Improvements in greenpak4 shreg mapping

diff --git a/passes/techmap/shregmap.cc b/passes/techmap/shregmap.cc
index 6332d59790a5e541538acb3d2e063828b28286ce..7a8495b79566625475dfedff2806d3f5f90f6064 100644 (file)
--- a/passes/techmap/shregmap.cc
+++ b/passes/techmap/shregmap.cc
@@ -26,8 +26,8 @@ PRIVATE_NAMESPACE_BEGIN
 struct ShregmapTech
 {
        virtual ~ShregmapTech() { }
-       virtual bool check_taps(const dict<int, SigBit> &taps) = 0;
-       virtual bool fixup_shreg(Cell *cell, dict<int, SigBit> &taps) = 0;
+       virtual bool analyze(vector<int> &taps) = 0;
+       virtual bool fixup(Cell *cell, dict<int, SigBit> &taps) = 0;
 };
 
 struct ShregmapOptions
@@ -54,18 +54,22 @@ struct ShregmapOptions
 
 struct ShregmapTechGreenpak4 : ShregmapTech
 {
-       bool check_taps(const dict<int, SigBit> &taps)
+       bool analyze(vector<int> &taps)
        {
+               if (GetSize(taps) > 2 && taps[0] == 0 && taps[2] < 17) {
+                       taps.clear();
+                       return true;
+               }
+
                if (GetSize(taps) > 2)
                        return false;
 
-               for (auto tap : taps)
-                       if (tap.first > 16) return false;
+               if (taps.back() > 16) return false;
 
                return true;
        }
 
-       bool fixup_shreg(Cell *cell, dict<int, SigBit> &taps)
+       bool fixup(Cell *cell, dict<int, SigBit> &taps)
        {
                auto D = cell->getPort("\\D");
                auto C = cell->getPort("\\C");
@@ -232,31 +236,47 @@ struct ShregmapWorker
 
                        Cell *first_cell = chain[cursor];
                        IdString q_port = opts.ffcells.at(first_cell->type).second;
-                       dict<int, SigBit> taps;
+                       dict<int, SigBit> taps_dict;
 
                        if (opts.tech)
                        {
+                               vector<SigBit> qbits;
+                               vector<int> taps;
+
                                for (int i = 0; i < depth; i++)
                                {
                                        Cell *cell = chain[cursor+i];
                                        auto qbit = sigmap(cell->getPort(q_port));
+                                       qbits.push_back(qbit);
 
                                        if (sigbit_with_non_chain_users.count(qbit))
-                                               taps[i] = qbit;
+                                               taps.push_back(i);
                                }
 
                                while (depth > 0)
                                {
-                                       Cell *last_cell = chain[cursor+depth-1];
-                                       taps[depth-1] = sigmap(last_cell->getPort(q_port));
-                                       if (opts.tech->check_taps(taps))
+                                       if (taps.empty() || taps.back() < depth-1)
+                                               taps.push_back(depth-1);
+
+                                       if (opts.tech->analyze(taps))
                                                break;
-                                       taps.erase(--depth);
+
+                                       taps.pop_back();
+                                       depth--;
+                               }
+
+                               depth = 0;
+                               for (auto tap : taps) {
+                                       taps_dict[tap] = qbits.at(tap);
+                                       log_assert(depth < tap+1);
+                                       depth = tap+1;
                                }
                        }
 
-                       if (depth < 2)
-                               return;
+                       if (depth < 2) {
+                               cursor++;
+                               continue;
+                       }
 
                        Cell *last_cell = chain[cursor+depth-1];
 
@@ -318,7 +338,7 @@ struct ShregmapWorker
                        first_cell->setPort(q_port, last_cell->getPort(q_port));
                        first_cell->setParam("\\DEPTH", depth);
 
-                       if (opts.tech != nullptr && !opts.tech->fixup_shreg(first_cell, taps))
+                       if (opts.tech != nullptr && !opts.tech->fixup(first_cell, taps_dict))
                                remove_cells.insert(first_cell);
 
                        for (int i = 1; i < depth; i++)
@@ -479,7 +499,6 @@ struct ShregmapPass : public Pass {
                                string tech = args[++argidx];
                                if (tech == "greenpak4") {
                                        clkpol = "pos";
-                                       opts.maxlen = 16;
                                        opts.zinit = true;
                                        opts.tech = new ShregmapTechGreenpak4;
                                } else {