ecp5: Add criticality-based LUT permutation

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

ecp5/arch.cc

@@ -486,7 +486,7 @@ delay_t Arch::predictDelay(const NetInfo *net_info, const PortRef &sink) const
 
     int dx = abs(driver_loc.x - sink_loc.x), dy = abs(driver_loc.y - sink_loc.y);
     return (130 - 25 * args.speed) *
-           (4 + std::max(dx - 5, 0) + std::max(dy - 5, 0) + 2 * (std::min(dx, 5) + std::min(dy, 5)));
+           (6 + std::max(dx - 5, 0) + std::max(dy - 5, 0) + 2 * (std::min(dx, 5) + std::min(dy, 5)));
 }
 
 bool Arch::getBudgetOverride(const NetInfo *net_info, const PortRef &sink, delay_t &budget) const
@@ -504,7 +504,17 @@ bool Arch::getBudgetOverride(const NetInfo *net_info, const PortRef &sink, delay
 
 // -----------------------------------------------------------------------
 
+<<<<<<< HEAD
 bool Arch::place() { return placer1(getCtx(), Placer1Cfg(getCtx())); }
+=======
+bool Arch::place()
+{
+    bool result = placer_heap(getCtx());
+    if (result)
+        permute_luts();
+    return result;
+}
+>>>>>>> 136e030... lut permutation
 
 bool Arch::route()
 {

ecp5/arch.h

@@ -971,6 +971,8 @@ struct Arch : BaseCtx
 
     void assignArchInfo();
 
+    void permute_luts();
+
     std::vector<std::pair<std::string, std::string>> getTilesAtLocation(int row, int col);
     std::string getTileByTypeAndLocation(int row, int col, std::string type) const
     {

ecp5/arch_place.cc

@@ -18,8 +18,10 @@
  */
 
 #include "cells.h"
+#include "design_utils.h"
 #include "log.h"
 #include "nextpnr.h"
+#include "timing.h"
 #include "util.h"
 NEXTPNR_NAMESPACE_BEGIN
 
@@ -115,4 +117,76 @@ bool Arch::isValidBelForCell(CellInfo *cell, BelId bel) const
     }
 }
 
+void Arch::permute_luts()
+{
+    NetCriticalityMap nc;
+    get_criticalities(getCtx(), &nc);
+
+    std::unordered_map<PortInfo *, size_t> port_to_user;
+    for (auto net : sorted(nets)) {
+        NetInfo *ni = net.second;
+        for (size_t i = 0; i < ni->users.size(); i++) {
+            auto &usr = ni->users.at(i);
+            port_to_user[&(usr.cell->ports.at(usr.port))] = i;
+        }
+    }
+
+    auto proc_lut = [&](CellInfo *ci, int lut) {
+        std::vector<IdString> port_names;
+        for (int i = 0; i < 4; i++)
+            port_names.push_back(id(std::string("ABCD").substr(i, 1) + std::to_string(lut)));
+
+        std::vector<std::pair<float, int>> inputs;
+        std::vector<NetInfo *> orig_nets;
+
+        for (int i = 0; i < 4; i++) {
+            auto &port = ci->ports.at(port_names.at(i));
+            float crit = 0;
+            if (port.net != nullptr && nc.count(port.net->name)) {
+                auto &n = nc.at(port.net->name);
+                size_t usr = port_to_user.at(&port);
+                if (usr < n.criticality.size())
+                    crit = n.criticality.at(usr);
+            }
+            orig_nets.push_back(port.net);
+            inputs.emplace_back(crit, i);
+        }
+        // Least critical first (A input is slowest)
+        std::sort(inputs.begin(), inputs.end());
+        for (int i = 0; i < 4; i++) {
+            IdString p = port_names.at(i);
+            // log_info("%s %s %f\n", p.c_str(ctx), port_names.at(inputs.at(i).second).c_str(ctx), inputs.at(i).first);
+            disconnect_port(getCtx(), ci, p);
+            ci->ports.at(p).net = nullptr;
+            if (orig_nets.at(inputs.at(i).second) != nullptr) {
+                connect_port(getCtx(), orig_nets.at(inputs.at(i).second), ci, p);
+                ci->params[id(p.str(this) + "MUX")] = p.str(this);
+            } else {
+                ci->params[id(p.str(this) + "MUX")] = "1";
+            }
+        }
+        // Rewrite function
+        int old_init = int_or_default(ci->params, id("LUT" + std::to_string(lut) + "_INITVAL"), 0);
+        int new_init = 0;
+        for (int i = 0; i < 16; i++) {
+            int old_index = 0;
+            for (int k = 0; k < 4; k++) {
+                if (i & (1 << k))
+                    old_index |= (1 << inputs.at(k).second);
+            }
+            if (old_init & (1 << old_index))
+                new_init |= (1 << i);
+        }
+        ci->params[id("LUT" + std::to_string(lut) + "_INITVAL")] = std::to_string(new_init);
+    };
+
+    for (auto cell : sorted(cells)) {
+        CellInfo *ci = cell.second;
+        if (ci->type == id_TRELLIS_SLICE && str_or_default(ci->params, id("MODE"), "LOGIC") == "LOGIC") {
+            proc_lut(ci, 0);
+            proc_lut(ci, 1);
+        }
+    }
+}
+
 NEXTPNR_NAMESPACE_END

ecp5/pack.cc

@@ -27,6 +27,7 @@
 #include "design_utils.h"
 #include "globals.h"
 #include "log.h"
+#include "timing.h"
 #include "util.h"
 NEXTPNR_NAMESPACE_BEGIN