Added comments and add unit test to check macro routine that updates member PartitionRegions

Author: sfkhalid

vpr/src/place/initial_placement.cpp

@@ -419,8 +419,8 @@ void initial_placement(enum e_pad_loc_type pad_loc_type, const char* constraints
     vtr::vector<ClusterBlockId, t_block_score> block_scores = assign_block_scores();
     std::vector<ClusterBlockId> sorted_blocks = sort_blocks(block_scores);
 
-    //Perform constraints_propagation
-    constraints_propagation();
+    //Go through blocks with floorplan constraints to ensure we have the tightest constraint on each one.
+    propagate_place_constraints();
 
     // Loading legal placement locations
     zero_initialize_grid_blocks();

vpr/src/place/place_constraints.cpp

@@ -142,7 +142,7 @@ PartitionRegion update_macro_member_pr(PartitionRegion& head_pr, const t_pl_offs
     return macro_pr;
 }
 
-void constraints_propagation() {
+void propagate_place_constraints() {
     auto& place_ctx = g_vpr_ctx.placement();
     auto& floorplanning_ctx = g_vpr_ctx.mutable_floorplanning();
 

vpr/src/place/place_constraints.h

@@ -40,7 +40,12 @@ bool is_macro_constrained(const t_pl_macro& pl_macro);
 PartitionRegion update_macro_head_pr(const t_pl_macro& pl_macro);
 
 /*
- * Update macro member PR
+ * Update the PartitionRegions of non-head members of a macro,
+ * based on the constraint that was calculated for the head region.
+ * The constraint that was calculated for the head region considered all
+ * constrained blocks in the macro, so to calculate the constraint for the rest
+ * of the blocks, it is just the head constraint with the offset of the member
+ * applied.
  */
 PartitionRegion update_macro_member_pr(PartitionRegion& head_pr, const t_pl_offset& offset);
 
@@ -51,7 +56,7 @@ PartitionRegion update_macro_member_pr(PartitionRegion& head_pr, const t_pl_offs
  * This is done at the start of initial placement to ease floorplan legality checking
  * while placing macros during initial placement.
  */
-void constraints_propagation();
+void propagate_place_constraints();
 
 inline bool floorplan_legal(const t_pl_blocks_to_be_moved& blocks_affected) {
     bool floorplan_legal;

vpr/test/test_vpr_constraints.cpp

@@ -6,6 +6,7 @@
 #include "vpr_constraints.h"
 #include "partition.h"
 #include "region.h"
+#include "place_constraints.h"
 
 /**
  * This file contains unit tests that check the functionality of all classes related to vpr constraints. These classes include
@@ -425,6 +426,28 @@ TEST_CASE("RegionLocked", "[vpr]") {
     REQUIRE(is_r2_locked == false);
 }
 
+//Test calculation of macro constraints
+TEST_CASE("MacroConstraints", "[vpr]") {
+    PartitionRegion head_pr;
+    t_pl_offset offset(2, 1, 0);
+
+    Region reg;
+    reg.set_region_rect(5, 2, 9, 6);
+
+    head_pr.add_to_part_region(reg);
+
+    PartitionRegion macro_pr = update_macro_member_pr(head_pr, offset);
+
+    std::vector<Region> mac_regions = macro_pr.get_partition_region();
+
+    vtr::Rect<int> mac_rect = mac_regions[0].get_region_rect();
+
+    REQUIRE(mac_rect.xmin() == 7);
+    REQUIRE(mac_rect.ymin() == 3);
+    REQUIRE(mac_rect.xmax() == 11);
+    REQUIRE(mac_rect.ymax() == 7);
+}
+
 static constexpr const char kArchFile[] = "test_read_arch_metadata.xml";
 
 // Test that place constraints are not changed during placement