From 8613ee17c8a673c81a9c38ac37671d50b77b9d8c Mon Sep 17 00:00:00 2001
From: Lofty <dan.ravensloft@gmail.com>
Date: Tue, 10 Feb 2026 14:08:59 +0000
Subject: [PATCH] verify inversion before/after assigning bridges

---
 himbaechel/uarch/gatemate/bitstream.cc |  7 +++++++
 himbaechel/uarch/gatemate/gatemate.cc  | 29 +++++++++++++++++++++++++-
 himbaechel/uarch/gatemate/gatemate.h   |  3 ++-
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/himbaechel/uarch/gatemate/bitstream.cc b/himbaechel/uarch/gatemate/bitstream.cc
index d4c215f5..915f0d68 100644
--- a/himbaechel/uarch/gatemate/bitstream.cc
+++ b/himbaechel/uarch/gatemate/bitstream.cc
@@ -523,4 +523,11 @@ void GateMateImpl::write_bitstream(const std::string &device, const std::string
     be.write_bitstream();
 }
 
+bool GateMateImpl::need_inversion_remove_me_later(CellInfo *cell, IdString port)
+{
+    std::ofstream out("/dev/null");
+    BitstreamBackend be(ctx, this, "", out);
+    return be.need_inversion(cell, port);
+}
+
 NEXTPNR_NAMESPACE_END
diff --git a/himbaechel/uarch/gatemate/gatemate.cc b/himbaechel/uarch/gatemate/gatemate.cc
index 361fe656..662dfba6 100644
--- a/himbaechel/uarch/gatemate/gatemate.cc
+++ b/himbaechel/uarch/gatemate/gatemate.cc
@@ -23,6 +23,7 @@
 #include "idstringlist.h"
 #include "log.h"
 #include "nextpnr_assertions.h"
+#include "nextpnr_types.h"
 #include "placer_heap.h"
 
 #define GEN_INIT_CONSTIDS
@@ -373,7 +374,8 @@ bool GateMateImpl::checkPipAvail(PipId pip) const
         if (extra_data.value == 1 && IdString(extra_data.name).in(id_C_CLKSEL, id_C_ENSEL))
             return false;
     }
-    if (!use_cp_for_cpe && extra_data.type == PipExtra::PIP_EXTRA_MUX && extra_data.resource !=0 && extra_data.resource <= PipMask::C_PY2_I) {
+    if (!use_cp_for_cpe && extra_data.type == PipExtra::PIP_EXTRA_MUX && extra_data.resource != 0 &&
+        extra_data.resource <= PipMask::C_PY2_I) {
         return false;
     }
     if (!use_bridges && extra_data.type == PipExtra::PIP_EXTRA_MUX &&
@@ -593,6 +595,18 @@ void GateMateImpl::postRoute()
 {
     int num = 0;
 
+    dict<std::pair<IdString, IdString>, bool> inversion_before_bridges;
+
+    for (auto &pair : ctx->cells) {
+        auto *cell = pair.second.get();
+        for (auto &port : cell->ports) {
+            if (port.second.type != PORT_IN)
+                continue;
+            inversion_before_bridges.insert(
+                    {std::make_pair(cell->name, port.first), need_inversion_remove_me_later(cell, port.first)});
+        }
+    }
+
     pool<IdString> nets_with_bridges;
     pool<IdString> nets_with_cplines;
 
@@ -704,6 +718,19 @@ void GateMateImpl::postRoute()
         }
     }
 
+    for (auto &pair : inversion_before_bridges) {
+        auto cell_name = pair.first.first;
+        auto port = pair.first.second;
+        auto inversion_before = pair.second;
+        auto *cell = ctx->cells.at(cell_name).get();
+        auto inversion_after = need_inversion_remove_me_later(cell, port);
+
+        if (inversion_before != inversion_after) {
+            log_error("cell '%s.%s' of type '%s' differs in inversion!\n", cell_name.c_str(ctx), port.c_str(ctx),
+                      cell->type.c_str(ctx));
+        }
+    }
+
     dict<IdString, int> cfg;
     dict<IdString, IdString> port_mapping;
     auto add_input = [&](IdString orig_port, IdString port, bool merged) -> bool {
diff --git a/himbaechel/uarch/gatemate/gatemate.h b/himbaechel/uarch/gatemate/gatemate.h
index 2d2d55e6..990a0b56 100644
--- a/himbaechel/uarch/gatemate/gatemate.h
+++ b/himbaechel/uarch/gatemate/gatemate.h
@@ -114,13 +114,14 @@ struct GateMateImpl : HimbaechelAPI
     MultiDieStrategy strategy;
     dict<int, IdString> index_to_die;
     dict<IdString, int> die_to_index;
-    dict<IdString,dict<IdString, IdString>> pass_backtrace;
+    dict<IdString, dict<IdString, IdString>> pass_backtrace;
 
   private:
     bool getChildPlacement(const BaseClusterInfo *cluster, Loc root_loc,
                            std::vector<std::pair<CellInfo *, BelId>> &placement) const;
 
     void write_bitstream(const std::string &device, const std::string &filename);
+    bool need_inversion_remove_me_later(CellInfo *cell, IdString port);
 
     void parse_ccf(const std::string &filename);