[vpr][place] use a constexpr to compare the number of blocks in column

Author: amin1377

vpr/src/place/move_utils.cpp

@@ -19,6 +19,8 @@
 //Note: The flag is only effective if compiled with VTR_ENABLE_DEBUG_LOGGING
 bool f_placer_breakpoint_reached = false;
 
+constexpr int MIN_NUMBER_OF_BLOCK_PER_COLUMN = 3;
+
 //Accessor for f_placer_breakpoint_reached
 bool placer_breakpoint_reached() {
     return f_placer_breakpoint_reached;
@@ -1017,7 +1019,7 @@ bool find_compatible_compressed_loc_in_range(t_logical_block_type_ptr type,
         }
         auto y_upper_iter = block_rows.upper_bound(search_range.ymax);
 
-        if (block_rows.size() < 3) {
+        if (block_rows.size() < MIN_NUMBER_OF_BLOCK_PER_COLUMN && !block_constrained) {
             //Fall back to allow the whole y range
             y_lower_iter = block_rows.begin();
             y_upper_iter = block_rows.end();