enable fast bitstream building by creating a frame view of fabric

openfpga/src/base/openfpga_build_fabric.cpp

@@ -67,6 +67,7 @@ void compress_routing_hierarchy(OpenfpgaContext& openfpga_ctx,
 int build_fabric(OpenfpgaContext& openfpga_ctx,
                  const Command& cmd, const CommandContext& cmd_context) { 
 
+  CommandOptionId opt_frame_view = cmd.option("frame_view");
   CommandOptionId opt_compress_routing = cmd.option("compress_routing");
   CommandOptionId opt_duplicate_grid_pin = cmd.option("duplicate_grid_pin");
   CommandOptionId opt_gen_random_fabric_key = cmd.option("generate_random_fabric_key");
@@ -96,6 +97,7 @@ int build_fabric(OpenfpgaContext& openfpga_ctx,
                                                                   openfpga_ctx.mutable_decoder_lib(),
                                                                   const_cast<const OpenfpgaContext&>(openfpga_ctx),
                                                                   g_vpr_ctx.device(),
+                                                                  cmd_context.option_enable(cmd, opt_frame_view),
                                                                   cmd_context.option_enable(cmd, opt_compress_routing),
                                                                   cmd_context.option_enable(cmd, opt_duplicate_grid_pin),
                                                                   predefined_fabric_key,

openfpga/src/base/openfpga_setup_command.cpp

@@ -267,6 +267,9 @@ ShellCommandId add_openfpga_build_fabric_command(openfpga::Shell<OpenfpgaContext
 
   Command shell_cmd("build_fabric");
 
+  /* Add an option '--frame_view' */
+  shell_cmd.add_option("frame_view", false, "Build only frame view of the fabric (nets are skipped)");
+
   /* Add an option '--compress_routing' */
   shell_cmd.add_option("compress_routing", false, "Compress the number of unique routing modules by identifying the unique GSBs");
 

openfpga/src/fabric/build_device_module.cpp

@@ -30,6 +30,7 @@ ModuleManager build_device_module_graph(IoLocationMap& io_location_map,
                                         DecoderLibrary& decoder_lib,
                                         const OpenfpgaContext& openfpga_ctx,
                                         const DeviceContext& vpr_device_ctx,
+                                        const bool& frame_view,
                                         const bool& compress_routing,
                                         const bool& duplicate_grid_pin,
                                         const FabricKey& fabric_key,
@@ -118,7 +119,7 @@ ModuleManager build_device_module_graph(IoLocationMap& io_location_map,
                    openfpga_ctx.arch().arch_direct, 
                    openfpga_ctx.arch().config_protocol.type(),
                    sram_model,
-                   compress_routing, duplicate_grid_pin,
+                   frame_view, compress_routing, duplicate_grid_pin,
                    fabric_key, generate_random_fabric_key);
 
   /* Now a critical correction has to be done!

openfpga/src/fabric/build_device_module.h

@@ -19,6 +19,7 @@ ModuleManager build_device_module_graph(IoLocationMap& io_location_map,
                                         DecoderLibrary& decoder_lib,
                                         const OpenfpgaContext& openfpga_ctx,
                                         const DeviceContext& vpr_device_ctx,
+                                        const bool& frame_view,
                                         const bool& compress_routing,
                                         const bool& duplicate_grid_pin,
                                         const FabricKey& fabric_key,

openfpga/src/fabric/build_top_module.cpp

@@ -329,6 +329,7 @@ void build_top_module(ModuleManager& module_manager,
                       const ArchDirect& arch_direct,
                       const e_config_protocol_type& sram_orgz_type,
                       const CircuitModelId& sram_model,
+                      const bool& frame_view,
                       const bool& compact_routing_hierarchy,
                       const bool& duplicate_grid_pin,
                       const FabricKey& fabric_key,
@@ -351,6 +352,10 @@ void build_top_module(ModuleManager& module_manager,
   cb_instance_ids[CHANX] = add_top_module_connection_block_instances(module_manager, top_module, device_rr_gsb, CHANX, compact_routing_hierarchy);
   cb_instance_ids[CHANY] = add_top_module_connection_block_instances(module_manager, top_module, device_rr_gsb, CHANY, compact_routing_hierarchy);
 
+  /* Add nets when we need a complete fabric modeling,
+   * which is required by downstream functions
+   */
+  if (false == frame_view) {
     /* Reserve nets to be memory efficient */
     reserve_module_manager_module_nets(module_manager, top_module);
 
@@ -363,6 +368,7 @@ void build_top_module(ModuleManager& module_manager,
     add_top_module_nets_tile_direct_connections(module_manager, top_module, circuit_lib, 
                                                 grids, grid_instance_ids,
                                                 tile_direct, arch_direct);
+  }
 
   /* Add global ports to the pb_module:
    * This is a much easier job after adding sub modules (instances), 

openfpga/src/fabric/build_top_module.h

@@ -36,6 +36,7 @@ void build_top_module(ModuleManager& module_manager,
                       const ArchDirect& arch_direct,
                       const e_config_protocol_type& sram_orgz_type,
                       const CircuitModelId& sram_model,
+                      const bool& frame_view,
                       const bool& compact_routing_hierarchy,
                       const bool& duplicate_grid_pin,
                       const FabricKey& fabric_key,