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Merge pull request #21 from daveshah1/promote_logic_globals

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ice40: Promote 'logic' globals as well as clock/enable/reset
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Clifford Wolf 2018-08-03 12:51:55 +02:00 committed by GitHub
commit 80e6b17ec9
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 40 additions and 10 deletions
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50
ice40/pack.cc
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@ -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;
}