remove place_cost_exp from docs

Author: soheilshahrouz

doc/src/vpr/command_line_usage.rst

@@ -868,14 +868,6 @@ Setting any of the following 5 options selects :ref:`Dusty's annealing schedule
 
     **Default:** ``0.25``
 
-.. option:: --place_cost_exp <float>
-
-    Wiring cost is divided by the average channel width over a net's bounding box
-    taken to this exponent. Only impacts devices with different channel widths in 
-    different directions or regions. 
-
-    **Default:** ``1``
-
 .. option:: --RL_agent_placement {on | off}
 
     Uses a Reinforcement Learning (RL) agent in choosing the appropiate move type in placement.

vpr/src/base/vpr_types.h

@@ -991,11 +991,6 @@ enum class e_move_type;
  *   @param timing_tradeoff
  *              When in CRITICALITY_TIMING_PLACE mode, what is the
  *              tradeoff between timing and wiring costs.
- *   @param place_cost_exp
- *              Wiring cost is divided by the average channel width over
- *              a net's bounding box taken to this exponent.
- *              Only impacts devices with different channel widths in 
- *              different directions or regions. (Default: 1)
  *   @param place_chan_width
  *              The channel width assumed if only one placement is performed.
  *   @param pad_loc_type

vpr/src/place/net_cost_handler.h

@@ -253,17 +253,15 @@ class NetCostHandler {
      * @details This is only useful for the cost function that takes the length of the net bounding box in each
      * dimension divided by the average number of tracks in that direction. For other cost functions, you don't
      * have to bother calling this routine; when using the cost function described above, however, you must always
-     * call this routine before you do any placement cost determination. The place_cost_exp factor specifies to
-     * what power the width of the channel should be taken -- larger numbers make narrower channels more expensive.
+     * call this routine before you do any placement cost determination.
      */
     void alloc_and_load_chan_w_factors_for_place_cost_();
 
     /**
     * @brief Allocates and loads acc_tile_num_inter_die_conn_ which contains the accumulative number of inter-die
     * conntections.
     *
-    * @details This is only useful for multi-die FPGAs. The place_cost_exp factor specifies to
-    * what power the average number of inter-die connections should be take -- larger numbers make narrower channels more expensive.
+    * @details This is only useful for multi-die FPGAs.
     */
     void alloc_and_load_for_fast_vertical_cost_update_();