diff options
| -rw-r--r-- | ice40/pack.cc | 50 |
1 files changed, 40 insertions, 10 deletions
diff --git a/ice40/pack.cc b/ice40/pack.cc index 08f66369..fc182e98 100644 --- a/ice40/pack.cc +++ b/ice40/pack.cc @@ -439,7 +439,15 @@ static void pack_io(Context *ctx) } } -static void insert_global(Context *ctx, NetInfo *net, bool is_reset, bool is_cen) +// Return true if a port counts as "logic" for global promotion +static bool is_logic_port(BaseCtx *ctx, const PortRef &port) +{ + if (is_clock_port(ctx, port) || is_reset_port(ctx, port) || is_enable_port(ctx, port)) + return false; + return !is_sb_io(ctx, port.cell) && !is_sb_pll40(ctx, port.cell) && !is_sb_pll40_pad(ctx, port.cell) && port.cell->type != ctx->id("SB_GB"); +} + +static void insert_global(Context *ctx, NetInfo *net, bool is_reset, bool is_cen, bool is_logic) { std::string glb_name = net->name.str(ctx) + std::string("_$glb_") + (is_reset ? "sr" : (is_cen ? "ce" : "clk")); std::unique_ptr<CellInfo> gb = create_ice_cell(ctx, ctx->id("SB_GB"), "$gbuf_" + glb_name); @@ -458,7 +466,7 @@ static void insert_global(Context *ctx, NetInfo *net, bool is_reset, bool is_cen std::vector<PortRef> keep_users; for (auto user : net->users) { if (is_clock_port(ctx, user) || (is_reset && is_reset_port(ctx, user)) || - (is_cen && is_enable_port(ctx, user))) { + (is_cen && is_enable_port(ctx, user)) || (is_logic && is_logic_port(ctx, user))) { user.cell->ports[user.port].net = glbnet.get(); glbnet->users.push_back(user); } else { @@ -474,8 +482,9 @@ static void insert_global(Context *ctx, NetInfo *net, bool is_reset, bool is_cen static void promote_globals(Context *ctx) { log_info("Promoting globals..\n"); - - std::map<IdString, int> clock_count, reset_count, cen_count; + const int logic_fanout_thresh = 15; + const int enable_fanout_thresh = 5; + std::map<IdString, int> clock_count, reset_count, cen_count, logic_count; for (auto net : sorted(ctx->nets)) { NetInfo *ni = net.second; if (ni->driver.cell != nullptr && !ctx->isGlobalNet(ni)) { @@ -490,10 +499,12 @@ static void promote_globals(Context *ctx) reset_count[net.first]++; if (is_enable_port(ctx, user)) cen_count[net.first]++; + if (is_logic_port(ctx, user)) + logic_count[net.first]++; } } } - int prom_globals = 0, prom_resets = 0, prom_cens = 0; + int prom_globals = 0, prom_resets = 0, prom_cens = 0, prom_logics = 0; int gbs_available = 8; for (auto &cell : ctx->cells) if (is_gbuf(ctx, cell.second.get())) @@ -512,29 +523,48 @@ static void promote_globals(Context *ctx) [](const std::pair<IdString, int> &a, const std::pair<IdString, int> &b) { return a.second < b.second; }); - if (global_reset->second > global_clock->second && prom_resets < 4) { + auto global_logic = std::max_element(logic_count.begin(), logic_count.end(), + [](const std::pair<IdString, int> &a, const std::pair<IdString, int> &b) { + return a.second < b.second; + }); + if (global_clock->second == 0 && prom_logics < 4 && global_logic->second > logic_fanout_thresh && + (global_logic->second > global_cen->second || prom_cens >= 4) && + (global_logic->second > global_reset->second || prom_resets >= 4)) { + NetInfo *logicnet = ctx->nets[global_logic->first].get(); + insert_global(ctx, logicnet, false, false, true); + ++prom_globals; + ++prom_logics; + clock_count.erase(logicnet->name); + reset_count.erase(logicnet->name); + cen_count.erase(logicnet->name); + logic_count.erase(logicnet->name); + } else if (global_reset->second > global_clock->second && prom_resets < 4) { NetInfo *rstnet = ctx->nets[global_reset->first].get(); - insert_global(ctx, rstnet, true, false); + insert_global(ctx, rstnet, true, false, false); ++prom_globals; ++prom_resets; clock_count.erase(rstnet->name); reset_count.erase(rstnet->name); cen_count.erase(rstnet->name); - } else if (global_cen->second > global_clock->second && prom_cens < 4) { + logic_count.erase(rstnet->name); + } else if (global_cen->second > global_clock->second && prom_cens < 4 && + global_cen->second > enable_fanout_thresh) { NetInfo *cennet = ctx->nets[global_cen->first].get(); - insert_global(ctx, cennet, false, true); + insert_global(ctx, cennet, false, true, false); ++prom_globals; ++prom_cens; clock_count.erase(cennet->name); reset_count.erase(cennet->name); cen_count.erase(cennet->name); + logic_count.erase(cennet->name); } else if (global_clock->second != 0) { NetInfo *clknet = ctx->nets[global_clock->first].get(); - insert_global(ctx, clknet, false, false); + insert_global(ctx, clknet, false, false, false); ++prom_globals; clock_count.erase(clknet->name); reset_count.erase(clknet->name); cen_count.erase(clknet->name); + logic_count.erase(clknet->name); } else { break; } |