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-rw-r--r--common/timing.cc96
1 files changed, 38 insertions, 58 deletions
diff --git a/common/timing.cc b/common/timing.cc
index f720b772..20cfd1b5 100644
--- a/common/timing.cc
+++ b/common/timing.cc
@@ -26,14 +26,13 @@
NEXTPNR_NAMESPACE_BEGIN
-typedef std::unordered_map<const PortInfo *, delay_t> UpdateMap;
typedef std::list<const PortRef *> PortRefList;
-static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack, UpdateMap *updates,
+static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack, bool update,
delay_t &min_slack, PortRefList *current_path, PortRefList *crit_path);
// Follow a path, returning budget to annotate
-static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length, delay_t slack, UpdateMap *updates,
+static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length, delay_t slack, bool update,
delay_t &min_slack, PortRefList *current_path, PortRefList *crit_path)
{
delay_t value;
@@ -58,7 +57,7 @@ static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length, de
if (is_path) {
NetInfo *net = port.second.net;
if (net) {
- delay_t path_budget = follow_net(ctx, net, path_length, slack - comb_delay, updates, min_slack,
+ delay_t path_budget = follow_net(ctx, net, path_length, slack - comb_delay, update, min_slack,
current_path, crit_path);
value = std::min(value, path_budget);
}
@@ -66,16 +65,10 @@ static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length, de
}
}
}
-
- if (updates) {
- auto ret = updates->emplace(&user.cell->ports.at(user.port), value);
- if (!ret.second)
- ret.first->second = std::min(value, ret.first->second);
- }
return value;
}
-static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack, UpdateMap *updates,
+static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack, bool update,
delay_t &min_slack, PortRefList *current_path, PortRefList *crit_path)
{
delay_t net_budget = slack / (path_length + 1);
@@ -92,14 +85,16 @@ static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t s
}
net_budget = std::min(net_budget,
follow_user_port(ctx, usr, pl, slack - ctx->getNetinfoRouteDelay(net, i),
- updates, min_slack, current_path, crit_path));
+ update, min_slack, current_path, crit_path));
+ if (update)
+ usr.budget = std::min(usr.budget, net_budget);
if (crit_path)
current_path->pop_back();
}
return net_budget;
}
-static delay_t compute_min_slack(Context *ctx, UpdateMap *updates, PortRefList *crit_path)
+static delay_t walk_paths(Context *ctx, bool update, PortRefList *crit_path)
{
delay_t default_slack = delay_t(1.0e12 / ctx->target_freq);
delay_t min_slack = default_slack;
@@ -119,7 +114,7 @@ static delay_t compute_min_slack(Context *ctx, UpdateMap *updates, PortRefList *
if (ctx->getCellDelay(cell.second.get(), clock_domain, port.first, clkToQ))
slack -= clkToQ;
if (port.second.net)
- follow_net(ctx, port.second.net, 0, slack, updates, min_slack, &current_path, crit_path);
+ follow_net(ctx, port.second.net, 0, slack, update, min_slack, &current_path, crit_path);
}
}
}
@@ -140,32 +135,10 @@ void assign_budget(Context *ctx)
}
}
- UpdateMap updates;
- delay_t min_slack = compute_min_slack(ctx, &updates, nullptr);
+ delay_t min_slack = walk_paths(ctx, true, nullptr);
- // If user has not specified a frequency, adjust the target frequency dynamically
- // TODO(eddieh): Tune these factors
- if (!ctx->user_freq) {
- if (min_slack < 0)
- ctx->target_freq = 1e12 / (default_slack - 0.95 * min_slack);
- else
- ctx->target_freq = 1e12 / (default_slack - 1.2 * min_slack);
- if (ctx->verbose)
- log_info("minimum slack for this assign = %d, target Fmax for next update = %.2f MHz\n", min_slack,
- ctx->target_freq / 1e6);
- }
-
- // Update the budgets
for (auto &net : ctx->nets) {
- for (size_t i = 0; i < net.second->users.size(); ++i) {
- auto &user = net.second->users[i];
- auto pi = &user.cell->ports.at(user.port);
- auto budget = ctx->getNetinfoRouteDelay(net.second.get(), i);
- auto it = updates.find(pi);
- if (it != updates.end())
- budget += it->second;
- user.budget = ctx->getBudgetOverride(net.second.get(), i, budget);
-
+ for (auto &user : net.second->users) {
// Post-update check
if (ctx->user_freq && user.budget < 0)
log_warning("port %s.%s, connected to net '%s', has negative "
@@ -180,27 +153,29 @@ void assign_budget(Context *ctx)
}
}
+ // If user has not specified a frequency, adjust the target frequency dynamically
+ // TODO(eddieh): Tune these factors
+ if (!ctx->user_freq) {
+ if (min_slack < 0)
+ ctx->target_freq = 1e12 / (default_slack - 0.95 * min_slack);
+ else
+ ctx->target_freq = 1e12 / (default_slack - 1.2 * min_slack);
+ if (ctx->verbose)
+ log_info("minimum slack for this assign = %d, target Fmax for next update = %.2f MHz\n", min_slack,
+ ctx->target_freq / 1e6);
+ }
+
log_info("Checksum: 0x%08x\n", ctx->checksum());
}
void update_budget(Context *ctx)
{
- UpdateMap updates;
- delay_t min_slack = compute_min_slack(ctx, &updates, nullptr);
-
- // Update the budgets
- for (auto &net : ctx->nets) {
- for (size_t i = 0; i < net.second->users.size(); ++i) {
- auto &user = net.second->users[i];
- auto pi = &user.cell->ports.at(user.port);
- auto budget = ctx->getNetinfoRouteDelay(net.second.get(), i);
- auto it = updates.find(pi);
- if (it != updates.end())
- budget += it->second;
- user.budget = ctx->getBudgetOverride(net.second.get(), i, budget);
+ delay_t min_slack = walk_paths(ctx, true, nullptr);
- // Post-update check
- if (ctx->verbose) {
+ if (ctx->verbose) {
+ for (auto &net : ctx->nets) {
+ for (auto &user : net.second->users) {
+ // Post-update check
if (ctx->user_freq && user.budget < 0)
log_warning("port %s.%s, connected to net '%s', has negative "
"timing budget of %fns\n",
@@ -215,21 +190,25 @@ void update_budget(Context *ctx)
}
}
- // If user has not specified a frequency, adjust the frequency dynamically:
+ // If user has not specified a frequency, adjust the target frequency dynamically
+ // TODO(eddieh): Tune these factors
if (!ctx->user_freq) {
delay_t default_slack = delay_t(1.0e12 / ctx->target_freq);
- ctx->target_freq = 1e12 / (default_slack - min_slack);
+ if (min_slack < 0)
+ ctx->target_freq = 1e12 / (default_slack - 0.95 * min_slack);
+ else
+ ctx->target_freq = 1e12 / (default_slack - 1.2 * min_slack);
if (ctx->verbose)
- log_info("minimum slack for this update = %d, target Fmax for next update = %.2f MHz\n", min_slack,
+ log_info("minimum slack for this assign = %d, target Fmax for next update = %.2f MHz\n", min_slack,
ctx->target_freq / 1e6);
}
}
-void compute_fmax(Context *ctx, bool print_fmax, bool print_path)
+delay_t timing_analysis(Context *ctx, bool print_fmax, bool print_path)
{
delay_t default_slack = delay_t(1.0e12 / ctx->target_freq);
PortRefList crit_path;
- delay_t min_slack = compute_min_slack(ctx, nullptr, &crit_path);
+ delay_t min_slack = walk_paths(ctx, false, &crit_path);
if (print_path) {
delay_t total = 0;
log_break();
@@ -267,6 +246,7 @@ void compute_fmax(Context *ctx, bool print_fmax, bool print_path)
}
if (print_fmax)
log_info("estimated Fmax = %.2f MHz\n", 1e6 / (default_slack - min_slack));
+ return min_slack;
}
NEXTPNR_NAMESPACE_END
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-20 00:22:26 +0000