Make ice40::Arch thread-safe

We move all non-chip data to be private and guard them with an R/W
mutex.

We then modify all calls that access these fields to lock/shared_lock
the mutex as required.

Profiling the code before and after is an exercise left to the reader
:).

3 files changed, 44 insertions, 11 deletions

diff --git a/ice40/arch.cc b/ice40/arch.cc
index 786bf686..88a900d8 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -241,6 +241,7 @@ IdString Arch::archArgsToId(ArchArgs args) const
 
 BelId Arch::getBelByName(IdString name) const
 {
+    boost::lock_guard<boost::shared_mutex> lock(mtx_);
     BelId ret;
 
     if (bel_by_name.empty()) {
@@ -276,6 +277,7 @@ BelRange Arch::getBelsAtSameTile(BelId bel) const
 WireId Arch::getWireBelPin(BelId bel, PortPin pin) const
 {
     WireId ret;
+    boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
 
     NPNR_ASSERT(bel != BelId());
 
@@ -296,6 +298,7 @@ WireId Arch::getWireBelPin(BelId bel, PortPin pin) const
 WireId Arch::getWireByName(IdString name) const
 {
     WireId ret;
+    boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
 
     if (wire_by_name.empty()) {
         for (int i = 0; i < chip_info->num_wires; i++)
@@ -314,6 +317,7 @@ WireId Arch::getWireByName(IdString name) const
 PipId Arch::getPipByName(IdString name) const
 {
     PipId ret;
+    boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
 
     if (pip_by_name.empty()) {
         for (int i = 0; i < chip_info->num_pips; i++) {
@@ -372,6 +376,8 @@ std::string Arch::getBelPackagePin(BelId bel) const
 
 // -----------------------------------------------------------------------
 
+// TODO(cliffordvienna): lock all of this
+
 GroupId Arch::getGroupByName(IdString name) const
 {
     for (auto g : getGroups())
@@ -488,6 +494,7 @@ DecalXY Arch::getGroupDecal(GroupId group) const
 
 std::vector<GraphicElement> Arch::getDecalGraphics(DecalId decal) const
 {
+    boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
     std::vector<GraphicElement> ret;
 
     if (decal.type == DecalId::TYPE_FRAME) {
diff --git a/ice40/arch.h b/ice40/arch.h
index 04de5178..410df48b 100644
--- a/ice40/arch.h
+++ b/ice40/arch.h
@@ -21,6 +21,9 @@
 #error Include "arch.h" via "nextpnr.h" only.
 #endif
 
+#include <boost/thread/shared_lock_guard.hpp>
+#include <boost/thread/shared_mutex.hpp>
+
 NEXTPNR_NAMESPACE_BEGIN
 
 /**** Everything in this section must be kept in sync with chipdb.py ****/
@@ -324,8 +327,17 @@ struct ArchArgs
     std::string package;
 };
 
-struct Arch : BaseCtx
+class Arch : public BaseCtx
 {
+private:
+    // All of the following...
+    std::vector<IdString> bel_to_cell;
+    std::vector<IdString> wire_to_net;
+    std::vector<IdString> pip_to_net;
+    std::vector<IdString> switches_locked;
+    // ... are guarded by the following lock:
+    mutable boost::shared_mutex mtx_;
+public:
     const ChipInfoPOD *chip_info;
     const PackageInfoPOD *package_info;
 
@@ -333,11 +345,6 @@ struct Arch : BaseCtx
     mutable std::unordered_map<IdString, int> wire_by_name;
     mutable std::unordered_map<IdString, int> pip_by_name;
 
-    std::vector<IdString> bel_to_cell;
-    std::vector<IdString> wire_to_net;
-    std::vector<IdString> pip_to_net;
-    std::vector<IdString> switches_locked;
-
     ArchArgs args;
     Arch(ArchArgs args);
 
@@ -368,6 +375,7 @@ struct Arch : BaseCtx
     {
         NPNR_ASSERT(bel != BelId());
         NPNR_ASSERT(bel_to_cell[bel.index] == IdString());
+        boost::lock_guard<boost::shared_mutex> lock(mtx_);
         bel_to_cell[bel.index] = cell;
         cells[cell]->bel = bel;
         cells[cell]->belStrength = strength;
@@ -377,6 +385,7 @@ struct Arch : BaseCtx
     {
         NPNR_ASSERT(bel != BelId());
         NPNR_ASSERT(bel_to_cell[bel.index] != IdString());
+        boost::lock_guard<boost::shared_mutex> lock(mtx_);
         cells[bel_to_cell[bel.index]]->bel = BelId();
         cells[bel_to_cell[bel.index]]->belStrength = STRENGTH_NONE;
         bel_to_cell[bel.index] = IdString();
@@ -385,18 +394,21 @@ struct Arch : BaseCtx
     bool checkBelAvail(BelId bel) const
     {
         NPNR_ASSERT(bel != BelId());
+        boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
         return bel_to_cell[bel.index] == IdString();
     }
 
     IdString getBoundBelCell(BelId bel) const
     {
         NPNR_ASSERT(bel != BelId());
+        boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
         return bel_to_cell[bel.index];
     }
 
     IdString getConflictingBelCell(BelId bel) const
     {
         NPNR_ASSERT(bel != BelId());
+        boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
         return bel_to_cell[bel.index];
     }
 
@@ -470,6 +482,8 @@ struct Arch : BaseCtx
     {
         NPNR_ASSERT(wire != WireId());
         NPNR_ASSERT(wire_to_net[wire.index] == IdString());
+        boost::lock_guard<boost::shared_mutex> lock(mtx_);
+
         wire_to_net[wire.index] = net;
         nets[net]->wires[wire].pip = PipId();
         nets[net]->wires[wire].strength = strength;
@@ -479,6 +493,7 @@ struct Arch : BaseCtx
     {
         NPNR_ASSERT(wire != WireId());
         NPNR_ASSERT(wire_to_net[wire.index] != IdString());
+        boost::lock_guard<boost::shared_mutex> lock(mtx_);
 
         auto &net_wires = nets[wire_to_net[wire.index]]->wires;
         auto it = net_wires.find(wire);
@@ -497,18 +512,24 @@ struct Arch : BaseCtx
     bool checkWireAvail(WireId wire) const
     {
         NPNR_ASSERT(wire != WireId());
+        boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
+
         return wire_to_net[wire.index] == IdString();
     }
 
     IdString getBoundWireNet(WireId wire) const
     {
         NPNR_ASSERT(wire != WireId());
+        boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
+
         return wire_to_net[wire.index];
     }
 
     IdString getConflictingWireNet(WireId wire) const
     {
         NPNR_ASSERT(wire != WireId());
+        boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
+
         return wire_to_net[wire.index];
     }
 
@@ -532,6 +553,7 @@ struct Arch : BaseCtx
         NPNR_ASSERT(pip != PipId());
         NPNR_ASSERT(pip_to_net[pip.index] == IdString());
         NPNR_ASSERT(switches_locked[chip_info->pip_data[pip.index].switch_index] == IdString());
+        boost::lock_guard<boost::shared_mutex> lock(mtx_);
 
         pip_to_net[pip.index] = net;
         switches_locked[chip_info->pip_data[pip.index].switch_index] = net;
@@ -549,6 +571,7 @@ struct Arch : BaseCtx
         NPNR_ASSERT(pip != PipId());
         NPNR_ASSERT(pip_to_net[pip.index] != IdString());
         NPNR_ASSERT(switches_locked[chip_info->pip_data[pip.index].switch_index] != IdString());
+        boost::lock_guard<boost::shared_mutex> lock(mtx_);
 
         WireId dst;
         dst.index = chip_info->pip_data[pip.index].dst;
@@ -563,18 +586,21 @@ struct Arch : BaseCtx
     bool checkPipAvail(PipId pip) const
     {
         NPNR_ASSERT(pip != PipId());
+        boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
         return switches_locked[chip_info->pip_data[pip.index].switch_index] == IdString();
     }
 
     IdString getBoundPipNet(PipId pip) const
     {
         NPNR_ASSERT(pip != PipId());
+        boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
         return pip_to_net[pip.index];
     }
 
     IdString getConflictingPipNet(PipId pip) const
     {
         NPNR_ASSERT(pip != PipId());
+        boost::shared_lock_guard<boost::shared_mutex> lock(mtx_);
         return switches_locked[chip_info->pip_data[pip.index].switch_index];
     }
 
diff --git a/ice40/bitstream.cc b/ice40/bitstream.cc
index a62c6c09..58a59366 100644
--- a/ice40/bitstream.cc
+++ b/ice40/bitstream.cc
@@ -128,7 +128,7 @@ void write_asc(const Context *ctx, std::ostream &out)
     }
     // Set pips
     for (auto pip : ctx->getPips()) {
-        if (ctx->pip_to_net[pip.index] != IdString()) {
+        if (ctx->getBoundPipNet(pip) != IdString()) {
             const PipInfoPOD &pi = ci.pip_data[pip.index];
             const SwitchInfoPOD &swi = bi.switches[pi.switch_index];
             for (int i = 0; i < swi.num_bits; i++) {
@@ -199,8 +199,8 @@ void write_asc(const Context *ctx, std::ostream &out)
             NPNR_ASSERT(iez != -1);
 
             bool input_en = false;
-            if ((ctx->wire_to_net[ctx->getWireBelPin(bel, PIN_D_IN_0).index] != IdString()) ||
-                (ctx->wire_to_net[ctx->getWireBelPin(bel, PIN_D_IN_1).index] != IdString())) {
+            if (!ctx->checkWireAvail(ctx->getWireBelPin(bel, PIN_D_IN_0)) ||
+                !ctx->checkWireAvail(ctx->getWireBelPin(bel, PIN_D_IN_1))) {
                 input_en = true;
             }
 
@@ -271,7 +271,7 @@ void write_asc(const Context *ctx, std::ostream &out)
     }
     // Set config bits in unused IO and RAM
     for (auto bel : ctx->getBels()) {
-        if (ctx->bel_to_cell[bel.index] == IdString() && ctx->getBelType(bel) == TYPE_SB_IO) {
+        if (ctx->checkBelAvail(bel) && ctx->getBelType(bel) == TYPE_SB_IO) {
             const TileInfoPOD &ti = bi.tiles_nonrouting[TILE_IO];
             const BelInfoPOD &beli = ci.bel_data[bel.index];
             int x = beli.x, y = beli.y, z = beli.z;
@@ -284,7 +284,7 @@ void write_asc(const Context *ctx, std::ostream &out)
                     set_config(ti, config.at(iey).at(iex), "IoCtrl.REN_" + std::to_string(iez), false);
                 }
             }
-        } else if (ctx->bel_to_cell[bel.index] == IdString() && ctx->getBelType(bel) == TYPE_ICESTORM_RAM) {
+        } else if (ctx->checkBelAvail(bel) && ctx->getBelType(bel) == TYPE_ICESTORM_RAM) {
             const BelInfoPOD &beli = ci.bel_data[bel.index];
             int x = beli.x, y = beli.y;
             const TileInfoPOD &ti = bi.tiles_nonrouting[TILE_RAMB];