Merge remote-tracking branch 'origin/master' into timingapi

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)
@@ -152,6 +154,30 @@ void BaseCtx::removeConstraint(IdString constrName)
     constraints.erase(constrName);
 }
 
+const char *BaseCtx::nameOfBel(BelId bel) const
+{
+    const Context *ctx = getCtx();
+    return ctx->getBelName(bel).c_str(ctx);
+}
+
+const char *BaseCtx::nameOfWire(WireId wire) const
+{
+    const Context *ctx = getCtx();
+    return ctx->getWireName(wire).c_str(ctx);
+}
+
+const char *BaseCtx::nameOfPip(PipId pip) const
+{
+    const Context *ctx = getCtx();
+    return ctx->getPipName(pip).c_str(ctx);
+}
+
+const char *BaseCtx::nameOfGroup(GroupId group) const
+{
+    const Context *ctx = getCtx();
+    return ctx->getGroupName(group).c_str(ctx);
+}
+
 WireId Context::getNetinfoSourceWire(const NetInfo *net_info) const
 {
     if (net_info->driver.cell == nullptr)

common/nextpnr.h

@@ -288,7 +288,7 @@ struct ClockConstraint;
 struct NetInfo : ArchNetInfo
 {
     IdString name;
-    int32_t udata;
+    int32_t udata = 0;
 
     PortRef driver;
     std::vector<PortRef> users;
@@ -579,13 +579,23 @@ struct BaseCtx
 
     const Context *getCtx() const { return reinterpret_cast<const Context *>(this); }
 
-    template <typename T> const char *nameOf(const T *obj)
+    const char *nameOf(IdString name) const
+    {
+        return name.c_str(this);
+    }
+
+    template <typename T> const char *nameOf(const T *obj) const
     {
         if (obj == nullptr)
             return "";
-        return obj->name.c_str(getCtx());
+        return obj->name.c_str(this);
     }
 
+    const char *nameOfBel(BelId bel) const;
+    const char *nameOfWire(WireId wire) const;
+    const char *nameOfPip(PipId pip) const;
+    const char *nameOfGroup(GroupId group) const;
+
     // --------------------------------------------------------------
 
     bool allUiReload = true;
@@ -657,6 +667,7 @@ struct Context : Arch, DeterministicRNG
     delay_t getNetinfoRouteDelay(const NetInfo *net_info, const PortRef &sink) const;
 
     // provided by router1.cc
+    bool checkRoutedDesign() const;
     bool getActualRouteDelay(WireId src_wire, WireId dst_wire, delay_t *delay = nullptr,
                              std::unordered_map<WireId, PipId> *route = nullptr, bool useEstimate = true);
 

common/place_common.cc

@@ -28,19 +28,19 @@ NEXTPNR_NAMESPACE_BEGIN
 wirelen_t get_net_metric(const Context *ctx, const NetInfo *net, MetricType type, float &tns)
 {
     wirelen_t wirelength = 0;
-    Loc driver_loc;
-    bool driver_gb;
     CellInfo *driver_cell = net->driver.cell;
     if (!driver_cell)
         return 0;
     if (driver_cell->bel == BelId())
         return 0;
-    driver_gb = ctx->getBelGlobalBuf(driver_cell->bel);
+    bool driver_gb = ctx->getBelGlobalBuf(driver_cell->bel);
-    driver_loc = ctx->getBelLocation(driver_cell->bel);
     if (driver_gb)
         return 0;
+    IdString clock_port;
+    bool timing_driven = ctx->timing_driven && type == MetricType::COST && ctx->getPortTimingClass(driver_cell, net->driver.port, clock_port) != TMG_IGNORE;
     delay_t negative_slack = 0;
     delay_t worst_slack = std::numeric_limits<delay_t>::max();
+    Loc driver_loc = ctx->getBelLocation(driver_cell->bel);
     int xmin = driver_loc.x, xmax = driver_loc.x, ymin = driver_loc.y, ymax = driver_loc.y;
     for (auto load : net->users) {
         if (load.cell == nullptr)
@@ -48,7 +48,7 @@ wirelen_t get_net_metric(const Context *ctx, const NetInfo *net, MetricType type
         CellInfo *load_cell = load.cell;
         if (load_cell->bel == BelId())
             continue;
-        if (ctx->timing_driven && type == MetricType::COST) {
+        if (timing_driven) {
             delay_t net_delay = ctx->predictDelay(net, load);
             auto slack = load.budget - net_delay;
             if (slack < 0)
@@ -65,7 +65,7 @@ wirelen_t get_net_metric(const Context *ctx, const NetInfo *net, MetricType type
         xmax = std::max(xmax, load_loc.x);
         ymax = std::max(ymax, load_loc.y);
     }
-    if (ctx->timing_driven && type == MetricType::COST) {
+    if (timing_driven) {
         wirelength = wirelen_t(
                 (((ymax - ymin) + (xmax - xmin)) * std::min(5.0, (1.0 + std::exp(-ctx->getDelayNS(worst_slack) / 5)))));
     } else {

common/router1.h

@@ -33,6 +33,10 @@ struct Router1Cfg : Settings
     bool cleanupReroute;
     bool fullCleanupReroute;
     bool useEstimate;
+    delay_t wireRipupPenalty;
+    delay_t netRipupPenalty;
+    delay_t reuseBonus;
+    delay_t estimatePrecision;
 };
 
 extern bool router1(Context *ctx, const Router1Cfg &cfg);

docs/archapi.md

@@ -30,15 +30,15 @@ delay_t maxDelay() const { return delay; }
 
 ### BelId
 
-A type representing a bel name. `BelId()` must construct a unique null-value. Must provide `==` and `!=` operators and a specialization for `std::hash<BelId>`.
+A type representing a bel name. `BelId()` must construct a unique null-value. Must provide `==`, `!=`, and `<` operators and a specialization for `std::hash<BelId>`.
 
 ### WireId
 
-A type representing a wire name. `WireId()` must construct a unique null-value. Must provide `==` and `!=` operators and a specialization for `std::hash<WireId>`.
+A type representing a wire name. `WireId()` must construct a unique null-value. Must provide `==`, `!=`, and `<` operators and a specialization for `std::hash<WireId>`.
 
 ### PipId
 
-A type representing a pip name. `PipId()` must construct a unique null-value. Must provide `==` and `!=` operators and a specialization for `std::hash<PipId>`.
+A type representing a pip name. `PipId()` must construct a unique null-value. Must provide `==`, `!=`, and `<` operators and a specialization for `std::hash<PipId>`.
 
 ### GroupId
 
@@ -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,
+### NetInfo \*getConflictingWireNet(WireId wire) const
-or if there is no single net that can be unbound to make this
+
-wire available.
+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
+If this returns a non-nullptr, then unbinding that entire net
-pip available.
+will make the given 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.
 
 ### const\_range\<PipId\> getPips() const
 

docs/faq.md

@@ -38,7 +38,94 @@ For nextpnr we are using the following terminology.
 Adding new architectures to nextpnr
 -----------------------------------
 
-TBD
+### Implementing new architectures
+
+Each nextpnr architecture must implement the *nextpnr architecture API*.
+See [archapi.md](archapi.md) for a complete reference of the architecture API.
+
+### Delay Estimates
+
+Each architecture must implement a `estimateDelay()` method that estimates the expected delay for a path from given `src` to `dst` wires.
+*It is very important that this method slightly overestimates the expected delay.* Furthermore, it should overestimate the expected delay
+by a slightly larger margin for longer paths than for shorter paths. Otherwise there will be performance issues with the router.
+
+The delays estimates returned by that method should also be as fine-grain as possible. It definitely pays off to spend some time improving the `estimateDelay()`
+for your architecture once implementing small designs work.
+
+### Ripup Information
+
+The `getConflictingWireWire()`, `getConflictingWireNet()`, `getConflictingPipWire()`, and `getConflictingPipNet()` methods are used by the router
+to determine which resources to rip up in order to make a given routing resource (wire or pip) available.
+
+The architecture must guanrantee that the following invariants hold.
+
+**Invariant 1:**
+
+```
+    if (!ctx->checkWireAvail(wire)) {
+        WireId w = getConflictingWireWire(wire);
+        if (w != WireId()) {
+            ctx->unbindWire(w);
+            assert(ctx->checkWireAvail(wire));
+        }
+    }
+```
+
+**Invariant 2:**
+
+```
+    if (!ctx->checkWireAvail(wire)) {
+        NetInfo *n = getConflictingWireNet(wire);
+        if (n != nullptr) {
+            for (auto &it : n->wires)
+                ctx->unbindWire(it.first);
+            assert(ctx->checkWireAvail(wire));
+        }
+    }
+```
+
+**Invariant 3:**
+
+```
+    if (!ctx->checkPipAvail(pip)) {
+        WireId w = getConflictingPipWire(pip);
+        if (w != WireId()) {
+            ctx->unbindWire(w);
+            assert(ctx->checkPipAvail(pip));
+        }
+    }
+```
+
+**Invariant 4:**
+
+```
+    if (!ctx->checkPipAvail(pip)) {
+        NetInfo *n = getConflictingPipNet(pip);
+        if (n != nullptr) {
+            for (auto &it : n->wires)
+                ctx->unbindWire(it.first);
+            assert(ctx->checkPipAvail(pip));
+        }
+    }
+```
+
+**Invariant 5:**
+
+```
+    if (ctx->checkWireAvail(wire)) {
+        // bind is guaranteed to succeed
+        ctx->bindWire(wire, net, strength);
+    }
+```
+
+**Invariant 6:**
+
+```
+    if (ctx->checkPipAvail(pip) && ctx->checkWireAvail(ctx->getPipDstWire(pip))) {
+        // bind is guaranteed to succeed
+        ctx->bindPip(pip, net, strength);
+    }
+```
 
 Nextpnr and other tools
 -----------------------

ecp5/arch.cc

@@ -400,7 +400,7 @@ BelId Arch::getBelByLocation(Loc loc) const
 
 delay_t Arch::estimateDelay(WireId src, WireId dst) const
 {
-    return 100 * (abs(src.location.x - dst.location.x) + abs(src.location.y - dst.location.y));
+    return 170 * (abs(src.location.x - dst.location.x) + abs(src.location.y - dst.location.y));
 }
 
 delay_t Arch::predictDelay(const NetInfo *net_info, const PortRef &sink) const
@@ -409,7 +409,7 @@ delay_t Arch::predictDelay(const NetInfo *net_info, const PortRef &sink) const
     auto driver_loc = getBelLocation(driver.cell->bel);
     auto sink_loc = getBelLocation(sink.cell->bel);
 
-    return 100 * (abs(driver_loc.x - sink_loc.x) + abs(driver_loc.y - sink_loc.y));
+    return 170 * (abs(driver_loc.x - sink_loc.x) + abs(driver_loc.y - sink_loc.y));
 }
 
 bool Arch::getBudgetOverride(const NetInfo *net_info, const PortRef &sink, delay_t &budget) const { return false; }

ecp5/arch.h

@@ -619,6 +619,8 @@ 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 +726,8 @@ 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());

ecp5/archdefs.h

@@ -75,6 +75,7 @@ struct Location
 
     bool operator==(const Location &other) const { return x == other.x && y == other.y; }
     bool operator!=(const Location &other) const { return x != other.x || y != other.y; }
+    bool operator<(const Location &other) const { return y == other.y ? x < other.x : y < other.y; }
 };
 
 inline Location operator+(const Location &a, const Location &b) { return Location(a.x + b.x, a.y + b.y); }
@@ -86,6 +87,7 @@ struct BelId
 
     bool operator==(const BelId &other) const { return index == other.index && location == other.location; }
     bool operator!=(const BelId &other) const { return index != other.index || location != other.location; }
+    bool operator<(const BelId &other) const { return location == other.location ? index < other.index : location < other.location; }
 };
 
 struct WireId
@@ -95,6 +97,7 @@ struct WireId
 
     bool operator==(const WireId &other) const { return index == other.index && location == other.location; }
     bool operator!=(const WireId &other) const { return index != other.index || location != other.location; }
+    bool operator<(const WireId &other) const { return location == other.location ? index < other.index : location < other.location; }
 };
 
 struct PipId
@@ -104,6 +107,7 @@ struct PipId
 
     bool operator==(const PipId &other) const { return index == other.index && location == other.location; }
     bool operator!=(const PipId &other) const { return index != other.index || location != other.location; }
+    bool operator<(const PipId &other) const { return location == other.location ? index < other.index : location < other.location; }
 };
 
 struct GroupId

ecp5/main.cc

@@ -40,7 +40,7 @@ class ECP5CommandHandler : public CommandHandler
     void customBitstream(Context *ctx) override;
 
   protected:
-    po::options_description getArchOptions();
+    po::options_description getArchOptions() override;
 };
 
 ECP5CommandHandler::ECP5CommandHandler(int argc, char **argv) : CommandHandler(argc, argv) {}

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; }

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;

generic/main.cc

@@ -37,7 +37,7 @@ class GenericCommandHandler : public CommandHandler
     void customBitstream(Context *ctx) override;
 
   protected:
-    po::options_description getArchOptions();
+    po::options_description getArchOptions() override;
 };
 
 GenericCommandHandler::GenericCommandHandler(int argc, char **argv) : CommandHandler(argc, argv) {}

gui/designwidget.cc

@@ -638,6 +638,8 @@ void DesignWidget::onSelectionChanged(int num, const QItemSelection &, const QIt
         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);
 
@@ -698,6 +700,8 @@ void DesignWidget::onSelectionChanged(int num, const QItemSelection &, const QIt
         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),

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 +566,8 @@ 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 +610,15 @@ 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);
+        NPNR_ASSERT(switches_locked[chip_info->pip_data[pip.index].switch_index] == WireId());
-
-        pip_to_net[pip.index] = net;
-        switches_locked[chip_info->pip_data[pip.index].switch_index] = net;
 
         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 +630,7 @@ 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 +639,39 @@ 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 +680,21 @@ 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());
+        if (ice40_pip_hard_unavail(pip))
-        return switches_locked[chip_info->pip_data[pip.index].switch_index];
+            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

ice40/archdefs.h

@@ -66,6 +66,7 @@ struct BelId
 
     bool operator==(const BelId &other) const { return index == other.index; }
     bool operator!=(const BelId &other) const { return index != other.index; }
+    bool operator<(const BelId &other) const { return index < other.index; }
 };
 
 struct WireId
@@ -74,6 +75,7 @@ struct WireId
 
     bool operator==(const WireId &other) const { return index == other.index; }
     bool operator!=(const WireId &other) const { return index != other.index; }
+    bool operator<(const WireId &other) const { return index < other.index; }
 };
 
 struct PipId
@@ -82,6 +84,7 @@ struct PipId
 
     bool operator==(const PipId &other) const { return index == other.index; }
     bool operator!=(const PipId &other) const { return index != other.index; }
+    bool operator<(const PipId &other) const { return index < other.index; }
 };
 
 struct GroupId

ice40/main.cc

@@ -43,7 +43,7 @@ class Ice40CommandHandler : public CommandHandler
     void customBitstream(Context *ctx) override;
 
   protected:
-    po::options_description getArchOptions();
+    po::options_description getArchOptions() override;
 };
 
 Ice40CommandHandler::Ice40CommandHandler(int argc, char **argv) : CommandHandler(argc, argv) {}