lookahead: add new extended map lookahead

This lookahead generates a map with a more complex and complete way of
sampling and expanding the nodes to reach all destinations.

The dijkstra expansion is parallelized to overcome the higher number of
samples needed.

It also adds a penalty cost factor based on distance between the origin
and destination nodes.

Signed-off-by: Alessandro Comodi <[email protected]>

Author: acomodi

libs/libvtrcapnproto/CMakeLists.txt

@@ -22,6 +22,7 @@ set(CAPNP_DEFS
     matrix.capnp
     gen/rr_graph_uxsdcxx.capnp
     map_lookahead.capnp
+    extended_map_lookahead.capnp
     )
 capnp_generate_cpp(CAPNP_SRCS CAPNP_HDRS
     ${CAPNP_DEFS}

libs/libvtrcapnproto/extended_map_lookahead.capnp

@@ -0,0 +1,25 @@
+@0x876ec83c2fea5a18;
+
+using Matrix = import "matrix.capnp";
+
+struct VprCostEntry {
+    delay @0 :Float32;
+    congestion @1 :Float32;
+    fill @2 :Bool;
+}
+
+struct VprVector2D {
+    x @0 :Int64;
+    y @1 :Int64;
+}
+
+struct VprFloatEntry {
+    value @0 :Float32;
+}
+
+struct VprCostMap {
+    costMap @0 :Matrix.Matrix((Matrix.Matrix(VprCostEntry)));
+    offset @1 :Matrix.Matrix(VprVector2D);
+    depField @2 :List(Int64);
+    penalty @3 :Matrix.Matrix(VprFloatEntry);
+}

vpr/src/base/ShowSetup.cpp

@@ -298,6 +298,9 @@ static void ShowRouterOpts(const t_router_opts& RouterOpts) {
                 case e_router_lookahead::MAP:
                     VTR_LOG("MAP\n");
                     break;
+                case e_router_lookahead::EXTENDED_MAP:
+                    VTR_LOG("EXTENDED_MAP\n");
+                    break;
                 case e_router_lookahead::NO_OP:
                     VTR_LOG("NO_OP\n");
                     break;

vpr/src/base/read_options.cpp

@@ -692,6 +692,8 @@ struct ParseRouterLookahead {
             conv_value.set_value(e_router_lookahead::CLASSIC);
         else if (str == "map")
             conv_value.set_value(e_router_lookahead::MAP);
+        else if (str == "extended_map")
+            conv_value.set_value(e_router_lookahead::EXTENDED_MAP);
         else {
             std::stringstream msg;
             msg << "Invalid conversion from '"
@@ -707,15 +709,17 @@ struct ParseRouterLookahead {
         ConvertedValue<std::string> conv_value;
         if (val == e_router_lookahead::CLASSIC)
             conv_value.set_value("classic");
-        else {
-            VTR_ASSERT(val == e_router_lookahead::MAP);
+        else if (val == e_router_lookahead::MAP) {
             conv_value.set_value("map");
+        } else {
+            VTR_ASSERT(val == e_router_lookahead::EXTENDED_MAP);
+            conv_value.set_value("extended_map");
         }
         return conv_value;
     }
 
     std::vector<std::string> default_choices() {
-        return {"classic", "map"};
+        return {"classic", "map", "extended_map"};
     }
 };
 
@@ -1911,7 +1915,9 @@ argparse::ArgumentParser create_arg_parser(std::string prog_name, t_options& arg
             "Controls what lookahead the router uses to calculate cost of completing a connection.\n"
             " * classic: The classic VPR lookahead (may perform better on un-buffered routing\n"
             "            architectures)\n"
-            " * map: A more advanced lookahead which accounts for diverse wire type\n")
+            " * map: An advanced lookahead which accounts for diverse wire type\n"
+            " * extended_map: A more advanced and extended lookahead which accounts for a more\n"
+            "                 exhaustive node sampling method")
         .default_value("map")
         .show_in(argparse::ShowIn::HELP_ONLY);
 

vpr/src/base/vpr_types.h

@@ -110,9 +110,10 @@ constexpr const char* EMPTY_BLOCK_NAME = "EMPTY";
 #endif
 
 enum class e_router_lookahead {
-    CLASSIC, ///<VPR's classic lookahead (assumes uniform wire types)
-    MAP,     ///<Lookahead considering different wire types (see Oleg Petelin's MASc Thesis)
-    NO_OP    ///<A no-operation lookahead which always returns zero
+    CLASSIC,      ///<VPR's classic lookahead (assumes uniform wire types)
+    MAP,          ///<Lookahead considering different wire types (see Oleg Petelin's MASc Thesis)
+    EXTENDED_MAP, ///<Lookahead with a more extensive node sampling method
+    NO_OP         ///<A no-operation lookahead which always returns zero
 };
 
 enum class e_route_bb_update {

vpr/src/route/route_timing.cpp

@@ -37,6 +37,7 @@
 #include "connection_router.h"
 
 #include "router_lookahead_map.h"
+#include "router_lookahead_extended_map.h"
 
 #include "tatum/TimingReporter.hpp"
 

vpr/src/route/router_lookahead.cpp

@@ -1,6 +1,7 @@
 #include "router_lookahead.h"
 
 #include "router_lookahead_map.h"
+#include "router_lookahead_extended_map.h"
 #include "vpr_error.h"
 #include "globals.h"
 #include "route_timing.h"
@@ -13,6 +14,8 @@ static std::unique_ptr<RouterLookahead> make_router_lookahead_object(e_router_lo
         return std::make_unique<ClassicLookahead>();
     } else if (router_lookahead_type == e_router_lookahead::MAP) {
         return std::make_unique<MapLookahead>();
+    } else if (router_lookahead_type == e_router_lookahead::EXTENDED_MAP) {
+        return std::make_unique<ExtendedMapLookahead>();
     } else if (router_lookahead_type == e_router_lookahead::NO_OP) {
         return std::make_unique<NoOpLookahead>();
     }