_pack_high_fanout_thresholds(int threshold);
+    explicit t_pack_high_fanout_thresholds(int threshold);
+    explicit t_pack_high_fanout_thresholds(const std::vector<std::string>& specs);
+    t_pack_high_fanout_thresholds& operator=(t_pack_high_fanout_thresholds&& other) noexcept;
+
+    ///@brief Returns the high fanout threshold of the specifi  ed block
+    int get_threshold(const std::string& block_type_name) const;
 
-    int get_threshold(std::string block_type_name) const;
+    ///@brief Returns a string describing high fanout thresholds for different block types
+    std::string to_string() const;
 
   public:
     /**
      * @brief Sets the pin util for the specified block type
      * @return true if non-default was previously set
      */
-    void set(std::string block_type_name, int threshold);
+    void set(const std::string& block_type_name, int threshold);
 
     /**
      * @brief Sets the default pin util
@@ -723,6 +734,11 @@ struct t_pl_loc {
         , y(yloc)
         , sub_tile(sub_tile_loc)
         , layer(layer_num) {}
+    t_pl_loc(const t_physical_tile_loc& phy_loc, int sub_tile_loc)
+        : x(phy_loc.x)
+        , y(phy_loc.y)
+        , sub_tile(sub_tile_loc)
+        , layer(phy_loc.layer_num) {}
 
     int x = OPEN;
     int y = OPEN;

vpr/src/noc/noc_router.cpp

@@ -27,6 +27,15 @@ int NocRouter::get_router_layer_position(void) const {
     return router_layer_position;
 }
 
+t_physical_tile_loc NocRouter::get_router_physical_location(void) const {
+    const int x = get_router_grid_position_x();
+    const int y = get_router_grid_position_y();
+    const int layer = get_router_layer_position();
+    t_physical_tile_loc phy_loc{x, y, layer};
+
+    return phy_loc;
+}
+
 ClusterBlockId NocRouter::get_router_block_ref(void) const {
     return router_block_ref;
 }

vpr/src/noc/noc_router.h

@@ -86,6 +86,12 @@ class NocRouter {
      */
     int get_router_layer_position(void) const;
 
+    /**
+     * @brief Gets the physical location where the the physical router is located
+     * @return t_physical_tile_loc that contains x-y coordinates and the layer number
+     */
+    t_physical_tile_loc get_router_physical_location(void) const;
+
     /**
      * @brief Gets the unique id of the router block that is current placed on the physical router
      * @return A ClusterBlockId that identifies a router block in the clustered netlist