aboutsummaryrefslogtreecommitdiffstats
path: root/common
diff options
context:
space:
mode:
Diffstat (limited to 'common')
-rw-r--r--common/nextpnr.h1
-rw-r--r--common/placer1.cc11
-rw-r--r--common/router1.cc3
-rw-r--r--common/timing.cc108
-rw-r--r--common/timing.h2
5 files changed, 110 insertions, 15 deletions
diff --git a/common/nextpnr.h b/common/nextpnr.h
index 1cce21c0..4d9cf5f7 100644
--- a/common/nextpnr.h
+++ b/common/nextpnr.h
@@ -466,6 +466,7 @@ struct Context : Arch, DeterministicRNG
bool force = false;
bool timing_driven = true;
float target_freq = 12e6;
+ bool user_freq = false;
Context(ArchArgs args) : Arch(args) {}
diff --git a/common/placer1.cc b/common/placer1.cc
index 4659da11..30f0057c 100644
--- a/common/placer1.cc
+++ b/common/placer1.cc
@@ -155,6 +155,7 @@ class SAPlacer
ctx->unlock();
int n_no_progress = 0;
+ wirelen_t min_metric = curr_metric;
double avg_metric = curr_metric;
temp = 10000;
@@ -180,6 +181,11 @@ class SAPlacer
}
}
+ if (curr_metric < min_metric) {
+ min_metric = curr_metric;
+ improved = true;
+ }
+
// Heuristic to improve placement on the 8k
if (improved)
n_no_progress = 0;
@@ -234,6 +240,9 @@ class SAPlacer
ctx->shuffle(autoplaced);
assign_budget(ctx);
}
+ else {
+ update_budget(ctx);
+ }
// Recalculate total metric entirely to avoid rounding errors
// accumulating over time
@@ -382,8 +391,6 @@ class SAPlacer
// SA acceptance criterea
if (delta < 0 || (temp > 1e-6 && (ctx->rng() / float(0x3fffffff)) <= std::exp(-delta / temp))) {
n_accept++;
- if (delta < 2)
- improved = true;
} else {
if (other != IdString())
ctx->unbindBel(oldBel);
diff --git a/common/router1.cc b/common/router1.cc
index fbf3c467..dbf97af7 100644
--- a/common/router1.cc
+++ b/common/router1.cc
@@ -22,6 +22,7 @@
#include "log.h"
#include "router1.h"
+#include "timing.h"
namespace {
@@ -615,6 +616,8 @@ bool router1(Context *ctx)
if (ctx->verbose || iterCnt == 1)
log_info("routing queue contains %d jobs.\n", int(jobQueue.size()));
+ update_budget(ctx);
+
bool printNets = ctx->verbose && (jobQueue.size() < 10);
while (!jobQueue.empty()) {
diff --git a/common/timing.cc b/common/timing.cc
index d91dea20..2c467961 100644
--- a/common/timing.cc
+++ b/common/timing.cc
@@ -22,19 +22,23 @@
#include <unordered_map>
#include <utility>
#include "log.h"
+#include "util.h"
NEXTPNR_NAMESPACE_BEGIN
-static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack);
+typedef std::unordered_map<const PortInfo*, delay_t> UpdateMap;
+
+static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack, UpdateMap &updates, delay_t &min_slack);
// Follow a path, returning budget to annotate
-static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length, delay_t slack)
+static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length, delay_t slack, UpdateMap &updates, delay_t &min_slack)
{
delay_t value;
if (ctx->getPortClock(user.cell, user.port) != IdString()) {
// At the end of a timing path (arguably, should check setup time
// here too)
value = slack / path_length;
+ min_slack = std::min(min_slack, value);
} else {
// Default to the path ending here, if no further paths found
value = slack / path_length;
@@ -47,7 +51,7 @@ 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);
+ delay_t path_budget = follow_net(ctx, net, path_length, slack - comb_delay, updates, min_slack);
value = std::min(value, path_budget);
}
}
@@ -55,23 +59,28 @@ static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length, de
}
}
- if (value < user.budget) {
- user.budget = value;
+ auto ret = updates.emplace(&user.cell->ports.at(user.port), value);
+ if (!ret.second && value < ret.first->second) {
+ ret.first->second = value;
}
return value;
}
-static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack)
+static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack, UpdateMap &updates, delay_t &min_slack)
{
delay_t net_budget = slack / (path_length + 1);
- for (auto &usr : net->users) {
- net_budget = std::min(net_budget, follow_user_port(ctx, usr, path_length + 1, slack));
+ for (unsigned i = 0; i < net->users.size(); ++i) {
+ auto &usr = net->users[i];
+ net_budget = std::min(net_budget, follow_user_port(ctx, usr, path_length + 1, slack - ctx->getNetinfoRouteDelay(net, i), updates, min_slack));
}
return net_budget;
}
void assign_budget(Context *ctx)
{
+ UpdateMap updates;
+ delay_t min_slack = delay_t(1.0e12 / ctx->target_freq);
+
log_break();
log_info("Annotating ports with timing budgets\n");
// Clear delays to a very high value first
@@ -81,6 +90,7 @@ void assign_budget(Context *ctx)
usr.budget = default_slack;
}
}
+ min_slack = default_slack;
// Go through all clocked drivers and set up paths
for (auto &cell : ctx->cells) {
for (auto port : cell.second->ports) {
@@ -91,17 +101,33 @@ void assign_budget(Context *ctx)
delay_t clkToQ;
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);
+ if (port.second.net) {
+ log_break();
+ follow_net(ctx, port.second.net, 0, slack, updates, min_slack);
+ }
}
}
}
}
- // Post-allocation check
+ if (!ctx->user_freq) {
+ ctx->target_freq = 1e12 / (default_slack - min_slack);
+ if (ctx->verbose)
+ log_info("minimum slack for this assign = %d, target Fmax for next update = %f\n", min_slack, ctx->target_freq/1e6);
+ }
+
+ // Update the budgets
for (auto &net : ctx->nets) {
- for (auto user : net.second->users) {
- if (user.budget < 0)
+ 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 it = updates.find(pi);
+ if (it == updates.end()) continue;
+ auto budget = ctx->getNetinfoRouteDelay(net.second.get(), i) + it->second;
+ user.budget = ctx->getBudgetOverride(net.second->driver, budget);
+
+ // 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",
user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
@@ -117,4 +143,60 @@ void assign_budget(Context *ctx)
log_info("Checksum: 0x%08x\n", ctx->checksum());
}
+void update_budget(Context *ctx)
+{
+ UpdateMap updates;
+ delay_t default_slack = delay_t(1.0e12 / ctx->target_freq);
+ delay_t min_slack = delay_t(1.0e12 / ctx->target_freq);
+
+ // Go through all clocked drivers and distribute the available path slack evenly into every budget
+ for (auto &cell : ctx->cells) {
+ for (auto& port : cell.second->ports) {
+ if (port.second.type == PORT_OUT) {
+ IdString clock_domain = ctx->getPortClock(cell.second.get(), port.first);
+ if (clock_domain != IdString()) {
+ delay_t slack = default_slack; // TODO: clock constraints
+ delay_t clkToQ;
+ 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);
+ }
+ }
+ }
+ }
+
+ if (!ctx->user_freq) {
+ ctx->target_freq = 1.05 * (1e12 / (default_slack - min_slack));
+ if (ctx->verbose)
+ log_info("minimum slack for this update = %d, target Fmax for next update = %f\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 it = updates.find(pi);
+ if (it == updates.end()) continue;
+ auto budget = ctx->getNetinfoRouteDelay(net.second.get(), i) + it->second;
+ user.budget = ctx->getBudgetOverride(net.second->driver, budget);
+
+ // Post-update check
+ if (ctx->verbose) {
+ if (ctx->user_freq && user.budget < 0)
+ log_warning("port %s.%s, connected to net '%s', has negative "
+ "timing budget of %fns\n",
+ user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
+ ctx->getDelayNS(user.budget));
+ else
+ log_info("port %s.%s, connected to net '%s', has "
+ "timing budget of %fns\n",
+ user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
+ ctx->getDelayNS(user.budget));
+ }
+ }
+ }
+}
+
NEXTPNR_NAMESPACE_END
diff --git a/common/timing.h b/common/timing.h
index 025e4a76..b5574392 100644
--- a/common/timing.h
+++ b/common/timing.h
@@ -27,6 +27,8 @@ NEXTPNR_NAMESPACE_BEGIN
// Assign "budget" values for all user ports in the design
void assign_budget(Context *ctx);
+void update_budget(Context *ctx);
+
NEXTPNR_NAMESPACE_END
#endif
generated by cgit v1.2.3 (git 2.25.1) at 2024-10-12 17:14:00 +0000