7 files changed, 111 insertions, 58 deletions
diff --git a/common/place_sa.cc b/common/place_sa.cc
index 22e750c2..12ca30d8 100644
--- a/common/place_sa.cc
+++ b/common/place_sa.cc
@@ -66,39 +66,64 @@ static float random_float_upto(rnd_state &rnd, float limit)
 
 static int random_int_between(rnd_state &rnd, int a, int b)
 {
-    return a + int(random_float_upto(rnd, b - a));
+    return a + int(random_float_upto(rnd, b - a) - 0.00001);
 }
 
 // Initial random placement
 static void place_initial(Design *design, CellInfo *cell, rnd_state &rnd)
 {
-    BelId best_bel = BelId();
-    float best_score = std::numeric_limits<float>::infinity();
-    Chip &chip = design->chip;
-    if (cell->bel != BelId()) {
-        chip.unbindBel(cell->bel);
-        cell->bel = BelId();
-    }
-    BelType targetType = belTypeFromId(cell->type);
-    for (auto bel : chip.getBels()) {
-        if (chip.getBelType(bel) == targetType && chip.checkBelAvail(bel) &&
-            isValidBelForCell(design, cell, bel)) {
-            float score = random_float_upto(rnd, 1.0);
-            if (score <= best_score) {
-                best_score = score;
-                best_bel = bel;
+    bool all_placed = false;
+    int iters = 25;
+    while (!all_placed) {
+        BelId best_bel = BelId();
+        float best_score = std::numeric_limits<float>::infinity(),
+              best_ripup_score = std::numeric_limits<float>::infinity();
+        Chip &chip = design->chip;
+        CellInfo *ripup_target = nullptr;
+        BelId ripup_bel = BelId();
+        if (cell->bel != BelId()) {
+            chip.unbindBel(cell->bel);
+            cell->bel = BelId();
+        }
+        BelType targetType = belTypeFromId(cell->type);
+        for (auto bel : chip.getBels()) {
+            if (chip.getBelType(bel) == targetType &&
+                isValidBelForCell(design, cell, bel)) {
+                if (chip.checkBelAvail(bel)) {
+                    float score = random_float_upto(rnd, 1.0);
+                    if (score <= best_score) {
+                        best_score = score;
+                        best_bel = bel;
+                    }
+                } else {
+                    float score = random_float_upto(rnd, 1.0);
+                    if (score <= best_ripup_score) {
+                        best_ripup_score = score;
+                        ripup_target =
+                                design->cells.at(chip.getBelCell(bel, true));
+                        ripup_bel = bel;
+                    }
+                }
             }
         }
-    }
-    if (best_bel == BelId()) {
-        log_error("failed to place cell '%s' of type '%s'\n",
-                  cell->name.c_str(), cell->type.c_str());
-    }
-    cell->bel = best_bel;
-    chip.bindBel(cell->bel, cell->name);
+        if (best_bel == BelId()) {
+            if (iters == 0 || ripup_bel == BelId())
+                log_error("failed to place cell '%s' of type '%s'\n",
+                          cell->name.c_str(), cell->type.c_str());
+            --iters;
+            chip.unbindBel(ripup_target->bel);
+            ripup_target->bel = BelId();
+            best_bel = ripup_bel;
+        } else {
+            all_placed = true;
+        }
+        cell->bel = best_bel;
+        chip.bindBel(cell->bel, cell->name);
 
-    // Back annotate location
-    cell->attrs["BEL"] = chip.getBelName(cell->bel).str();
+        // Back annotate location
+        cell->attrs["BEL"] = chip.getBelName(cell->bel).str();
+        cell = ripup_target;
+    }
 }
 
 // Stores the state of the SA placer
@@ -268,7 +293,7 @@ BelId random_bel_for_cell(Design *design, CellInfo *cell, SAState &state,
     }
 }
 
-void place_design_sa(Design *design)
+void place_design_sa(Design *design, int seed)
 {
     SAState state;
 
@@ -304,7 +329,7 @@ void place_design_sa(Design *design)
     }
     log_info("place_constraints placed %d\n", int(placed_cells));
     rnd_state rnd;
-    rnd.state = 1;
+    rnd.state = seed;
     std::vector<CellInfo *> autoplaced;
     // Sort to-place cells for deterministic initial placement
     for (auto cell : design->cells) {
diff --git a/common/place_sa.h b/common/place_sa.h
index f320111e..944cb97e 100644
--- a/common/place_sa.h
+++ b/common/place_sa.h
@@ -23,7 +23,7 @@
 
 NEXTPNR_NAMESPACE_BEGIN
 
-extern void place_design_sa(Design *design);
+extern void place_design_sa(Design *design, int seed);
 
 NEXTPNR_NAMESPACE_END
 
diff --git a/common/route.cc b/common/route.cc
index 32212c7d..247c8840 100644
--- a/common/route.cc
+++ b/common/route.cc
@@ -440,8 +440,8 @@ void route_design(Design *design, bool verbose)
                          "routing.\n",
                          int(netsQueue.size()));
 
-            ripup_pip_penalty += 5;
-            ripup_wire_penalty += 5;
+            ripup_pip_penalty *= 1.5;
+            ripup_wire_penalty *= 1.5;
         }
     }
 
diff --git a/ice40/arch_place.cc b/ice40/arch_place.cc
index 1c6361a1..3205fb6e 100644
--- a/ice40/arch_place.cc
+++ b/ice40/arch_place.cc
@@ -24,8 +24,8 @@
 
 NEXTPNR_NAMESPACE_BEGIN
 
-static const NetInfo *get_net_or_nullptr(const CellInfo *cell,
-                                         const IdString port)
+static const NetInfo *get_net_or_empty(const CellInfo *cell,
+                                       const IdString port)
 {
     auto found = cell->ports.find(port);
     if (found != cell->ports.end())
@@ -38,46 +38,53 @@ static bool logicCellsCompatible(const std::vector<const CellInfo *> &cells)
 {
     bool dffs_exist = false, dffs_neg = false;
     const NetInfo *cen = nullptr, *clk = nullptr, *sr = nullptr;
-    std::unordered_set<const NetInfo *> locals;
+    static std::unordered_set<IdString> locals;
+    locals.clear();
 
     for (auto cell : cells) {
         if (bool_or_default(cell->params, "DFF_ENABLE")) {
             if (!dffs_exist) {
                 dffs_exist = true;
-                cen = get_net_or_nullptr(cell, "CEN");
-                clk = get_net_or_nullptr(cell, "CLK");
-                sr = get_net_or_nullptr(cell, "SR");
+                cen = get_net_or_empty(cell, "CEN");
+                clk = get_net_or_empty(cell, "CLK");
+                sr = get_net_or_empty(cell, "SR");
 
-                if (!is_global_net(cen))
-                    locals.insert(cen);
-                if (!is_global_net(clk))
-                    locals.insert(clk);
-                if (!is_global_net(sr))
-                    locals.insert(sr);
+                if (!is_global_net(cen) && cen != nullptr)
+                    locals.insert(cen->name);
+                if (!is_global_net(clk) && clk != nullptr)
+                    locals.insert(clk->name);
+                if (!is_global_net(sr) && sr != nullptr)
+                    locals.insert(sr->name);
 
                 if (bool_or_default(cell->params, "NEG_CLK")) {
                     dffs_neg = true;
                 }
             } else {
-                if (cen != get_net_or_nullptr(cell, "CEN"))
+                if (cen != get_net_or_empty(cell, "CEN"))
                     return false;
-                if (clk != get_net_or_nullptr(cell, "CLK"))
+                if (clk != get_net_or_empty(cell, "CLK"))
                     return false;
-                if (sr != get_net_or_nullptr(cell, "SR"))
+                if (sr != get_net_or_empty(cell, "SR"))
                     return false;
                 if (dffs_neg != bool_or_default(cell->params, "NEG_CLK"))
                     return false;
             }
         }
 
-        locals.insert(get_net_or_nullptr(cell, "I0"));
-        locals.insert(get_net_or_nullptr(cell, "I1"));
-        locals.insert(get_net_or_nullptr(cell, "I2"));
-        locals.insert(get_net_or_nullptr(cell, "I3"));
+        const NetInfo *i0 = get_net_or_empty(cell, "I0"),
+                      *i1 = get_net_or_empty(cell, "I1"),
+                      *i2 = get_net_or_empty(cell, "I2"),
+                      *i3 = get_net_or_empty(cell, "I3");
+        if (i0 != nullptr)
+            locals.insert(i0->name);
+        if (i1 != nullptr)
+            locals.insert(i1->name);
+        if (i2 != nullptr)
+            locals.insert(i2->name);
+        if (i3 != nullptr)
+            locals.insert(i3->name);
     }
 
-    locals.erase(nullptr); // disconnected signals don't use local tracks
-
     return locals.size() <= 32;
 }
 
diff --git a/ice40/bitstream.cc b/ice40/bitstream.cc
index c207f08c..4991df5e 100644
--- a/ice40/bitstream.cc
+++ b/ice40/bitstream.cc
@@ -19,6 +19,7 @@
  */
 #include "bitstream.h"
 #include <vector>
+#include "log.h"
 
 NEXTPNR_NAMESPACE_BEGIN
 
@@ -59,11 +60,16 @@ void set_config(const TileInfoPOD &ti,
     if (index == -1) {
         for (int i = 0; i < cfg.num_bits; i++) {
             int8_t &cbit = tile_cfg.at(cfg.bits[i].row).at(cfg.bits[i].col);
+            if (cbit && !value)
+                log_error("clearing already set config bit %s", name.c_str());
             cbit = value;
         }
     } else {
         int8_t &cbit = tile_cfg.at(cfg.bits[index].row).at(cfg.bits[index].col);
         cbit = value;
+        if (cbit && !value)
+            log_error("clearing already set config bit %s[%d]", name.c_str(),
+                      index);
     }
 }
 
@@ -179,7 +185,8 @@ void write_asc(const Design &design, std::ostream &out)
             for (int i = 0; i < 20; i++)
                 set_config(ti, config.at(y).at(x), "LC_" + std::to_string(z),
                            lc.at(i), i);
-            set_config(ti, config.at(y).at(x), "NegClk", neg_clk);
+            if (dff_enable)
+                set_config(ti, config.at(y).at(x), "NegClk", neg_clk);
         } else if (cell.second->type == "SB_IO") {
             const TileInfoPOD &ti = bi.tiles_nonrouting[TILE_IO];
             unsigned pin_type = get_param_or_def(cell.second, "PIN_TYPE");
diff --git a/ice40/main.cc b/ice40/main.cc
index eb92d92f..c43bffa7 100644
--- a/ice40/main.cc
+++ b/ice40/main.cc
@@ -82,6 +82,8 @@ int main(int argc, char *argv[])
                           "PCF constraints file to ingest");
     options.add_options()("asc", po::value<std::string>(),
                           "asc bitstream file to write");
+    options.add_options()("seed", po::value<int>(),
+                          "seed value for random number generator");
     options.add_options()("version,V", "show version");
     options.add_options()("lp384", "set device type to iCE40LP384");
     options.add_options()("lp1k", "set device type to iCE40LP1K");
@@ -223,8 +225,16 @@ int main(int argc, char *argv[])
 
         pack_design(&design);
         print_utilisation(&design);
+
+        int seed = 1;
+        if (vm.count("seed")) {
+            seed = vm["seed"].as<int>();
+            if (seed == 0)
+                log_error("seed must be non-zero value");
+        }
+
         if (!vm.count("pack-only")) {
-            place_design_sa(&design);
+            place_design_sa(&design, seed);
             route_design(&design, verbose);
         }
     }
diff --git a/ice40/pack.cc b/ice40/pack.cc
index 0b76f3f3..3e852a91 100644
--- a/ice40/pack.cc
+++ b/ice40/pack.cc
@@ -279,7 +279,9 @@ static void pack_io(Design *design)
 static void insert_global(Design *design, NetInfo *net, bool is_reset,
                           bool is_cen)
 {
-    CellInfo *gb = create_ice_cell(design, "SB_GB");
+    std::string glb_name = net->name.str() + std::string("_$glb_") +
+                           (is_reset ? "sr" : (is_cen ? "ce" : "clk"));
+    CellInfo *gb = create_ice_cell(design, "SB_GB", "$gbuf_" + glb_name);
     gb->ports["USER_SIGNAL_TO_GLOBAL_BUFFER"].net = net;
     PortRef pr;
     pr.cell = gb;
@@ -289,8 +291,7 @@ static void insert_global(Design *design, NetInfo *net, bool is_reset,
     pr.cell = gb;
     pr.port = "GLOBAL_BUFFER_OUTPUT";
     NetInfo *glbnet = new NetInfo();
-    glbnet->name = net->name.str() + std::string("_glb_") +
-                   (is_reset ? "sr" : (is_cen ? "ce" : "clk"));
+    glbnet->name = glb_name;
     glbnet->driver = pr;
     design->nets[glbnet->name] = glbnet;
     gb->ports["GLOBAL_BUFFER_OUTPUT"].net = glbnet;
@@ -363,19 +364,22 @@ static void promote_globals(Design *design)
             ++prom_resets;
             clock_count.erase(rstnet->name);
             reset_count.erase(rstnet->name);
-
+            cen_count.erase(rstnet->name);
         } else if (global_cen->second > global_clock->second && prom_cens < 4) {
             NetInfo *cennet = design->nets[global_cen->first];
             insert_global(design, cennet, false, true);
             ++prom_globals;
             ++prom_cens;
-            cen_count.erase(cennet->name);
             clock_count.erase(cennet->name);
+            reset_count.erase(cennet->name);
+            cen_count.erase(cennet->name);
         } else if (global_clock->second != 0) {
             NetInfo *clknet = design->nets[global_clock->first];
             insert_global(design, clknet, false, false);
             ++prom_globals;
             clock_count.erase(clknet->name);
+            reset_count.erase(clknet->name);
+            cen_count.erase(clknet->name);
         } else {
             break;
         }