Integrating SA placer and legaliser

Signed-off-by: David Shah <davey1576@gmail.com>

2 files changed, 38 insertions, 10 deletions

diff --git a/common/place_common.cc b/common/place_common.cc
index 591985f1..12345a89 100644
--- a/common/place_common.cc
+++ b/common/place_common.cc
@@ -21,6 +21,7 @@
 #include <cmath>
 #include "log.h"
 #include "util.h"
+
 NEXTPNR_NAMESPACE_BEGIN
 
 // Get the total estimated wirelength for a net
@@ -118,12 +119,16 @@ bool place_single_cell(Context *ctx, CellInfo *cell, bool require_legality)
             if (ctx->getBelType(bel) == targetType && (!require_legality || ctx->isValidBelForCell(cell, bel))) {
                 if (ctx->checkBelAvail(bel)) {
                     wirelen_t wirelen = get_cell_wirelength_at_bel(ctx, cell, bel);
+                    if (wirelen == 0)
+                        wirelen = ctx->rng(100);
                     if (wirelen <= best_wirelen) {
                         best_wirelen = wirelen;
                         best_bel = bel;
                     }
                 } else {
                     wirelen_t wirelen = get_cell_wirelength_at_bel(ctx, cell, bel);
+                    if (wirelen == 0)
+                        wirelen = ctx->rng(100);
                     if (wirelen <= best_ripup_wirelen) {
                         ripup_target = ctx->cells.at(ctx->getBoundBelCell(bel)).get();
                         if (ripup_target->belStrength < STRENGTH_STRONG) {
@@ -135,7 +140,11 @@ bool place_single_cell(Context *ctx, CellInfo *cell, bool require_legality)
             }
         }
         if (best_bel == BelId()) {
-            if (iters == 0 || ripup_bel == BelId()) {
+            if (iters == 0) {
+                log_error("failed to place cell '%s' of type '%s' (ripup iteration limit exceeded)\n",
+                          cell->name.c_str(ctx), cell->type.c_str(ctx));
+            }
+            if (ripup_bel == BelId()) {
                 log_error("failed to place cell '%s' of type '%s'\n", cell->name.c_str(ctx), cell->type.c_str(ctx));
             }
             --iters;
diff --git a/common/place_sa.cc b/common/place_sa.cc
index ed584d60..d8ab24ce 100644
--- a/common/place_sa.cc
+++ b/common/place_sa.cc
@@ -38,7 +38,8 @@
 #include <vector>
 #include "log.h"
 #include "place_common.h"
-
+#include "place_legaliser.h"
+#include "util.h"
 NEXTPNR_NAMESPACE_BEGIN
 
 class SAPlacer
@@ -206,6 +207,17 @@ class SAPlacer
                 }
             }
 
+            if (temp < legalise_temp && !require_legal) {
+                legalise_design(ctx);
+                require_legal = true;
+                autoplaced.clear();
+                for (auto cell : sorted(ctx->cells)) {
+                    if (cell.second->belStrength < STRENGTH_STRONG)
+                        autoplaced.push_back(cell.second);
+                }
+                ctx->shuffle(autoplaced);
+            }
+
             // Recalculate total wirelength entirely to avoid rounding errors
             // accumulating over time
             curr_wirelength = 0;
@@ -254,7 +266,7 @@ class SAPlacer
             }
             BelType targetType = ctx->belTypeFromId(cell->type);
             for (auto bel : ctx->getBels()) {
-                if (ctx->getBelType(bel) == targetType && ctx->isValidBelForCell(cell, bel)) {
+                if (ctx->getBelType(bel) == targetType && (ctx->isValidBelForCell(cell, bel) || !require_legal)) {
                     if (ctx->checkBelAvail(bel)) {
                         uint64_t score = ctx->rng64();
                         if (score <= best_score) {
@@ -298,10 +310,14 @@ class SAPlacer
         BelId oldBel = cell->bel;
         IdString other = ctx->getBoundBelCell(newBel);
         CellInfo *other_cell = nullptr;
+        if (other != IdString()) {
+            other_cell = ctx->cells[other].get();
+            if (other_cell->belStrength > STRENGTH_WEAK)
+                return false;
+        }
         wirelen_t new_wirelength = 0, delta;
         ctx->unbindBel(oldBel);
         if (other != IdString()) {
-            other_cell = ctx->cells[other].get();
             ctx->unbindBel(newBel);
         }
 
@@ -320,12 +336,13 @@ class SAPlacer
         if (other != IdString()) {
             ctx->bindBel(oldBel, other_cell->name, STRENGTH_WEAK);
         }
-
-        if (!ctx->isBelLocationValid(newBel) || ((other != IdString() && !ctx->isBelLocationValid(oldBel)))) {
-            ctx->unbindBel(newBel);
-            if (other != IdString())
-                ctx->unbindBel(oldBel);
-            goto swap_fail;
+        if (require_legal) {
+            if (!ctx->isBelLocationValid(newBel) || ((other != IdString() && !ctx->isBelLocationValid(oldBel)))) {
+                ctx->unbindBel(newBel);
+                if (other != IdString())
+                    ctx->unbindBel(oldBel);
+                goto swap_fail;
+            }
         }
 
         new_wirelength = curr_wirelength;
@@ -402,6 +419,8 @@ class SAPlacer
     std::unordered_map<BelType, int> bel_types;
     std::vector<std::vector<std::vector<std::vector<BelId>>>> fast_bels;
     std::unordered_set<BelId> locked_bels;
+    bool require_legal = false;
+    const float legalise_temp = 20;
 };
 
 bool place_design_sa(Context *ctx, bool timing_driven)