ecp5: Improve global routing robustness

Signed-off-by: David Shah <dave@ds0.me>

1 files changed, 11 insertions, 0 deletions

diff --git a/ecp5/globals.cc b/ecp5/globals.cc
index 28061e1a..550af615 100644
--- a/ecp5/globals.cc
+++ b/ecp5/globals.cc
@@ -63,6 +63,13 @@ class Ecp5GlobalRouter
         return false;
     }
 
+    bool is_logic_port(const PortRef &user)
+    {
+        if (user.cell->type == id_TRELLIS_SLICE && user.port != id_CLK && user.port != id_WCK)
+            return true;
+        return false;
+    }
+
     std::vector<NetInfo *> get_clocks()
     {
         std::unordered_map<IdString, int> clockCount;
@@ -162,6 +169,8 @@ class Ecp5GlobalRouter
             if (ctx->checkWireAvail(next)) {
                 for (auto pip : ctx->getPipsUphill(next)) {
                     WireId src = ctx->getPipSrcWire(pip);
+                    if (backtrace.count(src))
+                        continue;
                     backtrace[src] = pip;
                     upstream.push(src);
                 }
@@ -414,6 +423,8 @@ class Ecp5GlobalRouter
                     keep_users.push_back(user);
                 } else if (net->driver.cell->type == id_EXTREFB && user.cell->type == id_DCUA) {
                     keep_users.push_back(user);
+                } else if (is_logic_port(user)) {
+                    keep_users.push_back(user);
                 } else {
                     glbnet->users.push_back(user);
                     user.cell->ports.at(user.port).net = glbnet.get();