Merge pull request #1751 from verilog-to-routing/constraints_propagation

Add constraints propagation to update the PartitionRegions of blocks …

Author: vaughnbetz

vpr/src/place/initial_placement.cpp

@@ -82,20 +82,22 @@ static int check_macro_can_be_placed(t_pl_macro pl_macro, int itype, t_pl_loc he
     // Every macro can be placed until proven otherwise
     int macro_can_be_placed = true;
 
+    //Check whether macro contains blocks with floorplan constraints
     bool macro_constrained = is_macro_constrained(pl_macro);
-    PartitionRegion macro_pr;
-
-    if (macro_constrained) {
-        macro_pr = constrained_macro_locs(pl_macro);
-    }
 
     // Check whether all the members can be placed
     for (size_t imember = 0; imember < pl_macro.members.size(); imember++) {
         t_pl_loc member_pos = head_pos + pl_macro.members[imember].offset;
 
-        //if the macro is constrained, check if the member position is within the PartitionRegion for the macro
-        if (macro_constrained) {
-            bool member_loc_good = macro_pr.is_loc_in_part_reg(member_pos);
+        /*
+         * If the macro is constrained, check that the head member is in a legal position from
+         * a floorplanning perspective. It is enough to do this check for the head member alone,
+         * because constraints propagation was performed to calculate smallest floorplan region for the head
+         * macro, based on the constraints on all of the blocks in the macro. So, if the head macro is in a
+         * legal floorplan location, all other blocks in the macro will be as well.
+         */
+        if (macro_constrained && imember == 0) {
+            bool member_loc_good = cluster_floorplanning_legal(pl_macro.members[imember].blk_index, member_pos);
             if (!member_loc_good) {
                 macro_can_be_placed = false;
                 break;
@@ -417,6 +419,11 @@ 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);
 
+    /* Go through cluster blocks to calculate the tightest placement
+     * floorplan constraint for each constrained block
+     */
+    propagate_place_constraints();
+
     // Loading legal placement locations
     zero_initialize_grid_blocks();
     alloc_and_load_legal_placement_locations(legal_pos);

vpr/src/place/place_constraints.cpp

@@ -54,8 +54,8 @@ bool is_macro_constrained(const t_pl_macro& pl_macro) {
 }
 
 /*Returns PartitionRegion of where the head of the macro could go*/
-PartitionRegion constrained_macro_locs(const t_pl_macro& pl_macro) {
-    PartitionRegion macro_pr;
+PartitionRegion update_macro_head_pr(const t_pl_macro& pl_macro, const PartitionRegion& grid_pr) {
+    PartitionRegion macro_head_pr;
     bool is_member_constrained = false;
     int num_constrained_members = 0;
     auto& floorplanning_ctx = g_vpr_ctx.floorplanning();
@@ -80,39 +80,116 @@ PartitionRegion constrained_macro_locs(const t_pl_macro& pl_macro) {
 
                 vtr::Rect<int> reg_rect = block_regions[i].get_region_rect();
 
-                t_pl_loc min_pl_loc(reg_rect.xmin(), reg_rect.ymin(), block_regions[i].get_sub_tile());
-
-                t_pl_loc modified_min_pl_loc = min_pl_loc + offset;
-
-                t_pl_loc max_pl_loc(reg_rect.xmax(), reg_rect.ymax(), block_regions[i].get_sub_tile());
+                modified_reg.set_region_rect(reg_rect.xmin() - offset.x, reg_rect.ymin() - offset.y, reg_rect.xmax() - offset.x, reg_rect.ymax() - offset.y);
 
-                t_pl_loc modified_max_pl_loc = max_pl_loc + offset;
-
-                modified_reg.set_region_rect(modified_min_pl_loc.x, modified_min_pl_loc.y, modified_max_pl_loc.x, modified_max_pl_loc.y);
                 //check that subtile is not an invalid value before changing, otherwise it just stays -1
-                if (block_regions[i].get_sub_tile() != -1) {
-                    modified_reg.set_sub_tile(modified_min_pl_loc.sub_tile);
+                if (block_regions[i].get_sub_tile() != NO_SUBTILE) {
+                    modified_reg.set_sub_tile(block_regions[i].get_sub_tile() - offset.sub_tile);
                 }
 
                 modified_pr.add_to_part_region(modified_reg);
             }
 
             if (num_constrained_members == 1) {
-                macro_pr = modified_pr;
+                macro_head_pr = modified_pr;
             } else {
-                macro_pr = intersection(macro_pr, modified_pr);
+                macro_head_pr = intersection(macro_head_pr, modified_pr);
             }
         }
     }
 
+    //intersect to ensure the head pr does not go outside of grid dimensions
+    macro_head_pr = intersection(macro_head_pr, grid_pr);
+
+    //if the intersection is empty, no way to place macro members together, give an error
+    if (macro_head_pr.empty()) {
+        print_macro_constraint_error(pl_macro);
+    }
+
+    return macro_head_pr;
+}
+
+PartitionRegion update_macro_member_pr(PartitionRegion& head_pr, const t_pl_offset& offset, const PartitionRegion& grid_pr, const t_pl_macro& pl_macro) {
+    std::vector<Region> block_regions = head_pr.get_partition_region();
+    PartitionRegion macro_pr;
+
+    for (unsigned int i = 0; i < block_regions.size(); i++) {
+        Region modified_reg;
+
+        vtr::Rect<int> reg_rect = block_regions[i].get_region_rect();
+
+        modified_reg.set_region_rect(reg_rect.xmin() + offset.x, reg_rect.ymin() + offset.y, reg_rect.xmax() + offset.x, reg_rect.ymax() + offset.y);
+
+        //check that subtile is not an invalid value before changing, otherwise it just stays -1
+        if (block_regions[i].get_sub_tile() != NO_SUBTILE) {
+            modified_reg.set_sub_tile(block_regions[i].get_sub_tile() + offset.sub_tile);
+        }
+
+        macro_pr.add_to_part_region(modified_reg);
+    }
+
+    //intersect to ensure the macro pr does not go outside of grid dimensions
+    macro_pr = intersection(macro_pr, grid_pr);
+
     //if the intersection is empty, no way to place macro members together, give an error
     if (macro_pr.empty()) {
-        VPR_ERROR(VPR_ERROR_PLACE, " \n Feasible floorplanning constraints could not be calculated for the placement macro.\n");
+        print_macro_constraint_error(pl_macro);
     }
 
     return macro_pr;
 }
 
+void print_macro_constraint_error(const t_pl_macro& pl_macro) {
+    auto& cluster_ctx = g_vpr_ctx.clustering();
+    VTR_LOG(
+        "Feasible floorplanning constraints could not be calculated for the placement macro. \n"
+        "The placement macro contains the following blocks: \n");
+    for (unsigned int i = 0; i < pl_macro.members.size(); i++) {
+        std::string blk_name = cluster_ctx.clb_nlist.block_name((pl_macro.members[i].blk_index));
+        VTR_LOG("Block %s (#%zu) ", blk_name.c_str(), size_t(pl_macro.members[i].blk_index));
+    }
+    VTR_LOG("\n");
+    VPR_ERROR(VPR_ERROR_PLACE, " \n Check that the above-mentioned placement macro blocks have compatible floorplan constraints.\n");
+}
+
+void propagate_place_constraints() {
+    auto& place_ctx = g_vpr_ctx.placement();
+    auto& floorplanning_ctx = g_vpr_ctx.mutable_floorplanning();
+    auto& device_ctx = g_vpr_ctx.device();
+
+    //Create a PartitionRegion with grid dimensions
+    //Will be used to check that updated PartitionRegions are within grid bounds
+    int width = device_ctx.grid.width() - 1;
+    int height = device_ctx.grid.height() - 1;
+    Region grid_reg;
+    grid_reg.set_region_rect(0, 0, width, height);
+    PartitionRegion grid_pr;
+    grid_pr.add_to_part_region(grid_reg);
+
+    for (auto pl_macro : place_ctx.pl_macros) {
+        if (is_macro_constrained(pl_macro)) {
+            /*
+             * Get the PartitionRegion for the head of the macro
+             * based on the constraints of all blocks contained in the macro
+             */
+            PartitionRegion macro_head_pr = update_macro_head_pr(pl_macro, grid_pr);
+
+            //Update PartitionRegions of all members of the macro
+            for (size_t imember = 0; imember < pl_macro.members.size(); imember++) {
+                ClusterBlockId iblk = pl_macro.members[imember].blk_index;
+                auto offset = pl_macro.members[imember].offset;
+
+                if (imember == 0) { //Update head PR
+                    floorplanning_ctx.cluster_constraints[iblk] = macro_head_pr;
+                } else { //Update macro member PR
+                    PartitionRegion macro_pr = update_macro_member_pr(macro_head_pr, offset, grid_pr, pl_macro);
+                    floorplanning_ctx.cluster_constraints[iblk] = macro_pr;
+                }
+            }
+        }
+    }
+}
+
 /*returns true if location is compatible with floorplanning constraints, false if not*/
 /*
  * Even if the block passed in is from a macro, it will work because of the constraints

vpr/src/place/place_constraints.h

@@ -34,9 +34,33 @@ bool cluster_floorplanning_legal(ClusterBlockId blk_id, const t_pl_loc& loc);
 bool is_macro_constrained(const t_pl_macro& pl_macro);
 
 /*
- * Returns region of valid locations for the head of the macro based on floorplan constraints
+ * Returns PartitionRegion for the head of the macro based on the floorplan constraints
+ * of all blocks in the macro. For example, if there was a macro of length two and each block has
+ * a constraint, this routine will shift and intersect the two constraint regions to calculate
+ * the tightest region constraint for the head macro.
  */
-PartitionRegion constrained_macro_locs(const t_pl_macro& pl_macro);
+PartitionRegion update_macro_head_pr(const t_pl_macro& pl_macro, const PartitionRegion& grid_pr);
+
+/*
+ * Update the PartitionRegions of non-head members of a macro,
+ * based on the constraint that was calculated for the head region, head_pr.
+ * The constraint on the head region must be the tightest possible (i.e. implied by the
+ * entire macro) before this routine is called.
+ * For each macro member, the updated constraint is essentially the head constraint
+ * with the member's offset applied.
+ */
+PartitionRegion update_macro_member_pr(PartitionRegion& head_pr, const t_pl_offset& offset, const PartitionRegion& grid_pr, const t_pl_macro& pl_macro);
+
+/*
+ * Updates the floorplan constraints information for all constrained macros.
+ * Updates the constraints to be the tightest constraints possible while adhering
+ * to the floorplan constraints of each macro member.
+ * This is done at the start of initial placement to ease floorplan legality checking
+ * while placing macros during initial placement.
+ */
+void propagate_place_constraints();
+
+void print_macro_constraint_error(const t_pl_macro& pl_macro);
 
 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 +426,37 @@ TEST_CASE("RegionLocked", "[vpr]") {
     REQUIRE(is_r2_locked == false);
 }
 
+//Test calculation of macro constraints
+/* Checks that the PartitionRegion of a macro member is updated properly according
+ * to the head member's PartitionRegion that is passed in.
+ */
+TEST_CASE("MacroConstraints", "[vpr]") {
+    t_pl_macro pl_macro;
+    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);
+
+    Region grid_reg;
+    grid_reg.set_region_rect(0, 0, 20, 20);
+    PartitionRegion grid_pr;
+    grid_pr.add_to_part_region(grid_reg);
+
+    PartitionRegion macro_pr = update_macro_member_pr(head_pr, offset, grid_pr, pl_macro);
+
+    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