diff --git a/common/nextpnr.cc b/common/nextpnr.cc
index 4e6407b2..2a581cc6 100644
--- a/common/nextpnr.cc
+++ b/common/nextpnr.cc
@@ -18,6 +18,7 @@
  */
 
 #include "nextpnr.h"
+#include "log.h"
 
 NEXTPNR_NAMESPACE_BEGIN
 
@@ -25,6 +26,7 @@ assertion_failure::assertion_failure(std::string msg, std::string expr_str, std:
         : runtime_error("Assertion failure: " + msg + " (" + filename + ":" + std::to_string(line) + ")"), msg(msg),
           expr_str(expr_str), filename(filename), line(line)
 {
+    log_flush();
 }
 
 void IdString::set(const BaseCtx *ctx, const std::string &s)
diff --git a/common/router1.cc b/common/router1.cc
index 958edf7d..ad2b6757 100644
--- a/common/router1.cc
+++ b/common/router1.cc
@@ -99,7 +99,7 @@ struct Router1
     std::priority_queue<QueuedWire, std::vector<QueuedWire>, QueuedWire::Greater> queue;
 
     std::unordered_map<WireId, int> wireScores;
-    std::unordered_map<PipId, int> pipScores;
+    std::unordered_map<NetInfo*, int> netScores;
 
     int arcs_with_ripup = 0;
     int arcs_without_ripup = 0;
@@ -124,6 +124,9 @@ struct Router1
 
     void arc_queue_insert(const arc_key &arc)
     {
+        if (queued_arcs.count(arc))
+            return;
+
         NetInfo *net_info = arc.net_info;
         int user_idx = arc.user_idx;
 
@@ -146,76 +149,79 @@ struct Router1
         if (ctx->debug)
             log("      ripup net %s\n", net->name.c_str(ctx));
 
+        netScores[net]++;
+
         auto net_wires_copy = net->wires;
         for (auto &it : net_wires_copy) {
-            if (it.second.pip == PipId())
-                ripup_wire(it.first, true);
-            else
-                ripup_pip(it.second.pip, true);
+            WireId w = it.first;
+
+            for (auto &it : wire_to_arcs[w]) {
+                arc_to_wires[it].erase(w);
+                arc_queue_insert(it);
+            }
+            wire_to_arcs[w].clear();
+
+            if (ctx->debug)
+                log("        unbind wire %s\n", ctx->getWireName(w).c_str(ctx));
+
+            ctx->unbindWire(w);
+            wireScores[w]++;
         }
 
         ripup_flag = true;
     }
 
-    void ripup_wire(WireId wire, bool extra_indent = false)
+    void ripup_wire(WireId wire, int extra_indent = 0)
     {
         if (ctx->debug)
-            log("    %sripup wire %s\n", extra_indent ? "    " : "", ctx->getWireName(wire).c_str(ctx));
+            log("    ripup wire %s\n", ctx->getWireName(wire).c_str(ctx));
 
-        wireScores[wire]++;
+        WireId w = ctx->getConflictingWireWire(wire);
 
-        if (ctx->getBoundWireNet(wire)) {
-            for (auto &it : wire_to_arcs[wire]) {
-                arc_to_wires[it].erase(wire);
+        if (w == WireId()) {
+            NetInfo *n = ctx->getConflictingWireNet(wire);
+            if (n != nullptr)
+                ripup_net(n);
+        } else {
+            for (auto &it : wire_to_arcs[w]) {
+                arc_to_wires[it].erase(w);
                 arc_queue_insert(it);
             }
-            wire_to_arcs[wire].clear();
-            ctx->unbindWire(wire);
-        }
+            wire_to_arcs[w].clear();
 
-        NetInfo *net = ctx->getConflictingWireNet(wire);
-        if (net != nullptr) {
-            wireScores[wire] += net->wires.size();
-            ripup_net(net);
+            if (ctx->debug)
+                log("      unbind wire %s\n", ctx->getWireName(w).c_str(ctx));
+
+            ctx->unbindWire(w);
+            wireScores[w]++;
         }
 
         ripup_flag = true;
     }
 
-    void ripup_pip(PipId pip, bool extra_indent = false)
+    void ripup_pip(PipId pip)
     {
-        WireId wire = ctx->getPipDstWire(pip);
-
         if (ctx->debug)
-            log("    %sripup pip %s (%s)\n", extra_indent ? "    " : "", ctx->getPipName(pip).c_str(ctx), ctx->getWireName(wire).c_str(ctx));
+            log("    ripup pip %s\n", ctx->getPipName(pip).c_str(ctx));
 
-        wireScores[wire]++;
-        pipScores[pip]++;
+        WireId w = ctx->getConflictingPipWire(pip);
 
-        if (ctx->getBoundPipNet(pip)) {
-            ctx->unbindPip(pip);
-            goto remove_wire_arcs;
-        }
-
-        if (ctx->getBoundWireNet(wire)) {
-            ctx->unbindWire(wire);
-            goto remove_wire_arcs;
-        }
-
-        if (0) {
-remove_wire_arcs:
-            for (auto &it : wire_to_arcs[wire]) {
-                arc_to_wires[it].erase(wire);
+        if (w == WireId()) {
+            NetInfo *n = ctx->getConflictingPipNet(pip);
+            if (n != nullptr)
+                ripup_net(n);
+        } else {
+            for (auto &it : wire_to_arcs[w]) {
+                arc_to_wires[it].erase(w);
                 arc_queue_insert(it);
             }
-            wire_to_arcs[wire].clear();
-        }
+            wire_to_arcs[w].clear();
 
-        NetInfo *net = ctx->getConflictingPipNet(pip);
-        if (net != nullptr) {
-            wireScores[wire] += net->wires.size();
-            pipScores[pip] += net->wires.size();
-            ripup_net(net);
+            if (ctx->debug)
+                log("      unbind wire %s\n", ctx->getWireName(w).c_str(ctx));
+
+            ctx->unbindWire(w);
+            wireScores[w]++;
         }
 
         ripup_flag = true;
@@ -247,6 +253,8 @@ remove_wire_arcs:
             if (skip_net(net_info))
                 continue;
 
+            // log("[check] net: %s\n", net_info->name.c_str(ctx));
+
             auto src_wire = ctx->getNetinfoSourceWire(net_info);
             log_assert(src_wire != WireId());
 
@@ -259,8 +267,10 @@ remove_wire_arcs:
                 arc.user_idx = user_idx;
 
                 valid_arcs.insert(arc);
+                // log("[check]   arc: %s %s\n", ctx->getWireName(src_wire).c_str(ctx), ctx->getWireName(dst_wire).c_str(ctx));
 
                 for (WireId wire : arc_to_wires[arc]) {
+                    // log("[check]     wire: %s\n", ctx->getWireName(wire).c_str(ctx));
                     valid_wires_for_net.insert(wire);
                     log_assert(wire_to_arcs[wire].count(arc));
                     log_assert(net_info->wires.count(wire));
@@ -285,6 +295,9 @@ remove_wire_arcs:
 
     void setup()
     {
+        std::unordered_map<WireId, NetInfo*> src_to_net;
+        std::unordered_map<WireId, arc_key> dst_to_arc;
+
         for (auto &net_it : ctx->nets)
         {
             NetInfo *net_info = net_it.second.get();
@@ -298,6 +311,14 @@ remove_wire_arcs:
                 log_error("No wire found for port %s on source cell %s.\n", net_info->driver.port.c_str(ctx),
                           net_info->driver.cell->name.c_str(ctx));
 
+            if (src_to_net.count(src_wire))
+                log_error("Found two nets with same source wire %s: %s vs %s\n", ctx->getWireName(src_wire).c_str(ctx),
+                          ctx->nameOf(net_info), ctx->nameOf(src_to_net.at(src_wire)));
+
+            if (dst_to_arc.count(src_wire))
+                log_error("Wire %s is used as source and sink in different nets: %s vs %s (%d)\n", ctx->getWireName(src_wire).c_str(ctx),
+                          ctx->nameOf(net_info), ctx->nameOf(dst_to_arc.at(src_wire).net_info), dst_to_arc.at(src_wire).user_idx);
+
             for (int user_idx = 0; user_idx < int(net_info->users.size()); user_idx++) {
                 auto dst_wire = ctx->getNetinfoSinkWire(net_info, net_info->users[user_idx]);
 
@@ -305,10 +326,23 @@ remove_wire_arcs:
                     log_error("No wire found for port %s on destination cell %s.\n", net_info->users[user_idx].port.c_str(ctx),
                               net_info->users[user_idx].cell->name.c_str(ctx));
 
+                if (dst_to_arc.count(dst_wire)) {
+                    if (dst_to_arc.at(dst_wire).net_info == net_info)
+                        continue;
+                    log_error("Found two arcs with same sink wire %s: %s (%d) vs %s (%d)\n", ctx->getWireName(dst_wire).c_str(ctx),
+                              ctx->nameOf(net_info), user_idx, ctx->nameOf(dst_to_arc.at(dst_wire).net_info), dst_to_arc.at(dst_wire).user_idx);
+                }
+
+                if (src_to_net.count(dst_wire))
+                    log_error("Wire %s is used as source and sink in different nets: %s vs %s (%d)\n", ctx->getWireName(dst_wire).c_str(ctx),
+                              ctx->nameOf(src_to_net.at(dst_wire)), ctx->nameOf(net_info), user_idx);
+
                 arc_key arc;
                 arc.net_info = net_info;
                 arc.user_idx = user_idx;
 
+                dst_to_arc[dst_wire] = arc;
+
                 if (net_info->wires.count(src_wire) == 0) {
                     arc_queue_insert(arc, src_wire, dst_wire);
                     continue;
@@ -332,6 +366,8 @@ remove_wire_arcs:
                 }
             }
 
+            src_to_net[src_wire] = net_info;
+
             std::vector<WireId> unbind_wires;
 
             for (auto &it : net_info->wires)
@@ -420,43 +456,74 @@ remove_wire_arcs:
                 WireId next_wire = ctx->getPipDstWire(pip);
                 next_delay += ctx->getWireDelay(next_wire).maxDelay();
 
-                if (!ctx->checkWireAvail(next_wire)) {
-                    NetInfo *ripupWireNet = ctx->getConflictingWireNet(next_wire);
+                WireId conflictWireWire = WireId(), conflictPipWire = WireId();
+                NetInfo *conflictWireNet = nullptr, *conflictPipNet = nullptr;
 
-                    if (ripupWireNet == nullptr)
-                        continue;
-
-                    if (ripupWireNet == net_info) {
-                        next_bonus += cfg.wireReuseBonus;
-                    } else {
+                if (net_info->wires.count(next_wire) && net_info->wires.at(next_wire).pip == pip) {
+                    next_bonus += cfg.reuseBonus;
+                } else {
+                    if (!ctx->checkWireAvail(next_wire)) {
                         if (!ripup)
                             continue;
+                        conflictWireWire = ctx->getConflictingWireWire(next_wire);
+                        if (conflictWireWire == WireId()) {
+                            conflictWireNet = ctx->getConflictingWireNet(next_wire);
+                            if (conflictWireNet == nullptr)
+                                continue;
+                        }
+                    }
 
-                        auto scores_it = wireScores.find(next_wire);
+                    if (!ctx->checkPipAvail(pip)) {
+                        if (!ripup)
+                            continue;
+                        conflictPipWire = ctx->getConflictingPipWire(pip);
+                        if (conflictPipWire == WireId()) {
+                            conflictPipNet = ctx->getConflictingPipNet(pip);
+                            if (conflictPipNet == nullptr)
+                                continue;
+                        }
+                    }
+
+                    if (conflictWireNet != nullptr && conflictPipWire != WireId() && conflictWireNet->wires.count(conflictPipWire))
+                        conflictPipWire = WireId();
+
+                    if (conflictPipNet != nullptr && conflictWireWire != WireId() && conflictPipNet->wires.count(conflictWireWire))
+                        conflictWireWire = WireId();
+
+                    if (conflictWireWire == conflictPipWire)
+                        conflictWireWire = WireId();
+
+                    if (conflictWireNet == conflictPipNet)
+                        conflictWireNet = nullptr;
+
+                    if (conflictWireWire != WireId()) {
+                        auto scores_it = wireScores.find(conflictWireWire);
                         if (scores_it != wireScores.end())
                             next_penalty += scores_it->second * cfg.wireRipupPenalty;
-                        else
-                            next_penalty += cfg.wireRipupPenalty;
+                        next_penalty += cfg.wireRipupPenalty;
                     }
-                }
 
-                if (!ctx->checkPipAvail(pip)) {
-                    NetInfo *ripupPipNet = ctx->getConflictingPipNet(pip);
+                    if (conflictPipWire != WireId()) {
+                        auto scores_it = wireScores.find(conflictPipWire);
+                        if (scores_it != wireScores.end())
+                            next_penalty += scores_it->second * cfg.wireRipupPenalty;
+                        next_penalty += cfg.wireRipupPenalty;
+                    }
 
-                    if (ripupPipNet == nullptr)
-                        continue;
+                    if (conflictWireNet != nullptr) {
+                        auto scores_it = netScores.find(conflictWireNet);
+                        if (scores_it != netScores.end())
+                            next_penalty += scores_it->second * cfg.netRipupPenalty;
+                        next_penalty += cfg.netRipupPenalty;
+                        next_penalty += conflictWireNet->wires.size() * cfg.wireRipupPenalty;
+                    }
 
-                    if (ripupPipNet == net_info) {
-                        next_bonus += cfg.pipReuseBonus;
-                    } else {
-                        if (!ripup)
-                            continue;
-
-                        auto scores_it = pipScores.find(pip);
-                        if (scores_it != pipScores.end())
-                            next_penalty += scores_it->second * cfg.pipRipupPenalty;
-                        else
-                            next_penalty += cfg.pipRipupPenalty;
+                    if (conflictPipNet != nullptr) {
+                        auto scores_it = netScores.find(conflictPipNet);
+                        if (scores_it != netScores.end())
+                            next_penalty += scores_it->second * cfg.netRipupPenalty;
+                        next_penalty += cfg.netRipupPenalty;
+                        next_penalty += conflictPipNet->wires.size() * cfg.wireRipupPenalty;
                     }
                 }
 
@@ -475,9 +542,6 @@ remove_wire_arcs:
                     if (next_score + ctx->getDelayEpsilon() >= old_score)
                         continue;
 
-                    if (next_delay + ctx->getDelayEpsilon() >= old_delay)
-                        continue;
-
 #if 0
                     if (ctx->debug)
                         log("Found better route to %s. Old vs new delay estimate: %.3f (%.3f) %.3f (%.3f)\n",
@@ -534,47 +598,44 @@ remove_wire_arcs:
             return false;
         }
 
+        if (ctx->debug) {
+            log("  final route delay:   %8.2f\n", ctx->getDelayNS(visited[dst_wire].delay));
+            log("  final route penalty: %8.2f\n", ctx->getDelayNS(visited[dst_wire].penalty));
+            log("  final route bonus:   %8.2f\n", ctx->getDelayNS(visited[dst_wire].bonus));
+        }
+
         // bind resulting route (and maybe unroute other nets)
 
         std::unordered_set<WireId> unassign_wires = arc_to_wires[arc];
 
         WireId cursor = dst_wire;
         while (1) {
+            auto pip = visited[cursor].pip;
+
             if (ctx->debug)
                 log("  node %s\n", ctx->getWireName(cursor).c_str(ctx));
 
-            if (!ctx->checkWireAvail(cursor)) {
-                NetInfo *ripupWireNet = ctx->getConflictingWireNet(cursor);
-                NPNR_ASSERT(ripupWireNet != nullptr);
+                if (pip == PipId())
+                    NPNR_ASSERT(cursor == src_wire);
 
-                if (ripupWireNet != net_info) {
+            if (!net_info->wires.count(cursor) || net_info->wires.at(cursor).pip != pip) {
+                if (!ctx->checkWireAvail(cursor)) {
                     ripup_wire(cursor);
                     NPNR_ASSERT(ctx->checkWireAvail(cursor));
                 }
-            }
 
-            auto pip = visited[cursor].pip;
-
-            if (pip == PipId()) {
-                NPNR_ASSERT(cursor == src_wire);
-            } else {
-                if (!ctx->checkPipAvail(pip)) {
-                    NetInfo *ripupPipNet = ctx->getConflictingPipNet(pip);
-                    NPNR_ASSERT(ripupPipNet != nullptr);
-
-                    if (ripupPipNet != net_info || net_info->wires.at(cursor).pip != pip)
-                        ripup_pip(pip);
+                if (pip != PipId() && !ctx->checkPipAvail(pip)) {
+                    ripup_pip(pip);
+                    NPNR_ASSERT(ctx->checkPipAvail(pip));
                 }
-            }
 
-            if (ctx->checkWireAvail(cursor)) {
                 if (pip == PipId()) {
                     if (ctx->debug)
-                        log("    bind %s\n", ctx->getWireName(cursor).c_str(ctx));
+                        log("    bind wire %s\n", ctx->getWireName(cursor).c_str(ctx));
                     ctx->bindWire(cursor, net_info, STRENGTH_WEAK);
-                } else if (ctx->checkPipAvail(pip)) {
+                } else {
                     if (ctx->debug)
-                        log("    bind %s\n", ctx->getPipName(pip).c_str(ctx));
+                        log("    bind pip %s\n", ctx->getPipName(pip).c_str(ctx));
                     ctx->bindPip(pip, net_info, STRENGTH_WEAK);
                 }
             }
@@ -609,10 +670,8 @@ Router1Cfg::Router1Cfg(Context *ctx) : Settings(ctx)
     useEstimate = get<bool>("router1/useEstimate", true);
 
     wireRipupPenalty = ctx->getRipupDelayPenalty();
-    pipRipupPenalty = ctx->getRipupDelayPenalty();
-
-    wireReuseBonus = wireRipupPenalty/8;
-    pipReuseBonus = pipRipupPenalty/8;
+    netRipupPenalty = 10*ctx->getRipupDelayPenalty();
+    reuseBonus = wireRipupPenalty/2;
 
     estimatePrecision = 100 * ctx->getRipupDelayPenalty();
 }
@@ -649,15 +708,21 @@ bool router1(Context *ctx, const Router1Cfg &cfg)
                         router.arcs_without_ripup - last_arcs_without_ripup, int(router.arc_queue.size()));
                 last_arcs_with_ripup = router.arcs_with_ripup;
                 last_arcs_without_ripup = router.arcs_without_ripup;
+#ifndef NDEBUG
                 router.check();
+#endif
             }
 
+            if (ctx->debug)
+                log("-- %d --\n", iter_cnt);
+
             arc_key arc = router.arc_queue_pop();
 
             if (!router.route_arc(arc, true)) {
                 log_warning("Failed to find a route for arc %d of net %s.\n",
                         arc.user_idx, arc.net_info->name.c_str(ctx));
 #ifndef NDEBUG
+                router.check();
                 ctx->check();
 #endif
                 ctx->unlock();
@@ -669,18 +734,17 @@ bool router1(Context *ctx, const Router1Cfg &cfg)
                 iter_cnt, router.arcs_with_ripup, router.arcs_without_ripup,
                 router.arcs_with_ripup - last_arcs_with_ripup,
                 router.arcs_without_ripup - last_arcs_without_ripup, int(router.arc_queue.size()));
+        log_info("Routing complete.\n");
+
 #ifndef NDEBUG
         router.check();
+        ctx->check();
+        log_assert(ctx->checkRoutedDesign());
 #endif
 
-        log_info("Routing complete.\n");
-        ctx->checkRoutedDesign();
-
         log_info("Checksum: 0x%08x\n", ctx->checksum());
-#ifndef NDEBUG
-        ctx->check();
-#endif
         timing_analysis(ctx, true /* slack_histogram */, true /* print_path */);
+
         ctx->unlock();
         return true;
     } catch (log_execution_error_exception) {
@@ -772,9 +836,11 @@ bool Context::checkRoutedDesign() const
                 }
                 if (db_entry.children.empty()) {
                     if (dest_wires.count(w) != 0) {
-                        log("  %*s=> sink %d\n", 2*num, "", dest_wires.at(w));
+                        if (ctx->debug)
+                            log("  %*s=> sink %d\n", 2*num, "", dest_wires.at(w));
                     } else {
-                        log("  %*s=> stub\n", 2*num, "");
+                        if (ctx->debug)
+                            log("  %*s=> stub\n", 2*num, "");
                         found_stub = true;
                     }
                 }
@@ -820,10 +886,34 @@ bool Context::checkRoutedDesign() const
                 }
             }
 
-            log_assert(!found_unrouted);
-            log_assert(!found_loop);
-            log_assert(!found_stub);
-            log_assert(dangling_wires.empty());
+            bool fail = false;
+
+            if (found_unrouted) {
+                if (ctx->debug)
+                    log("check failed: found unrouted arcs\n");
+                fail = true;
+            }
+
+            if (found_loop) {
+                if (ctx->debug)
+                    log("check failed: found loops\n");
+                fail = true;
+            }
+
+            if (found_stub) {
+                if (ctx->debug)
+                    log("check failed: found stubs\n");
+                fail = true;
+            }
+
+            if (!dangling_wires.empty()) {
+                if (ctx->debug)
+                    log("check failed: found dangling wires\n");
+                fail = true;
+            }
+
+            if (fail)
+                return false;
         }
 
         return true;
diff --git a/common/router1.h b/common/router1.h
index 120bf30e..80d7aa96 100644
--- a/common/router1.h
+++ b/common/router1.h
@@ -34,9 +34,8 @@ struct Router1Cfg : Settings
     bool fullCleanupReroute;
     bool useEstimate;
     delay_t wireRipupPenalty;
-    delay_t pipRipupPenalty;
-    delay_t wireReuseBonus;
-    delay_t pipReuseBonus;
+    delay_t netRipupPenalty;
+    delay_t reuseBonus;
     delay_t estimatePrecision;
 };
 
diff --git a/docs/archapi.md b/docs/archapi.md
index 73443c15..85bc6ccd 100644
--- a/docs/archapi.md
+++ b/docs/archapi.md
@@ -215,14 +215,15 @@ Return true if the wire is available, i.e. can be bound to a net.
 
 Return the net a wire is bound to.
 
-### NetInfo \*getConflictingWireNet(WireId wire) const
+### WireId getConflictingWireWire(WireId wire) const
 
-If this returns a non-nullptr, then unbinding that net
+If this returns a non-WireId(), then unbinding that wire
 will make the given wire available.
 
-This returns nullptr if the wire is already available,
-or if there is no single net that can be unbound to make this
-wire available.
+### NetInfo \*getConflictingWireNet(WireId wire) const
+
+If this returns a non-nullptr, then unbinding that entire net
+will make the given wire available.
 
 ### DelayInfo getWireDelay(WireId wire) const
 
@@ -282,18 +283,23 @@ This method must also update `NetInfo::wires`.
 
 Returns true if the given pip is available to be bound to a net.
 
+Users must also check if the pip destination wire is available
+with `checkWireAvail(getPipDstWire(pip))` before binding the
+pip to a net.
+
 ### NetInfo \*getBoundPipNet(PipId pip) const
 
 Return the net this pip is bound to.
 
+### WireId getConflictingPipWire(PipId pip) const
+
+If this returns a non-WireId(), then unbinding that wire
+will make the given pip available.
+
 ### NetInfo \*getConflictingPipNet(PipId pip) const
 
-Return the net that needs to be unbound in order to make this
-pip available.
-
-This does not need to (but may) return the conflicting wire if the conflict is
-limited to the conflicting wire being bound to the destination wire for this
-pip.
+If this returns a non-nullptr, then unbinding that entire net
+will make the given pip available.
 
 ### const\_range\<PipId\> getPips() const
 
diff --git a/ecp5/arch.h b/ecp5/arch.h
index 583d539f..bd4881c2 100644
--- a/ecp5/arch.h
+++ b/ecp5/arch.h
@@ -619,6 +619,11 @@ struct Arch : BaseCtx
             return wire_to_net.at(wire);
     }
 
+    WireId getConflictingWireWire(WireId wire) const
+    {
+        return wire;
+    }
+
     NetInfo *getConflictingWireNet(WireId wire) const
     {
         NPNR_ASSERT(wire != WireId());
@@ -724,6 +729,11 @@ struct Arch : BaseCtx
             return pip_to_net.at(pip);
     }
 
+    WireId getConflictingPipWire(PipId pip) const
+    {
+        return WireId();
+    }
+
     NetInfo *getConflictingPipNet(PipId pip) const
     {
         NPNR_ASSERT(pip != PipId());
diff --git a/generic/arch.cc b/generic/arch.cc
index 3e95159a..4f2e07a2 100644
--- a/generic/arch.cc
+++ b/generic/arch.cc
@@ -373,6 +373,8 @@ NetInfo *Arch::getBoundPipNet(PipId pip) const { return pips.at(pip).bound_net;
 
 NetInfo *Arch::getConflictingPipNet(PipId pip) const { return pips.at(pip).bound_net; }
 
+WireId Arch::getConflictingPipWire(PipId pip) const { return pips.at(pip).bound_net ? pips.at(pip).dstWire : WireId(); }
+
 const std::vector<PipId> &Arch::getPips() const { return pip_ids; }
 
 Loc Arch::getPipLocation(PipId pip) const { return pips.at(pip).loc; }
diff --git a/generic/arch.h b/generic/arch.h
index 22966e2a..9311464e 100644
--- a/generic/arch.h
+++ b/generic/arch.h
@@ -172,6 +172,7 @@ struct Arch : BaseCtx
     void unbindWire(WireId wire);
     bool checkWireAvail(WireId wire) const;
     NetInfo *getBoundWireNet(WireId wire) const;
+    WireId getConflictingWireWire(WireId wire) const { return wire; }
     NetInfo *getConflictingWireNet(WireId wire) const;
     DelayInfo getWireDelay(WireId wire) const { return DelayInfo(); }
     const std::vector<WireId> &getWires() const;
@@ -186,6 +187,7 @@ struct Arch : BaseCtx
     void unbindPip(PipId pip);
     bool checkPipAvail(PipId pip) const;
     NetInfo *getBoundPipNet(PipId pip) const;
+    WireId getConflictingPipWire(PipId pip) const;
     NetInfo *getConflictingPipNet(PipId pip) const;
     const std::vector<PipId> &getPips() const;
     Loc getPipLocation(PipId pip) const;
diff --git a/gui/designwidget.cc b/gui/designwidget.cc
index a45752fc..8a134c1f 100644
--- a/gui/designwidget.cc
+++ b/gui/designwidget.cc
@@ -453,6 +453,8 @@ void DesignWidget::onSelectionChanged(const QItemSelection &, const QItemSelecti
         addProperty(topItem, QVariant::String, "Type", ctx->getWireType(wire).c_str(ctx));
         addProperty(topItem, QVariant::Bool, "Available", ctx->checkWireAvail(wire));
         addProperty(topItem, QVariant::String, "Bound Net", ctx->nameOf(ctx->getBoundWireNet(wire)), ElementType::NET);
+        addProperty(topItem, QVariant::String, "Conflicting Wire", ctx->getWireName(ctx->getConflictingWireWire(wire)).c_str(ctx),
+                    ElementType::WIRE);
         addProperty(topItem, QVariant::String, "Conflicting Net", ctx->nameOf(ctx->getConflictingWireNet(wire)),
                     ElementType::NET);
 
@@ -513,6 +515,8 @@ void DesignWidget::onSelectionChanged(const QItemSelection &, const QItemSelecti
         addProperty(topItem, QVariant::String, "Type", ctx->getPipType(pip).c_str(ctx));
         addProperty(topItem, QVariant::Bool, "Available", ctx->checkPipAvail(pip));
         addProperty(topItem, QVariant::String, "Bound Net", ctx->nameOf(ctx->getBoundPipNet(pip)), ElementType::NET);
+        addProperty(topItem, QVariant::String, "Conflicting Wire", ctx->getWireName(ctx->getConflictingPipWire(pip)).c_str(ctx),
+                    ElementType::WIRE);
         addProperty(topItem, QVariant::String, "Conflicting Net", ctx->nameOf(ctx->getConflictingPipNet(pip)),
                     ElementType::NET);
         addProperty(topItem, QVariant::String, "Src Wire", ctx->getWireName(ctx->getPipSrcWire(pip)).c_str(ctx),
diff --git a/ice40/arch.h b/ice40/arch.h
index 27d5db9f..2967ee1f 100644
--- a/ice40/arch.h
+++ b/ice40/arch.h
@@ -404,7 +404,7 @@ struct Arch : BaseCtx
     std::vector<CellInfo *> bel_to_cell;
     std::vector<NetInfo *> wire_to_net;
     std::vector<NetInfo *> pip_to_net;
-    std::vector<NetInfo *> switches_locked;
+    std::vector<WireId> switches_locked;
 
     ArchArgs args;
     Arch(ArchArgs args);
@@ -546,7 +546,7 @@ struct Arch : BaseCtx
         auto pip = it->second.pip;
         if (pip != PipId()) {
             pip_to_net[pip.index] = nullptr;
-            switches_locked[chip_info->pip_data[pip.index].switch_index] = nullptr;
+            switches_locked[chip_info->pip_data[pip.index].switch_index] = WireId();
         }
 
         net_wires.erase(it);
@@ -566,6 +566,11 @@ struct Arch : BaseCtx
         return wire_to_net[wire.index];
     }
 
+    WireId getConflictingWireWire(WireId wire) const
+    {
+        return wire;
+    }
+
     NetInfo *getConflictingWireNet(WireId wire) const
     {
         NPNR_ASSERT(wire != WireId());
@@ -608,14 +613,15 @@ struct Arch : BaseCtx
     {
         NPNR_ASSERT(pip != PipId());
         NPNR_ASSERT(pip_to_net[pip.index] == nullptr);
-        NPNR_ASSERT(switches_locked[chip_info->pip_data[pip.index].switch_index] == nullptr);
-
-        pip_to_net[pip.index] = net;
-        switches_locked[chip_info->pip_data[pip.index].switch_index] = net;
+        NPNR_ASSERT(switches_locked[chip_info->pip_data[pip.index].switch_index] == WireId());
 
         WireId dst;
         dst.index = chip_info->pip_data[pip.index].dst;
         NPNR_ASSERT(wire_to_net[dst.index] == nullptr);
+
+        pip_to_net[pip.index] = net;
+        switches_locked[chip_info->pip_data[pip.index].switch_index] = dst;
+
         wire_to_net[dst.index] = net;
         net->wires[dst].pip = pip;
         net->wires[dst].strength = strength;
@@ -627,7 +633,7 @@ struct Arch : BaseCtx
     {
         NPNR_ASSERT(pip != PipId());
         NPNR_ASSERT(pip_to_net[pip.index] != nullptr);
-        NPNR_ASSERT(switches_locked[chip_info->pip_data[pip.index].switch_index] != nullptr);
+        NPNR_ASSERT(switches_locked[chip_info->pip_data[pip.index].switch_index] != WireId());
 
         WireId dst;
         dst.index = chip_info->pip_data[pip.index].dst;
@@ -636,33 +642,39 @@ struct Arch : BaseCtx
         pip_to_net[pip.index]->wires.erase(dst);
 
         pip_to_net[pip.index] = nullptr;
-        switches_locked[chip_info->pip_data[pip.index].switch_index] = nullptr;
+        switches_locked[chip_info->pip_data[pip.index].switch_index] = WireId();
         refreshUiPip(pip);
         refreshUiWire(dst);
     }
 
-    bool checkPipAvail(PipId pip) const
+    bool ice40_pip_hard_unavail(PipId pip) const
     {
         NPNR_ASSERT(pip != PipId());
         auto &pi = chip_info->pip_data[pip.index];
         auto &si = chip_info->bits_info->switches[pi.switch_index];
 
-        if (switches_locked[pi.switch_index] != nullptr)
-            return false;
-
         if (pi.flags & PipInfoPOD::FLAG_ROUTETHRU) {
             NPNR_ASSERT(si.bel >= 0);
             if (bel_to_cell[si.bel] != nullptr)
-                return false;
+                return true;
         }
 
         if (pi.flags & PipInfoPOD::FLAG_NOCARRY) {
             NPNR_ASSERT(si.bel >= 0);
             if (bel_carry[si.bel])
-                return false;
+                return true;
         }
 
-        return true;
+        return false;
+    }
+
+    bool checkPipAvail(PipId pip) const
+    {
+        if (ice40_pip_hard_unavail(pip))
+            return false;
+
+        auto &pi = chip_info->pip_data[pip.index];
+        return switches_locked[pi.switch_index] == WireId();
     }
 
     NetInfo *getBoundPipNet(PipId pip) const
@@ -671,10 +683,21 @@ struct Arch : BaseCtx
         return pip_to_net[pip.index];
     }
 
+    WireId getConflictingPipWire(PipId pip) const
+    {
+        if (ice40_pip_hard_unavail(pip))
+            return WireId();
+
+        return switches_locked[chip_info->pip_data[pip.index].switch_index];
+    }
+
     NetInfo *getConflictingPipNet(PipId pip) const
     {
-        NPNR_ASSERT(pip != PipId());
-        return switches_locked[chip_info->pip_data[pip.index].switch_index];
+        if (ice40_pip_hard_unavail(pip))
+            return nullptr;
+
+        WireId wire = switches_locked[chip_info->pip_data[pip.index].switch_index];
+        return wire == WireId() ? nullptr : wire_to_net[wire.index];
     }
 
     AllPipRange getPips() const