Remove isValidBelForCell

This Arch API dates from when we were first working out how to
implement placement validity checking, and in practice is little used by
the core parts of placer1/HeAP and the Arch implementation involves a
lot of duplication with isBelLocationValid.

In the short term; placement validity checking is better served by the
combination of checkBelAvail and isValidBelForCellType before placement;
followed by isBelLocationValid after placement (potentially after
moving/swapping multiple cells).

Longer term, removing this API makes things a bit cleaner for a new
validity checking API.

Signed-off-by: gatecat <gatecat@ds0.me>

4 files changed, 32 insertions, 58 deletions

diff --git a/ecp5/arch.h b/ecp5/arch.h
index d5edd88e..83928256 100644
--- a/ecp5/arch.h
+++ b/ecp5/arch.h
@@ -864,7 +864,6 @@ struct Arch : BaseArch<ArchRanges>
 
     // -------------------------------------------------
     // Placement validity checks
-    bool isValidBelForCell(CellInfo *cell, BelId bel) const override;
     bool isBelLocationValid(BelId bel) const override;
 
     // Helper function for above
diff --git a/ecp5/arch_place.cc b/ecp5/arch_place.cc
index 668b3141..5565a01c 100644
--- a/ecp5/arch_place.cc
+++ b/ecp5/arch_place.cc
@@ -82,38 +82,14 @@ bool Arch::isBelLocationValid(BelId bel) const
         return slices_compatible(bel_cells);
     } else {
         CellInfo *cell = getBoundBelCell(bel);
-        if (cell == nullptr)
+        if (cell == nullptr) {
+            return true;
+        } else if (cell->type == id_DCUA || cell->type == id_EXTREFB || cell->type == id_PCSCLKDIV) {
+            return args.type != ArchArgs::LFE5U_25F && args.type != ArchArgs::LFE5U_45F &&
+                   args.type != ArchArgs::LFE5U_85F;
+        } else {
             return true;
-        else
-            return isValidBelForCell(cell, bel);
-    }
-}
-
-bool Arch::isValidBelForCell(CellInfo *cell, BelId bel) const
-{
-    if (cell->type == id_TRELLIS_SLICE) {
-        NPNR_ASSERT(getBelType(bel) == id_TRELLIS_SLICE);
-
-        std::vector<const CellInfo *> bel_cells;
-        Loc bel_loc = getBelLocation(bel);
-
-        if (cell->sliceInfo.has_l6mux && ((bel_loc.z % 2) == 1))
-            return false;
-
-        for (auto bel_other : getBelsByTile(bel_loc.x, bel_loc.y)) {
-            CellInfo *cell_other = getBoundBelCell(bel_other);
-            if (cell_other != nullptr && bel_other != bel) {
-                bel_cells.push_back(cell_other);
-            }
         }
-
-        bel_cells.push_back(cell);
-        return slices_compatible(bel_cells);
-    } else if (cell->type == id_DCUA || cell->type == id_EXTREFB || cell->type == id_PCSCLKDIV) {
-        return args.type != ArchArgs::LFE5U_25F && args.type != ArchArgs::LFE5U_45F && args.type != ArchArgs::LFE5U_85F;
-    } else {
-        // other checks
-        return true;
     }
 }
 
diff --git a/ecp5/arch_pybindings.cc b/ecp5/arch_pybindings.cc
index e1adbb46..5218ce36 100644
--- a/ecp5/arch_pybindings.cc
+++ b/ecp5/arch_pybindings.cc
@@ -44,9 +44,6 @@ void arch_wrap_python(py::module &m)
                            .def("place", &Context::place)
                            .def("route", &Context::route);
 
-    fn_wrapper_2a<Context, decltype(&Context::isValidBelForCell), &Context::isValidBelForCell, pass_through<bool>,
-                  addr_and_unwrap<CellInfo>, conv_from_str<BelId>>::def_wrap(ctx_cls, "isValidBelForCell");
-
     typedef std::unordered_map<IdString, std::unique_ptr<CellInfo>> CellMap;
     typedef std::unordered_map<IdString, std::unique_ptr<NetInfo>> NetMap;
     typedef std::unordered_map<IdString, IdString> AliasMap;
diff --git a/ecp5/globals.cc b/ecp5/globals.cc
index 1a0b7f2f..36bec64c 100644
--- a/ecp5/globals.cc
+++ b/ecp5/globals.cc
@@ -403,33 +403,35 @@ class Ecp5GlobalRouter
         bool dedicated_routing = false;
         for (auto bel : ctx->getBels()) {
             if (ctx->getBelType(bel) == id_DCCA && ctx->checkBelAvail(bel)) {
-                if (ctx->isValidBelForCell(dcc, bel)) {
-                    std::string belname = ctx->loc_info(bel)->bel_data[bel.index].name.get();
-                    if (belname.at(0) == 'D' && using_ce)
-                        continue; // don't allow DCCs with CE at center
-                    ctx->bindBel(bel, dcc, STRENGTH_LOCKED);
-                    wirelen_t wirelen = get_dcc_wirelen(dcc, dedicated_routing);
-                    if (wirelen < best_wirelen) {
-                        if (dedicated_routing) {
-                            best_bel_pclkcib = WireId();
-                        } else {
-                            bool found_pclkcib = false;
-                            for (WireId pclkcib : get_candidate_pclkcibs(bel)) {
-                                if (used_pclkcib.count(pclkcib))
-                                    continue;
-                                found_pclkcib = true;
-                                best_bel_pclkcib = pclkcib;
-                                break;
-                            }
-                            if (!found_pclkcib)
-                                goto pclkcib_fail;
+                std::string belname = ctx->loc_info(bel)->bel_data[bel.index].name.get();
+                if (belname.at(0) == 'D' && using_ce)
+                    continue; // don't allow DCCs with CE at center
+                ctx->bindBel(bel, dcc, STRENGTH_LOCKED);
+                if (!ctx->isBelLocationValid(bel)) {
+                    ctx->unbindBel(bel);
+                    continue;
+                }
+                wirelen_t wirelen = get_dcc_wirelen(dcc, dedicated_routing);
+                if (wirelen < best_wirelen) {
+                    if (dedicated_routing) {
+                        best_bel_pclkcib = WireId();
+                    } else {
+                        bool found_pclkcib = false;
+                        for (WireId pclkcib : get_candidate_pclkcibs(bel)) {
+                            if (used_pclkcib.count(pclkcib))
+                                continue;
+                            found_pclkcib = true;
+                            best_bel_pclkcib = pclkcib;
+                            break;
                         }
-                        best_bel = bel;
-                        best_wirelen = wirelen;
+                        if (!found_pclkcib)
+                            goto pclkcib_fail;
                     }
-                pclkcib_fail:
-                    ctx->unbindBel(bel);
+                    best_bel = bel;
+                    best_wirelen = wirelen;
                 }
+            pclkcib_fail:
+                ctx->unbindBel(bel);
             }
         }
         NPNR_ASSERT(best_bel != BelId());