ice40: Improve error reporting for invalid tristate usage

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

ice40/cells.cc

@@ -37,7 +37,7 @@ CellInfo *create_ice_cell(Context *ctx, IdString type, std::string name)
     CellInfo *new_cell = new CellInfo();
     if (name.empty()) {
         new_cell->name = IdString(ctx, "$nextpnr_" + type.str() + "_" +
-                                  std::to_string(auto_idx++));
+                                               std::to_string(auto_idx++));
     } else {
         new_cell->name = ctx->id(name);
     }
@@ -200,8 +200,8 @@ void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio)
     }
     NetInfo *donet = sbio->ports.at(ctx->id("D_OUT_0")).net;
     CellInfo *tbuf =
-            net_driven_by(ctx, donet, []
+            net_driven_by(ctx, donet,
-                          (const Context *ctx, const CellInfo *cell) {
+                          [](const Context *ctx, const CellInfo *cell) {
                               return cell->type == ctx->id("$_TBUF_");
                           },
                           "Y");
@@ -210,6 +210,10 @@ void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio)
         replace_port(tbuf, "A", sbio, "D_OUT_0");
         replace_port(tbuf, "E", sbio, "OUTPUT_ENABLE");
         ctx->nets.erase(donet->name);
+        if (!donet->users.empty())
+            log_error("unsupported tristate IO pattern for IO buffer '%s', "
+                      "instantiate SB_IO manually to ensure correct behaviour\n",
+                      nxio->name.c_str(ctx));
         ctx->cells.erase(tbuf->name);
     }
 }
@@ -251,7 +255,8 @@ bool is_enable_port(const Context *ctx, const PortRef &port)
 
 bool is_global_net(const Context *ctx, const NetInfo *net)
 {
-    return bool(net_driven_by(ctx, net, is_gbuf, ctx->id("GLOBAL_BUFFER_OUTPUT")));
+    return bool(
+            net_driven_by(ctx, net, is_gbuf, ctx->id("GLOBAL_BUFFER_OUTPUT")));
 }
 
 NEXTPNR_NAMESPACE_END

ice40/cells.h

@@ -27,8 +27,7 @@ NEXTPNR_NAMESPACE_BEGIN
 
 // Create a standard iCE40 cell and return it
 // Name will be automatically assigned if not specified
-CellInfo *create_ice_cell(Context *ctx, IdString type,
+CellInfo *create_ice_cell(Context *ctx, IdString type, std::string name = "");
-                          std::string name = "");
 
 // Return true if a cell is a LUT
 inline bool is_lut(const Context *ctx, const CellInfo *cell)

ice40/pack.cc

@@ -39,8 +39,8 @@ static void pack_lut_lutffs(Context *ctx)
         log_info("cell '%s' is of type '%s'\n", ci->name.c_str(ctx),
                  ci->type.c_str(ctx));
         if (is_lut(ctx, ci)) {
-            CellInfo *packed =
+            CellInfo *packed = create_ice_cell(ctx, "ICESTORM_LC",
-                    create_ice_cell(ctx, "ICESTORM_LC", ci->name.str(ctx) + "_LC");
+                                               ci->name.str(ctx) + "_LC");
             std::copy(ci->attrs.begin(), ci->attrs.end(),
                       std::inserter(packed->attrs, packed->attrs.begin()));
             packed_cells.insert(ci->name);
@@ -168,7 +168,8 @@ static void set_net_constant(const Context *ctx, NetInfo *orig,
     for (auto user : orig->users) {
         if (user.cell != nullptr) {
             CellInfo *uc = user.cell;
-            log_info("%s user %s\n", orig->name.c_str(ctx), uc->name.c_str(ctx));
+            log_info("%s user %s\n", orig->name.c_str(ctx),
+                     uc->name.c_str(ctx));
             if (is_lut(ctx, uc) && (user.port.str(ctx).at(0) == 'I') &&
                 !constval) {
                 uc->ports[user.port].net = nullptr;
@@ -206,7 +207,8 @@ static void pack_constants(Context *ctx)
 
     for (auto net : ctx->nets) {
         NetInfo *ni = net.second;
-        if (ni->driver.cell != nullptr && ni->driver.cell->type == ctx->id("GND")) {
+        if (ni->driver.cell != nullptr &&
+            ni->driver.cell->type == ctx->id("GND")) {
             set_net_constant(ctx, ni, gnd_net, false);
             gnd_used = true;
             dead_nets.push_back(net.first);
@@ -234,7 +236,8 @@ static void pack_constants(Context *ctx)
 
 static bool is_nextpnr_iob(Context *ctx, CellInfo *cell)
 {
-    return cell->type == ctx->id("$nextpnr_ibuf") || cell->type == ctx->id("$nextpnr_obuf") ||
+    return cell->type == ctx->id("$nextpnr_ibuf") ||
+           cell->type == ctx->id("$nextpnr_obuf") ||
            cell->type == ctx->id("$nextpnr_iobuf");
 }
 
@@ -250,7 +253,8 @@ static void pack_io(Context *ctx)
         CellInfo *ci = cell.second;
         if (is_nextpnr_iob(ctx, ci)) {
             CellInfo *sb = nullptr;
-            if (ci->type == ctx->id("$nextpnr_ibuf") || ci->type == ctx->id("$nextpnr_iobuf")) {
+            if (ci->type == ctx->id("$nextpnr_ibuf") ||
+                ci->type == ctx->id("$nextpnr_iobuf")) {
                 sb = net_only_drives(ctx, ci->ports.at("O").net, is_sb_io,
                                      "PACKAGE_PIN", true, ci);
 
@@ -262,8 +266,8 @@ static void pack_io(Context *ctx)
                 // Trivial case, SB_IO used. Just destroy the net and the
                 // iobuf
                 log_info("%s feeds SB_IO %s, removing %s %s.\n",
-                         ci->name.c_str(ctx), sb->name.c_str(ctx), ci->type.c_str(ctx),
+                         ci->name.c_str(ctx), sb->name.c_str(ctx),
-                         ci->name.c_str(ctx));
+                         ci->type.c_str(ctx), ci->name.c_str(ctx));
                 NetInfo *net = sb->ports.at("PACKAGE_PIN").net;
                 if (net != nullptr) {
                     ctx->nets.erase(net->name);
@@ -271,7 +275,8 @@ static void pack_io(Context *ctx)
                 }
             } else {
                 // Create a SB_IO buffer
-                sb = create_ice_cell(ctx, "SB_IO");
+                sb = create_ice_cell(ctx, "SB_IO",
+                                     ci->name.str(ctx) + "$sb_io");
                 nxio_to_sb(ctx, ci, sb);
                 new_cells.push_back(sb);
             }