| /* |
| * nextpnr -- Next Generation Place and Route |
| * |
| * Copyright (C) 2018 David Shah <david@symbioticeda.com> |
| * |
| * Permission to use, copy, modify, and/or distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
| * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
| * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
| * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| * |
| */ |
| |
| #include "chains.h" |
| #include <algorithm> |
| #include <vector> |
| #include "cells.h" |
| #include "chain_utils.h" |
| #include "design_utils.h" |
| #include "log.h" |
| #include "place_common.h" |
| #include "util.h" |
| |
| NEXTPNR_NAMESPACE_BEGIN |
| |
| class ChainConstrainer |
| { |
| private: |
| Context *ctx; |
| // Split a carry chain into multiple legal chains |
| std::vector<CellChain> split_carry_chain(CellChain &carryc) |
| { |
| bool start_of_chain = true; |
| std::vector<CellChain> chains; |
| std::vector<const CellInfo *> tile; |
| const int max_length = (ctx->chip_info->height - 2) * 8 - 2; |
| auto curr_cell = carryc.cells.begin(); |
| while (curr_cell != carryc.cells.end()) { |
| CellInfo *cell = *curr_cell; |
| if (tile.size() >= 8) { |
| tile.clear(); |
| } |
| if (start_of_chain) { |
| tile.clear(); |
| chains.emplace_back(); |
| start_of_chain = false; |
| if (cell->ports.at(ctx->id("CIN")).net) { |
| // CIN is not constant and not part of a chain. Must feed in from fabric |
| CellInfo *feedin = make_carry_feed_in(cell, cell->ports.at(ctx->id("CIN"))); |
| chains.back().cells.push_back(feedin); |
| tile.push_back(feedin); |
| } |
| } |
| tile.push_back(cell); |
| chains.back().cells.push_back(cell); |
| bool split_chain = (!ctx->logicCellsCompatible(tile.data(), tile.size())) || |
| (int(chains.back().cells.size()) > max_length); |
| if (split_chain) { |
| CellInfo *passout = make_carry_pass_out((*(curr_cell - 1))->ports.at(ctx->id("COUT"))); |
| tile.pop_back(); |
| chains.back().cells.back() = passout; |
| start_of_chain = true; |
| } else { |
| NetInfo *carry_net = cell->ports.at(ctx->id("COUT")).net; |
| bool at_end = (curr_cell == carryc.cells.end() - 1); |
| if (carry_net != nullptr && (carry_net->users.size() > 1 || at_end)) { |
| if (carry_net->users.size() > 2 || |
| (net_only_drives(ctx, carry_net, is_lc, ctx->id("I3"), false) != |
| net_only_drives(ctx, carry_net, is_lc, ctx->id("CIN"), false)) || |
| (at_end && !net_only_drives(ctx, carry_net, is_lc, ctx->id("I3"), true))) { |
| CellInfo *passout = make_carry_pass_out(cell->ports.at(ctx->id("COUT")), |
| at_end ? nullptr : *(curr_cell + 1)); |
| chains.back().cells.push_back(passout); |
| tile.push_back(passout); |
| } |
| } |
| ++curr_cell; |
| } |
| } |
| return chains; |
| } |
| |
| // Insert a logic cell to legalise a COUT->fabric connection |
| CellInfo *make_carry_pass_out(PortInfo &cout_port, CellInfo *cin_cell = nullptr) |
| { |
| NPNR_ASSERT(cout_port.net != nullptr); |
| std::unique_ptr<CellInfo> lc = create_ice_cell(ctx, ctx->id("ICESTORM_LC")); |
| lc->params[ctx->id("LUT_INIT")] = "65280"; // 0xff00: O = I3 |
| lc->params[ctx->id("CARRY_ENABLE")] = "1"; |
| lc->ports.at(id_O).net = cout_port.net; |
| std::unique_ptr<NetInfo> co_i3_net(new NetInfo()); |
| co_i3_net->name = ctx->id(lc->name.str(ctx) + "$I3"); |
| co_i3_net->driver = cout_port.net->driver; |
| PortRef i3_r; |
| i3_r.port = id_I3; |
| i3_r.cell = lc.get(); |
| co_i3_net->users.push_back(i3_r); |
| PortRef o_r; |
| o_r.port = id_O; |
| o_r.cell = lc.get(); |
| cout_port.net->driver = o_r; |
| lc->ports.at(id_I3).net = co_i3_net.get(); |
| cout_port.net = co_i3_net.get(); |
| |
| IdString co_i3_name = co_i3_net->name; |
| NPNR_ASSERT(ctx->nets.find(co_i3_name) == ctx->nets.end()); |
| ctx->nets[co_i3_name] = std::move(co_i3_net); |
| |
| // If COUT also connects to a CIN; preserve the carry chain |
| if (cin_cell) { |
| std::unique_ptr<NetInfo> co_cin_net(new NetInfo()); |
| co_cin_net->name = ctx->id(lc->name.str(ctx) + "$COUT"); |
| |
| // Connect I1 to 1 to preserve carry chain |
| NetInfo *vcc = ctx->nets.at(ctx->id("$PACKER_VCC_NET")).get(); |
| lc->ports.at(id_I1).net = vcc; |
| PortRef i1_r; |
| i1_r.port = id_I1; |
| i1_r.cell = lc.get(); |
| vcc->users.push_back(i1_r); |
| |
| // Connect co_cin_net to the COUT of the LC |
| PortRef co_r; |
| co_r.port = id_COUT; |
| co_r.cell = lc.get(); |
| co_cin_net->driver = co_r; |
| lc->ports.at(id_COUT).net = co_cin_net.get(); |
| |
| // Find the user corresponding to the next CIN |
| int replaced_ports = 0; |
| if (ctx->debug) |
| log_info("cell: %s\n", cin_cell->name.c_str(ctx)); |
| for (auto port : {id_CIN, id_I3}) { |
| auto &usr = lc->ports.at(id_O).net->users; |
| if (ctx->debug) |
| for (auto user : usr) |
| log_info("%s.%s\n", user.cell->name.c_str(ctx), user.port.c_str(ctx)); |
| auto fnd_user = std::find_if(usr.begin(), usr.end(), |
| [&](const PortRef &pr) { return pr.cell == cin_cell && pr.port == port; }); |
| if (fnd_user != usr.end()) { |
| co_cin_net->users.push_back(*fnd_user); |
| usr.erase(fnd_user); |
| cin_cell->ports.at(port).net = co_cin_net.get(); |
| ++replaced_ports; |
| } |
| } |
| NPNR_ASSERT(replaced_ports > 0); |
| IdString co_cin_name = co_cin_net->name; |
| NPNR_ASSERT(ctx->nets.find(co_cin_name) == ctx->nets.end()); |
| ctx->nets[co_cin_name] = std::move(co_cin_net); |
| } |
| |
| IdString name = lc->name; |
| ctx->assignCellInfo(lc.get()); |
| ctx->cells[lc->name] = std::move(lc); |
| return ctx->cells[name].get(); |
| } |
| |
| // Insert a logic cell to legalise a CIN->fabric connection |
| CellInfo *make_carry_feed_in(CellInfo *cin_cell, PortInfo &cin_port) |
| { |
| NPNR_ASSERT(cin_port.net != nullptr); |
| std::unique_ptr<CellInfo> lc = create_ice_cell(ctx, ctx->id("ICESTORM_LC")); |
| lc->params[ctx->id("CARRY_ENABLE")] = "1"; |
| lc->params[ctx->id("CIN_CONST")] = "1"; |
| lc->params[ctx->id("CIN_SET")] = "1"; |
| lc->ports.at(ctx->id("I1")).net = cin_port.net; |
| cin_port.net->users.erase(std::remove_if(cin_port.net->users.begin(), cin_port.net->users.end(), |
| [cin_cell, cin_port](const PortRef &usr) { |
| return usr.cell == cin_cell && usr.port == cin_port.name; |
| })); |
| |
| PortRef i1_ref; |
| i1_ref.cell = lc.get(); |
| i1_ref.port = ctx->id("I1"); |
| lc->ports.at(ctx->id("I1")).net->users.push_back(i1_ref); |
| |
| std::unique_ptr<NetInfo> out_net(new NetInfo()); |
| out_net->name = ctx->id(lc->name.str(ctx) + "$O"); |
| |
| PortRef drv_ref; |
| drv_ref.port = ctx->id("COUT"); |
| drv_ref.cell = lc.get(); |
| out_net->driver = drv_ref; |
| lc->ports.at(ctx->id("COUT")).net = out_net.get(); |
| |
| PortRef usr_ref; |
| usr_ref.port = cin_port.name; |
| usr_ref.cell = cin_cell; |
| out_net->users.push_back(usr_ref); |
| cin_cell->ports.at(cin_port.name).net = out_net.get(); |
| |
| IdString out_net_name = out_net->name; |
| NPNR_ASSERT(ctx->nets.find(out_net_name) == ctx->nets.end()); |
| ctx->nets[out_net_name] = std::move(out_net); |
| |
| IdString name = lc->name; |
| ctx->assignCellInfo(lc.get()); |
| ctx->cells[lc->name] = std::move(lc); |
| return ctx->cells[name].get(); |
| } |
| |
| void process_carries() |
| { |
| std::vector<CellChain> carry_chains = find_chains( |
| ctx, [](const Context *ctx, const CellInfo *cell) { return is_lc(ctx, cell); }, |
| [](const Context *ctx, const |
| |
| CellInfo *cell) { |
| CellInfo *carry_prev = |
| net_driven_by(ctx, cell->ports.at(ctx->id("CIN")).net, is_lc, ctx->id("COUT")); |
| if (carry_prev != nullptr) |
| return carry_prev; |
| CellInfo *i3_prev = net_driven_by(ctx, cell->ports.at(ctx->id("I3")).net, is_lc, ctx->id("COUT")); |
| if (i3_prev != nullptr) |
| return i3_prev; |
| return (CellInfo *)nullptr; |
| }, |
| [](const Context *ctx, const CellInfo *cell) { |
| CellInfo *carry_next = |
| net_only_drives(ctx, cell->ports.at(ctx->id("COUT")).net, is_lc, ctx->id("CIN"), false); |
| if (carry_next != nullptr) |
| return carry_next; |
| CellInfo *i3_next = |
| net_only_drives(ctx, cell->ports.at(ctx->id("COUT")).net, is_lc, ctx->id("I3"), false); |
| if (i3_next != nullptr) |
| return i3_next; |
| return (CellInfo *)nullptr; |
| }); |
| std::unordered_set<IdString> chained; |
| for (auto &base_chain : carry_chains) { |
| for (auto c : base_chain.cells) |
| chained.insert(c->name); |
| } |
| // Any cells not in chains, but with carry enabled, must also be put in a single-carry chain |
| // for correct processing |
| for (auto cell : sorted(ctx->cells)) { |
| CellInfo *ci = cell.second; |
| if (chained.find(cell.first) == chained.end() && is_lc(ctx, ci) && |
| bool_or_default(ci->params, ctx->id("CARRY_ENABLE"))) { |
| CellChain sChain; |
| sChain.cells.push_back(ci); |
| chained.insert(cell.first); |
| carry_chains.push_back(sChain); |
| } |
| } |
| std::vector<CellChain> all_chains; |
| // Chain splitting |
| for (auto &base_chain : carry_chains) { |
| if (ctx->verbose) { |
| log_info("Found carry chain: \n"); |
| for (auto entry : base_chain.cells) |
| log_info(" %s\n", entry->name.c_str(ctx)); |
| log_info("\n"); |
| } |
| std::vector<CellChain> split_chains = split_carry_chain(base_chain); |
| for (auto &chain : split_chains) { |
| all_chains.push_back(chain); |
| } |
| } |
| // Actual chain placement |
| for (auto &chain : all_chains) { |
| if (ctx->verbose) |
| log_info("Placing carry chain starting at '%s'\n", chain.cells.front()->name.c_str(ctx)); |
| |
| // Place carry chain |
| chain.cells.at(0)->constr_abs_z = true; |
| chain.cells.at(0)->constr_z = 0; |
| for (int i = 1; i < int(chain.cells.size()); i++) { |
| chain.cells.at(i)->constr_x = 0; |
| chain.cells.at(i)->constr_y = (i / 8); |
| chain.cells.at(i)->constr_z = i % 8; |
| chain.cells.at(i)->constr_abs_z = true; |
| chain.cells.at(i)->constr_parent = chain.cells.at(0); |
| chain.cells.at(0)->constr_children.push_back(chain.cells.at(i)); |
| } |
| } |
| } |
| |
| public: |
| ChainConstrainer(Context *ctx) : ctx(ctx){}; |
| void constrain_chains() { process_carries(); } |
| }; |
| |
| void constrain_chains(Context *ctx) |
| { |
| log_info("Constraining chains...\n"); |
| ChainConstrainer(ctx).constrain_chains(); |
| } |
| |
| NEXTPNR_NAMESPACE_END |
