diff --git a/openfpga/src/annotation/device_rr_gsb.cpp b/openfpga/src/annotation/device_rr_gsb.cpp
index 78ce8e16b..ccbda2bbc 100644
--- a/openfpga/src/annotation/device_rr_gsb.cpp
+++ b/openfpga/src/annotation/device_rr_gsb.cpp
@@ -1,8 +1,12 @@
 /************************************************************************
  * Member functions for class DeviceRRGSB
  ***********************************************************************/
+
 #include "device_rr_gsb.h"
 
+#include <fstream>
+#include <iostream>
+
 #include "rr_gsb_utils.h"
 #include "vtr_assert.h"
 #include "vtr_log.h"
@@ -171,6 +175,18 @@ void DeviceRRGSB::reserve(const vtr::Point<size_t>& coordinate) {
     cby_unique_module_id_[x].resize(coordinate.y());
   }
 }
+void DeviceRRGSB::reserve_unique_modules(const vtr::Point<size_t>& coordinate) {
+  sb_unique_module_id_.resize(coordinate.x());
+  cbx_unique_module_id_.resize(coordinate.x());
+  cby_unique_module_id_.resize(coordinate.x());
+
+  for (size_t x = 0; x < coordinate.x(); ++x) {
+    sb_unique_module_id_[x].resize(coordinate.y());
+
+    cbx_unique_module_id_[x].resize(coordinate.y());
+    cby_unique_module_id_[x].resize(coordinate.y());
+  }
+}
 
 /* Resize rr_switch_block array is needed*/
 void DeviceRRGSB::resize_upon_need(const vtr::Point<size_t>& coordinate) {
@@ -410,6 +426,18 @@ void DeviceRRGSB::clear() {
   clear_sb_unique_module_id();
 }
 
+void DeviceRRGSB::clear_unique_modules() {
+  /* clean unique module lists */
+  clear_cb_unique_module(CHANX);
+  clear_cb_unique_module_id(CHANX);
+
+  clear_cb_unique_module(CHANY);
+  clear_cb_unique_module_id(CHANY);
+
+  clear_sb_unique_module();
+  clear_sb_unique_module_id();
+}
+
 void DeviceRRGSB::clear_gsb() {
   /* clean gsb array */
   for (size_t x = 0; x < rr_gsb_.size(); ++x) {
@@ -551,4 +579,144 @@ size_t DeviceRRGSB::get_cb_unique_module_index(
   return cb_unique_module_id;
 }
 
+void DeviceRRGSB::preload_unique_cbx_module(
+  const vtr::Point<size_t> block_coordinate,
+  const std::vector<vtr::Point<size_t>> instance_coords) {
+  /* Add to list if this is a unique mirror*/
+  size_t limit_x = cbx_unique_module_id_.size();
+  size_t limit_y = cbx_unique_module_id_[0].size();
+
+  VTR_ASSERT(block_coordinate.x() < limit_x);
+  VTR_ASSERT(block_coordinate.y() < limit_y);
+  add_cb_unique_module(CHANX, block_coordinate);
+  /* Record the id of unique mirror */
+  set_cb_unique_module_id(CHANX, block_coordinate,
+                          get_num_cb_unique_module(CHANX) - 1);
+
+  /* Traverse the unique_mirror list and set up its module id */
+  for (auto instance_location : instance_coords) {
+    /* Record the id of unique mirror */
+    VTR_ASSERT(instance_location.x() < limit_x);
+    VTR_ASSERT(instance_location.y() < limit_y);
+    set_cb_unique_module_id(
+      CHANX, instance_location,
+      cbx_unique_module_id_[block_coordinate.x()][block_coordinate.y()]);
+  }
+}
+
+void DeviceRRGSB::preload_unique_cby_module(
+  const vtr::Point<size_t> block_coordinate,
+  const std::vector<vtr::Point<size_t>> instance_coords) {
+  /* Add to list if this is a unique mirror*/
+  size_t limit_x = cby_unique_module_id_.size();
+  size_t limit_y = cby_unique_module_id_[0].size();
+
+  VTR_ASSERT(block_coordinate.x() < limit_x);
+  VTR_ASSERT(block_coordinate.y() < limit_y);
+  add_cb_unique_module(CHANY, block_coordinate);
+  /* Record the id of unique mirror */
+  set_cb_unique_module_id(CHANY, block_coordinate,
+                          get_num_cb_unique_module(CHANY) - 1);
+
+  /* Traverse the unique_mirror list and set up its module id */
+  for (auto instance_location : instance_coords) {
+    /* Record the id of unique mirror */
+    VTR_ASSERT(instance_location.x() < limit_x);
+    VTR_ASSERT(instance_location.y() < limit_y);
+    set_cb_unique_module_id(
+      CHANY, instance_location,
+      cby_unique_module_id_[block_coordinate.x()][block_coordinate.y()]);
+  }
+}
+
+void DeviceRRGSB::preload_unique_sb_module(
+  const vtr::Point<size_t> block_coordinate,
+  const std::vector<vtr::Point<size_t>> instance_coords) {
+  /*input block coordinate should be within gsb coord range*/
+  VTR_ASSERT(block_coordinate.x() < sb_unique_module_id_.size());
+  VTR_ASSERT(block_coordinate.y() < sb_unique_module_id_[0].size());
+  sb_unique_module_.push_back(block_coordinate);
+  /* Record the id of unique module */
+  sb_unique_module_id_[block_coordinate.x()][block_coordinate.y()] =
+    sb_unique_module_.size() - 1;
+
+  /* each mirror instance of the unique module will have the same module id as
+   * the unique module */
+  for (auto instance_location : instance_coords) {
+    VTR_ASSERT(instance_location.x() < sb_unique_module_id_.size());
+    VTR_ASSERT(instance_location.y() < sb_unique_module_id_[0].size());
+    sb_unique_module_id_[instance_location.x()][instance_location.y()] =
+      sb_unique_module_id_[block_coordinate.x()][block_coordinate.y()];
+  }
+}
+
+void DeviceRRGSB::get_id_unique_sb_block_map(
+  std::map<int, vtr::Point<size_t>>& id_unique_block_map) const {
+  for (size_t id = 0; id < get_num_sb_unique_module(); ++id) {
+    const auto& unique_block_coord = sb_unique_module_[id];
+    auto unique_module_id =
+      sb_unique_module_id_[unique_block_coord.x()][unique_block_coord.y()];
+    id_unique_block_map[unique_module_id] = unique_block_coord;
+  }
+}
+
+void DeviceRRGSB::get_id_sb_instance_map(
+  std::map<int, std::vector<vtr::Point<size_t>>>& id_instance_map) const {
+  for (size_t location_x = 0; location_x < sb_unique_module_id_.size();
+       ++location_x) {
+    for (size_t location_y = 0; location_y < sb_unique_module_id_[0].size();
+         ++location_y) {
+      auto unique_module_id = sb_unique_module_id_[location_x][location_y];
+      vtr::Point<size_t> instance_coord(location_x, location_y);
+      id_instance_map[unique_module_id].push_back(instance_coord);
+    }
+  }
+}
+
+void DeviceRRGSB::get_id_unique_cbx_block_map(
+  std::map<int, vtr::Point<size_t>>& id_unique_block_map) const {
+  for (size_t id = 0; id < get_num_cb_unique_module(CHANX); ++id) {
+    const auto& unique_block_coord = cbx_unique_module_[id];
+    auto unique_module_id =
+      cbx_unique_module_id_[unique_block_coord.x()][unique_block_coord.y()];
+    id_unique_block_map[unique_module_id] = unique_block_coord;
+  }
+}
+
+void DeviceRRGSB::get_id_cbx_instance_map(
+  std::map<int, std::vector<vtr::Point<size_t>>>& id_instance_map) const {
+  for (size_t location_x = 0; location_x < cbx_unique_module_id_.size();
+       ++location_x) {
+    for (size_t location_y = 0; location_y < cbx_unique_module_id_[0].size();
+         ++location_y) {
+      auto unique_module_id = cbx_unique_module_id_[location_x][location_y];
+      vtr::Point<size_t> instance_coord(location_x, location_y);
+      id_instance_map[unique_module_id].push_back(instance_coord);
+    }
+  }
+}
+
+void DeviceRRGSB::get_id_unique_cby_block_map(
+  std::map<int, vtr::Point<size_t>>& id_unique_block_map) const {
+  for (size_t id = 0; id < get_num_cb_unique_module(CHANY); ++id) {
+    const auto& unique_block_coord = cby_unique_module_[id];
+    auto unique_module_id =
+      cby_unique_module_id_[unique_block_coord.x()][unique_block_coord.y()];
+    id_unique_block_map[unique_module_id] = unique_block_coord;
+  }
+}
+
+void DeviceRRGSB::get_id_cby_instance_map(
+  std::map<int, std::vector<vtr::Point<size_t>>>& id_instance_map) const {
+  for (size_t location_x = 0; location_x < cby_unique_module_id_.size();
+       ++location_x) {
+    for (size_t location_y = 0; location_y < cby_unique_module_id_[0].size();
+         ++location_y) {
+      auto unique_module_id = cby_unique_module_id_[location_x][location_y];
+      vtr::Point<size_t> instance_coord(location_x, location_y);
+      id_instance_map[unique_module_id].push_back(instance_coord);
+    }
+  }
+}
+
 } /* End namespace openfpga*/
diff --git a/openfpga/src/annotation/device_rr_gsb.h b/openfpga/src/annotation/device_rr_gsb.h
index b278985c6..f9a151f05 100644
--- a/openfpga/src/annotation/device_rr_gsb.h
+++ b/openfpga/src/annotation/device_rr_gsb.h
@@ -68,11 +68,14 @@ class DeviceRRGSB {
   size_t get_cb_unique_module_index(const t_rr_type& cb_type,
                                     const vtr::Point<size_t>& coordinate) const;
 
- public: /* Mutators */
+ public:                          /* Mutators */
+  void build_gsb_unique_module(); /* Add a switch block to the array, which will
+                                     automatically identify and update the lists
+                                     of unique mirrors and rotatable mirrors */
   void reserve(
     const vtr::Point<size_t>& coordinate); /* Pre-allocate the rr_switch_block
                                               array that the device requires */
-  void reserve_sb_unique_submodule_id(
+  void reserve_unique_modules(
     const vtr::Point<size_t>&
       coordinate); /* Pre-allocate the rr_sb_unique_module_id matrix that the
                       device requires */
@@ -95,8 +98,31 @@ class DeviceRRGSB {
                                      automatically identify and update the lists
                                      of unique mirrors and rotatable mirrors */
   void clear();                   /* clean the content */
- private:                         /* Internal cleaners */
-  void clear_gsb();               /* clean the content */
+  void preload_unique_cbx_module(
+    const vtr::Point<size_t> block_coordinate,
+    const std::vector<vtr::Point<size_t>> instance_coords);
+  void preload_unique_cby_module(
+    const vtr::Point<size_t> block_coordinate,
+    const std::vector<vtr::Point<size_t>> instance_coords);
+  void preload_unique_sb_module(
+    const vtr::Point<size_t> block_coordinate,
+    const std::vector<vtr::Point<size_t>> instance_coords);
+  void clear_unique_modules();
+  void get_id_sb_instance_map(
+    std::map<int, std::vector<vtr::Point<size_t>>>& id_instance_map) const;
+  void get_id_unique_sb_block_map(
+    std::map<int, vtr::Point<size_t>>& id_unique_block_map) const;
+  void get_id_cbx_instance_map(
+    std::map<int, std::vector<vtr::Point<size_t>>>& id_instance_map) const;
+  void get_id_unique_cbx_block_map(
+    std::map<int, vtr::Point<size_t>>& id_unique_block_map) const;
+  void get_id_cby_instance_map(
+    std::map<int, std::vector<vtr::Point<size_t>>>& id_instance_map) const;
+  void get_id_unique_cby_block_map(
+    std::map<int, vtr::Point<size_t>>& id_unique_block_map) const;
+
+ private:                                                /* Internal cleaners */
+  void clear_gsb();                                      /* clean the content */
   void clear_cb_unique_module(const t_rr_type& cb_type); /* clean the content */
   void clear_cb_unique_module_id(
     const t_rr_type& cb_type);       /* clean the content */
@@ -133,10 +159,8 @@ class DeviceRRGSB {
     const t_rr_type&
       cb_type); /* Add a switch block to the array, which will automatically
                    identify and update the lists of unique side module */
-  void build_gsb_unique_module(); /* Add a switch block to the array, which will
-                                     automatically identify and update the lists
-                                     of unique mirrors and rotatable mirrors */
- private:                         /* Internal Data */
+
+ private: /* Internal Data */
   std::vector<std::vector<RRGSB>> rr_gsb_;
 
   std::vector<std::vector<size_t>>
diff --git a/openfpga/src/base/openfpga_build_fabric_template.h b/openfpga/src/base/openfpga_build_fabric_template.h
index b36903a22..357b70288 100644
--- a/openfpga/src/base/openfpga_build_fabric_template.h
+++ b/openfpga/src/base/openfpga_build_fabric_template.h
@@ -20,6 +20,7 @@
 #include "read_xml_io_name_map.h"
 #include "read_xml_module_name_map.h"
 #include "read_xml_tile_config.h"
+#include "read_write_xml_unique_blocks.h"
 #include "rename_modules.h"
 #include "vtr_log.h"
 #include "vtr_time.h"
@@ -100,6 +101,7 @@ int build_fabric_template(T& 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_preload = cmd.option("preload_unique_blocks");
   CommandOptionId opt_duplicate_grid_pin = cmd.option("duplicate_grid_pin");
   CommandOptionId opt_gen_random_fabric_key =
     cmd.option("generate_random_fabric_key");
@@ -142,11 +144,15 @@ int build_fabric_template(T& openfpga_ctx, const Command& cmd,
     }
   }
 
-  if (true == cmd_context.option_enable(cmd, opt_compress_routing)) {
+  if (true == cmd_context.option_enable(cmd, opt_compress_routing) &&
+      false == cmd_context.option_enable(cmd, opt_preload)) {
     compress_routing_hierarchy_template<T>(
       openfpga_ctx, cmd_context.option_enable(cmd, opt_verbose));
     /* Update flow manager to enable compress routing */
     openfpga_ctx.mutable_flow_manager().set_compress_routing(true);
+  } else if (true == cmd_context.option_enable(cmd, opt_compress_routing) &&
+      true == cmd_context.option_enable(cmd, opt_preload)){
+    openfpga_ctx.mutable_flow_manager().set_compress_routing(true);
   }
 
   VTR_LOG("\n");
@@ -472,6 +478,54 @@ int write_fabric_pin_physical_location_template(
     cmd_context.option_enable(cmd, opt_verbose));
 }
 
+template <class T>
+int read_unique_blocks_template(T& openfpga_ctx, const Command& cmd,
+                                const CommandContext& cmd_context) {
+  CommandOptionId opt_verbose = cmd.option("verbose");
+  CommandOptionId opt_file = cmd.option("file");
+  CommandOptionId opt_type = cmd.option("type");
+
+  /* Check the option '--file' is enabled or not
+   * Actually, it must be enabled as the shell interface will check
+   * before reaching this fuction
+   */
+  VTR_ASSERT(true == cmd_context.option_enable(cmd, opt_file));
+  VTR_ASSERT(false == cmd_context.option_value(cmd, opt_file).empty());
+
+  std::string file_name = cmd_context.option_value(cmd, opt_file);
+  std::string file_type = cmd_context.option_value(cmd, opt_type);
+  /* Write hierarchy to a file */
+  if (file_type == "xml") {
+    return read_xml_unique_blocks(openfpga_ctx, file_name.c_str(),
+                                  file_type.c_str(),
+                                  cmd_context.option_enable(cmd, opt_verbose));
+  } else {
+    VTR_LOG_ERROR("file type %s not supported", file_type);
+  }
+}
+
+template <class T>
+int write_unique_blocks_template(T& openfpga_ctx, const Command& cmd,
+                                 const CommandContext& cmd_context) {
+  CommandOptionId opt_verbose = cmd.option("verbose");
+  CommandOptionId opt_file = cmd.option("file");
+  CommandOptionId opt_type = cmd.option("type");
+
+  /* Check the option '--file' is enabled or not
+   * Actually, it must be enabled as the shell interface will check
+   * before reaching this fuction
+   */
+  VTR_ASSERT(true == cmd_context.option_enable(cmd, opt_file));
+  VTR_ASSERT(false == cmd_context.option_value(cmd, opt_file).empty());
+
+  std::string file_name = cmd_context.option_value(cmd, opt_file);
+  std::string file_type = cmd_context.option_value(cmd, opt_type);
+
+  /* Write hierarchy to a file */
+  return write_xml_unique_blocks(openfpga_ctx, file_name.c_str(),
+                                 file_type.c_str(),
+                                 cmd_context.option_enable(cmd, opt_verbose));
+}
 } /* end namespace openfpga */
 
 #endif
diff --git a/openfpga/src/base/openfpga_setup_command_template.h b/openfpga/src/base/openfpga_setup_command_template.h
index 53e43f00f..fe5662000 100644
--- a/openfpga/src/base/openfpga_setup_command_template.h
+++ b/openfpga/src/base/openfpga_setup_command_template.h
@@ -391,6 +391,10 @@ ShellCommandId add_build_fabric_command_template(
                        "Compress the number of unique routing modules by "
                        "identifying the unique GSBs");
 
+  /* Add an option '--preload_unique_blocks' */
+  shell_cmd.add_option("preload_unique_blocks", false,
+                       "preload unique routing modules from user input xml file");
+
   /* Add an option '--duplicate_grid_pin' */
   shell_cmd.add_option("duplicate_grid_pin", false,
                        "Duplicate the pins on the same side of a grid");
@@ -930,6 +934,80 @@ ShellCommandId add_write_fabric_pin_physical_location_command_template(
   return shell_cmd_id;
 }
 
+/********************************************************************
+ * - Add a command to Shell environment: read_unique_blocks
+ * - Add associated options
+ * - Add command dependency
+ *******************************************************************/
+template <class T>
+ShellCommandId add_read_unique_blocks_command_template(
+  openfpga::Shell<T>& shell, const ShellCommandClassId& cmd_class_id,
+  const std::vector<ShellCommandId>& dependent_cmds, const bool& hidden) {
+  Command shell_cmd("read_unique_blocks");
+
+  /* Add an option '--file' */
+  CommandOptionId opt_file =
+    shell_cmd.add_option("file", true, "specify the unique blocks xml file");
+  shell_cmd.set_option_require_value(opt_file, openfpga::OPT_STRING);
+
+  /* Add an option '--type' */
+  CommandOptionId opt_type = shell_cmd.add_option(
+    "type", true, "specify the type of the unique blocks xml file");
+  shell_cmd.set_option_require_value(opt_type, openfpga::OPT_STRING);
+
+  /* Add an option '--verbose' */
+  shell_cmd.add_option("verbose", false, "Show verbose outputs");
+
+  /* Add command 'compact_routing_hierarchy' to the Shell */
+  ShellCommandId shell_cmd_id =
+    shell.add_command(shell_cmd, "Preload unique blocks from xml file", hidden);
+  shell.set_command_class(shell_cmd_id, cmd_class_id);
+  shell.set_command_execute_function(shell_cmd_id,
+                                     read_unique_blocks_template<T>);
+
+  /* Add command dependency to the Shell */
+  shell.set_command_dependency(shell_cmd_id, dependent_cmds);
+
+  return shell_cmd_id;
+}
+
+/********************************************************************
+ * - Add a command to Shell environment: write_unique_blocks
+ * - Add associated options
+ * - Add command dependency
+ *******************************************************************/
+template <class T>
+ShellCommandId add_write_unique_blocks_command_template(
+  openfpga::Shell<T>& shell, const ShellCommandClassId& cmd_class_id,
+  const std::vector<ShellCommandId>& dependent_cmds, const bool& hidden) {
+  Command shell_cmd("write_unique_blocks");
+
+  /* Add an option '--file' */
+  CommandOptionId opt_file =
+    shell_cmd.add_option("file", true, "specify the unique blocks xml file");
+  shell_cmd.set_option_require_value(opt_file, openfpga::OPT_STRING);
+
+  /* Add an option '--type' */
+  CommandOptionId opt_type = shell_cmd.add_option(
+    "type", true, "specify the type of the unique blocks xml file");
+  shell_cmd.set_option_require_value(opt_type, openfpga::OPT_STRING);
+
+  /* Add an option '--verbose' */
+  shell_cmd.add_option("verbose", false, "Show verbose outputs");
+
+  /* Add command 'compact_routing_hierarchy' to the Shell */
+  ShellCommandId shell_cmd_id =
+    shell.add_command(shell_cmd, "Preload unique blocks from xml file", hidden);
+  shell.set_command_class(shell_cmd_id, cmd_class_id);
+  shell.set_command_execute_function(shell_cmd_id,
+                                     write_unique_blocks_template<T>);
+
+  /* Add command dependency to the Shell */
+  shell.set_command_dependency(shell_cmd_id, dependent_cmds);
+
+  return shell_cmd_id;
+}
+
 template <class T>
 void add_setup_command_templates(openfpga::Shell<T>& shell,
                                  const bool& hidden = false) {
@@ -1181,8 +1259,21 @@ void add_setup_command_templates(openfpga::Shell<T>& shell,
   add_write_fabric_pin_physical_location_command_template<T>(
     shell, openfpga_setup_cmd_class,
     cmd_dependency_write_fabric_pin_physical_location, hidden);
-}
 
+  /********************************
+   * Command 'read_unique_blocks'
+   */
+  add_read_unique_blocks_command_template<T>(
+    shell, openfpga_setup_cmd_class, std::vector<openfpga::ShellCommandId>(),
+    hidden);
+
+  /********************************
+   * Command 'write_unique_blocks'
+   */
+  add_write_unique_blocks_command_template<T>(
+    shell, openfpga_setup_cmd_class, std::vector<openfpga::ShellCommandId>(),
+    hidden);
+}
 } /* end namespace openfpga */
 
 #endif
diff --git a/openfpga/src/fabric/read_write_xml_unique_blocks.h b/openfpga/src/fabric/read_write_xml_unique_blocks.h
new file mode 100644
index 000000000..e3ab6cb90
--- /dev/null
+++ b/openfpga/src/fabric/read_write_xml_unique_blocks.h
@@ -0,0 +1,300 @@
+#ifndef READ_WRITE_XML_UNIQUE_BLOCKS_H
+#define READ_WRITE_XML_UNIQUE_BLOCKS_H
+
+/********************************************************************
+ * This file includes the top-level function of this library
+ * which reads an XML of unique routing blocks to the associated
+ * data structures device_rr_gsb
+ *******************************************************************/
+
+#include <string>
+
+/* Headers from pugi XML library */
+#include "pugixml.hpp"
+#include "pugixml_util.hpp"
+
+/* Headers from vtr util library */
+#include "vtr_assert.h"
+#include "vtr_log.h"
+#include "vtr_time.h"
+
+/* Headers from libopenfpga util library */
+#include "openfpga_port_parser.h"
+
+/* Headers from libarchfpga */
+#include "arch_error.h"
+#include "device_rr_gsb_utils.h"
+#include "openfpga_digest.h"
+#include "read_write_xml_unique_blocks.h"
+#include "read_xml_util.h"
+#include "rr_gsb.h"
+#include "write_xml_utils.h"
+
+/********************************************************************
+ * Parse XML codes of a <instance> to an object of device_rr_gsb
+ * instance is the mirror module of unique module.
+ *******************************************************************/
+vtr::Point<size_t> read_xml_unique_instance_info(
+  pugi::xml_node& xml_instance_info, const pugiutil::loc_data& loc_data) {
+  int instance_x = get_attribute(xml_instance_info, "x", loc_data).as_int();
+  int instance_y = get_attribute(xml_instance_info, "y", loc_data).as_int();
+  vtr::Point<size_t> instance_coordinate(instance_x, instance_y);
+  return instance_coordinate;
+}
+
+template <class T>
+void report_unique_module_status_read(T& openfpga_ctx, bool verbose_output) {
+  /* Report the stats */
+  VTR_LOGV(
+    verbose_output,
+    "Read %lu unique X-direction connection blocks ",
+    openfpga_ctx.device_rr_gsb().get_num_cb_unique_module(CHANX));
+
+  VTR_LOGV(
+    verbose_output,
+    "Read %lu unique Y-direction connection blocks from a total of %d "
+    "(compression rate=%.2f%)\n",
+    openfpga_ctx.device_rr_gsb().get_num_cb_unique_module(CHANY),
+    find_device_rr_gsb_num_cb_modules(openfpga_ctx.device_rr_gsb(), CHANY),
+    100. *
+      ((float)find_device_rr_gsb_num_cb_modules(openfpga_ctx.device_rr_gsb(),
+                                                CHANY) /
+         (float)openfpga_ctx.device_rr_gsb().get_num_cb_unique_module(CHANY) -
+       1.));
+
+  VTR_LOGV(
+    verbose_output,
+    "Read %lu unique switch blocks from a total of %d (compression "
+    "rate=%.2f%)\n",
+    openfpga_ctx.device_rr_gsb().get_num_sb_unique_module(),
+    find_device_rr_gsb_num_sb_modules(openfpga_ctx.device_rr_gsb(),
+                                      g_vpr_ctx.device().rr_graph),
+    100. * ((float)find_device_rr_gsb_num_sb_modules(
+              openfpga_ctx.device_rr_gsb(), g_vpr_ctx.device().rr_graph) /
+              (float)openfpga_ctx.device_rr_gsb().get_num_sb_unique_module() -
+            1.));
+
+  VTR_LOG(
+    "Read %lu unique general switch blocks from a total of %d "
+    "(compression "
+    "rate=%.2f%)\n",
+    openfpga_ctx.device_rr_gsb().get_num_gsb_unique_module(),
+    find_device_rr_gsb_num_gsb_modules(openfpga_ctx.device_rr_gsb(),
+                                       g_vpr_ctx.device().rr_graph),
+    100. * ((float)find_device_rr_gsb_num_gsb_modules(
+              openfpga_ctx.device_rr_gsb(), g_vpr_ctx.device().rr_graph) /
+              (float)openfpga_ctx.device_rr_gsb().get_num_gsb_unique_module() -
+            1.));
+}
+
+
+template <class T>
+void report_unique_module_status_write(T& openfpga_ctx, bool verbose_output) {
+  /* Report the stats */
+  VTR_LOGV(
+    verbose_output,
+    "Write %lu unique X-direction connection blocks from a total of %d "
+    "(compression rate=%.2f%)\n",
+    openfpga_ctx.device_rr_gsb().get_num_cb_unique_module(CHANX),
+    find_device_rr_gsb_num_cb_modules(openfpga_ctx.device_rr_gsb(), CHANX),
+    100. *
+      ((float)find_device_rr_gsb_num_cb_modules(openfpga_ctx.device_rr_gsb(),
+                                                CHANX) /
+         (float)openfpga_ctx.device_rr_gsb().get_num_cb_unique_module(CHANX) -
+       1.));
+
+  VTR_LOGV(
+    verbose_output,
+    "Write %lu unique Y-direction connection blocks from a total of %d "
+    "(compression rate=%.2f%)\n",
+    openfpga_ctx.device_rr_gsb().get_num_cb_unique_module(CHANY),
+    find_device_rr_gsb_num_cb_modules(openfpga_ctx.device_rr_gsb(), CHANY),
+    100. *
+      ((float)find_device_rr_gsb_num_cb_modules(openfpga_ctx.device_rr_gsb(),
+                                                CHANY) /
+         (float)openfpga_ctx.device_rr_gsb().get_num_cb_unique_module(CHANY) -
+       1.));
+
+  VTR_LOGV(
+    verbose_output,
+    "Write %lu unique switch blocks from a total of %d (compression "
+    "rate=%.2f%)\n",
+    openfpga_ctx.device_rr_gsb().get_num_sb_unique_module(),
+    find_device_rr_gsb_num_sb_modules(openfpga_ctx.device_rr_gsb(),
+                                      g_vpr_ctx.device().rr_graph),
+    100. * ((float)find_device_rr_gsb_num_sb_modules(
+              openfpga_ctx.device_rr_gsb(), g_vpr_ctx.device().rr_graph) /
+              (float)openfpga_ctx.device_rr_gsb().get_num_sb_unique_module() -
+            1.));
+
+  VTR_LOG(
+    "Write %lu unique general switch blocks from a total of %d "
+    "(compression "
+    "rate=%.2f%)\n",
+    openfpga_ctx.device_rr_gsb().get_num_gsb_unique_module(),
+    find_device_rr_gsb_num_gsb_modules(openfpga_ctx.device_rr_gsb(),
+                                       g_vpr_ctx.device().rr_graph),
+    100. * ((float)find_device_rr_gsb_num_gsb_modules(
+              openfpga_ctx.device_rr_gsb(), g_vpr_ctx.device().rr_graph) /
+              (float)openfpga_ctx.device_rr_gsb().get_num_gsb_unique_module() -
+            1.));
+}
+/********************************************************************
+ * Parse XML codes about <unique_blocks> to an object of device_rr_gsb
+ *******************************************************************/
+template <class T>
+int read_xml_unique_blocks(T& openfpga_ctx, const char* file_name,
+                           const char* file_type, bool verbose_output) {
+  vtr::ScopedStartFinishTimer timer("Read unique blocks xml file");
+  /* Parse the file */
+  pugi::xml_document doc;
+  pugiutil::loc_data loc_data;
+  VTR_ASSERT(strcmp(file_type, "xml") == 0);
+  try {
+    loc_data = pugiutil::load_xml(doc, file_name);
+
+    pugi::xml_node xml_root = get_single_child(doc, "unique_blocks", loc_data);
+
+    /* get device_rr_gsb data type and initialize it*/
+    openfpga::DeviceRRGSB& device_rr_gsb = openfpga_ctx.mutable_device_rr_gsb();
+    /* clear unique modules */
+    device_rr_gsb.clear_unique_modules();
+     vtr::Point<size_t> grid_coord(g_vpr_ctx.device().grid.width() - 1,
+                               g_vpr_ctx.device().grid.height() - 1);
+    device_rr_gsb.reserve_unique_modules(grid_coord);
+    /* load unique blocks xml file and set up device_rr_gdb */
+    for (pugi::xml_node xml_block_info : xml_root.children()) {
+      /* Error out if the XML child has an invalid name! */
+      if (xml_block_info.name() == std::string("block")) {
+        std::string type =
+          get_attribute(xml_block_info, "type", loc_data).as_string();
+        int block_x = get_attribute(xml_block_info, "x", loc_data).as_int();
+        int block_y = get_attribute(xml_block_info, "y", loc_data).as_int();
+        vtr::Point<size_t> block_coordinate(block_x, block_y);
+        std::vector<vtr::Point<size_t>> instance_coords;
+        for (pugi::xml_node xml_instance_info : xml_block_info.children()) {
+          if (xml_instance_info.name() == std::string("instance")) {
+            auto instance_coordinate =
+              read_xml_unique_instance_info(xml_instance_info, loc_data);
+            instance_coords.push_back(instance_coordinate);
+          }
+        }
+        /* get block coordinate and instance coordinate, try to setup device rr
+         * gsb */
+        if (type == "sb") {
+          device_rr_gsb.preload_unique_sb_module(block_coordinate,
+                                                 instance_coords);
+        } else if (type == "cby") {
+          device_rr_gsb.preload_unique_cby_module(block_coordinate,
+                                                 instance_coords);
+        } else if (type == "cbx") {
+          device_rr_gsb.preload_unique_cbx_module(block_coordinate,
+                                                 instance_coords);
+        } else {
+          VTR_LOG_ERROR("Unexpected type!");
+        }
+      } else {
+        bad_tag(xml_block_info, loc_data, xml_root, {"block"});
+        return 1;
+      }
+    }
+    device_rr_gsb.build_gsb_unique_module();
+    if (verbose_output) {
+      report_unique_module_status_read(openfpga_ctx, true);
+    }
+  } catch (pugiutil::XmlError& e) {
+    archfpga_throw(file_name, e.line(), "%s", e.what());
+  }
+  
+  return 0;
+}
+
+int write_xml_block(
+  std::map<int, vtr::Point<size_t>>& id_unique_block_map,
+  std::map<int, std::vector<vtr::Point<size_t>>>& id_instance_map,
+  std::fstream& fp, std::string type) {
+  /* Validate the file stream */
+  if (false == openfpga::valid_file_stream(fp)) {
+    return 2;
+  }
+  for (const auto& pair : id_unique_block_map) {
+    openfpga::write_tab_to_file(fp, 1);
+    fp << "<block";
+    write_xml_attribute(fp, "type", type.c_str());
+    write_xml_attribute(fp, "x", pair.second.x());
+    write_xml_attribute(fp, "y", pair.second.y());
+
+    fp << ">"
+       << "\n";
+
+    for (const auto& instance_info : id_instance_map[pair.first]) {
+      if (instance_info.x() == pair.second.x() &&
+          instance_info.y() == pair.second.y()) {
+            ;  
+      }else{
+        openfpga::write_tab_to_file(fp, 2);
+        fp << "<instance";
+        write_xml_attribute(fp, "x", instance_info.x());
+        write_xml_attribute(fp, "y", instance_info.y());
+
+        fp << "/>"
+           << "\n";
+      }
+    }
+    openfpga::write_tab_to_file(fp, 1);
+    fp << "</block>"
+       << "\n";
+  }
+
+  return 0;
+}
+
+template <class T>
+int write_xml_unique_blocks(const T& openfpga_ctx, const char* fname,
+                            const char* file_type, bool verbose_output) {
+  vtr::ScopedStartFinishTimer timer("Write unique blocks...");
+  VTR_ASSERT(strcmp(file_type, "xml") == 0);
+  /* Create a file handler */
+  std::fstream fp;
+  /* Open the file stream */
+  fp.open(std::string(fname), std::fstream::out | std::fstream::trunc);
+
+  /* Validate the file stream */
+  openfpga::check_file_stream(fname, fp);
+
+  /* Write the root node */
+  fp << "<unique_blocks>"
+     << "\n";
+
+  int err_code = 0;
+  std::map<int, vtr::Point<size_t>> id_unique_block_map;
+  std::map<int, std::vector<vtr::Point<size_t>>> id_instance_map;
+  openfpga_ctx.device_rr_gsb().get_id_unique_sb_block_map(id_unique_block_map);
+  openfpga_ctx.device_rr_gsb().get_id_sb_instance_map(id_instance_map);
+  err_code += write_xml_block(id_unique_block_map, id_instance_map, fp, "sb");
+
+  id_unique_block_map.clear();
+  id_instance_map.clear();
+  openfpga_ctx.device_rr_gsb().get_id_unique_cbx_block_map(id_unique_block_map);
+  openfpga_ctx.device_rr_gsb().get_id_cbx_instance_map(id_instance_map);
+  err_code += write_xml_block(id_unique_block_map, id_instance_map, fp, "cbx");
+
+  id_unique_block_map.clear();
+  id_instance_map.clear();
+  openfpga_ctx.device_rr_gsb().get_id_unique_cby_block_map(id_unique_block_map);
+  openfpga_ctx.device_rr_gsb().get_id_cby_instance_map(id_instance_map);
+  err_code += write_xml_block(id_unique_block_map, id_instance_map, fp, "cby");
+
+  /* Finish writing the root node */
+  fp << "</unique_blocks>"
+     << "\n";
+
+  /* Close the file stream */
+  fp.close();
+  if (verbose_output) {
+    report_unique_module_status_write(openfpga_ctx, true);
+  }
+  return err_code;
+}
+
+#endif