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-rw-r--r--common/nextpnr.h1
-rw-r--r--common/placer1.cc11
-rw-r--r--common/router1.cc4
-rw-r--r--common/timing.cc173
-rw-r--r--common/timing.h8
-rw-r--r--ecp5/arch.cc2
-rw-r--r--ecp5/arch.h1
-rw-r--r--ecp5/main.cc6
-rw-r--r--generic/arch.cc2
-rw-r--r--generic/arch.h1
-rw-r--r--ice40/arch.cc31
-rw-r--r--ice40/arch.h1
-rw-r--r--ice40/main.cc6
13 files changed, 205 insertions, 42 deletions
diff --git a/common/nextpnr.h b/common/nextpnr.h
index 908b8266..38a313fd 100644
--- a/common/nextpnr.h
+++ b/common/nextpnr.h
@@ -475,6 +475,7 @@ 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 ee7225b5..c677a22a 100644
--- a/common/placer1.cc
+++ b/common/placer1.cc
@@ -152,6 +152,7 @@ class SAPlacer
}
int n_no_progress = 0;
+ wirelen_t min_metric = curr_metric;
double avg_metric = curr_metric;
temp = 10000;
@@ -177,6 +178,11 @@ 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;
@@ -230,6 +236,8 @@ class SAPlacer
diameter *= post_legalise_dia_scale;
ctx->shuffle(autoplaced);
assign_budget(ctx);
+ } else {
+ assign_budget(ctx, true /* quiet */);
}
// Recalculate total metric entirely to avoid rounding errors
@@ -264,6 +272,7 @@ class SAPlacer
}
}
}
+ timing_analysis(ctx, true /* print_fmax */);
ctx->unlock();
return true;
}
@@ -379,8 +388,6 @@ 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 4ef7df64..0bd257fd 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()));
+ assign_budget(ctx, true /* quiet */);
+
bool printNets = ctx->verbose && (jobQueue.size() < 10);
while (!jobQueue.empty()) {
@@ -811,6 +814,7 @@ bool router1(Context *ctx)
#ifndef NDEBUG
ctx->check();
#endif
+ timing_analysis(ctx, true /* print_fmax */, true /* print_path */);
ctx->unlock();
return true;
} catch (log_execution_error_exception) {
diff --git a/common/timing.cc b/common/timing.cc
index 4486fc24..b1a5619d 100644
--- a/common/timing.cc
+++ b/common/timing.cc
@@ -22,19 +22,29 @@
#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::list<const PortRef *> PortRefList;
+
+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)
+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;
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;
+ if (slack < min_slack) {
+ min_slack = slack;
+ if (crit_path)
+ *crit_path = *current_path;
+ }
} else {
// Default to the path ending here, if no further paths found
value = slack / path_length;
@@ -47,74 +57,165 @@ 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.maxDelay());
+ 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);
}
}
}
}
}
-
- if (value < user.budget) {
- user.budget = 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, bool update, delay_t &min_slack,
+ PortRefList *current_path, PortRefList *crit_path)
{
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];
+ if (crit_path)
+ current_path->push_back(&usr);
+ // If budget override is less than existing budget, then do not increment path length
+ int pl = path_length + 1;
+ auto budget = ctx->getBudgetOverride(net, i, net_budget);
+ if (budget < net_budget) {
+ net_budget = budget;
+ pl = std::max(1, path_length);
+ }
+ auto delay = ctx->getNetinfoRouteDelay(net, i);
+ net_budget = std::min(
+ net_budget, follow_user_port(ctx, usr, pl, slack - delay, update, min_slack, current_path, crit_path));
+ if (update)
+ usr.budget = std::min(usr.budget, delay + net_budget);
+ if (crit_path)
+ current_path->pop_back();
}
return net_budget;
}
-void assign_budget(Context *ctx)
+static delay_t walk_paths(Context *ctx, bool update, PortRefList *crit_path)
{
- log_break();
- log_info("Annotating ports with timing budgets\n");
- // Clear delays to a very high value first
delay_t default_slack = delay_t(1.0e12 / ctx->target_freq);
- for (auto &net : ctx->nets) {
- for (auto &usr : net.second->users) {
- usr.budget = default_slack;
- }
- }
- // Go through all clocked drivers and set up paths
+ delay_t min_slack = default_slack;
+
+ PortRefList current_path;
+
+ // Go through all clocked drivers and distribute the available path
+ // slack evenly into the budget of every sink on the path ---
+ // record this value into the UpdateMap
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 = delay_t(1.0e12 / ctx->target_freq); // TODO: clock constraints
- DelayInfo clkToQ;
+ delay_t slack = default_slack; // TODO: clock constraints
+ delay_t clkToQ;
if (ctx->getCellDelay(cell.second.get(), clock_domain, port.first, clkToQ))
slack -= clkToQ.maxDelay();
if (port.second.net)
- follow_net(ctx, port.second.net, 0, slack);
+ follow_net(ctx, port.second.net, 0, slack, update, min_slack, &current_path, crit_path);
}
}
}
}
- // Post-allocation check
+ return min_slack;
+}
+
+void assign_budget(Context *ctx, bool quiet)
+{
+ if (!quiet) {
+ log_break();
+ log_info("Annotating ports with timing budgets\n");
+ }
+
+ // Clear delays to a very high value first
+ delay_t default_slack = delay_t(1.0e12 / ctx->target_freq);
for (auto &net : ctx->nets) {
- for (auto user : net.second->users) {
- if (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));
- if (ctx->verbose)
- 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));
+ for (auto &usr : net.second->users) {
+ usr.budget = default_slack;
+ }
+ }
+
+ delay_t min_slack = walk_paths(ctx, true, nullptr);
+
+ if (!quiet || 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",
+ user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
+ ctx->getDelayNS(user.budget));
+ else if (ctx->verbose)
+ 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));
+ }
}
}
- log_info("Checksum: 0x%08x\n", ctx->checksum());
+ // If user has not specified a frequency, dynamically adjust the target
+ // frequency to be the current maximum
+ if (!ctx->user_freq) {
+ 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);
+ }
+
+ if (!quiet)
+ log_info("Checksum: 0x%08x\n", ctx->checksum());
+}
+
+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 = walk_paths(ctx, false, &crit_path);
+ if (print_path) {
+ delay_t total = 0;
+ log_break();
+ log_info("Critical path report:\n");
+ log_info("curr total\n");
+ auto &front = crit_path.front();
+ auto &front_port = front->cell->ports.at(front->port);
+ auto &front_driver = front_port.net->driver;
+ auto last_port = ctx->getPortClock(front_driver.cell, front_driver.port);
+ for (auto sink : crit_path) {
+ auto sink_cell = sink->cell;
+ auto &port = sink_cell->ports.at(sink->port);
+ auto net = port.net;
+ unsigned i = 0;
+ for (auto &usr : net->users)
+ if (&usr == sink)
+ break;
+ else
+ ++i;
+ auto &driver = net->driver;
+ auto driver_cell = driver.cell;
+ delay_t comb_delay;
+ ctx->getCellDelay(sink_cell, last_port, driver.port, comb_delay);
+ total += comb_delay;
+ log_info("%4d %4d Source %s.%s\n", comb_delay, total, driver_cell->name.c_str(ctx),
+ driver.port.c_str(ctx));
+ delay_t net_delay = ctx->getNetinfoRouteDelay(net, i);
+ total += net_delay;
+ auto driver_loc = ctx->getBelLocation(driver_cell->bel);
+ auto sink_loc = ctx->getBelLocation(sink_cell->bel);
+ log_info("%4d %4d Net %s budget %d (%d,%d) -> (%d,%d)\n", net_delay, total, net->name.c_str(ctx),
+ sink->budget, driver_loc.x, driver_loc.y, sink_loc.x, sink_loc.y);
+ log_info(" Sink %s.%s\n", sink_cell->name.c_str(ctx), sink->port.c_str(ctx));
+ last_port = sink->port;
+ }
+ log_break();
+ }
+ if (print_fmax)
+ log_info("estimated Fmax = %.2f MHz\n", 1e6 / (default_slack - min_slack));
+ return min_slack;
}
NEXTPNR_NAMESPACE_END
diff --git a/common/timing.h b/common/timing.h
index 025e4a76..d0159d5c 100644
--- a/common/timing.h
+++ b/common/timing.h
@@ -24,8 +24,12 @@
NEXTPNR_NAMESPACE_BEGIN
-// Assign "budget" values for all user ports in the design
-void assign_budget(Context *ctx);
+// Evenly redistribute the total path slack amongst all sinks on each path
+void assign_budget(Context *ctx, bool quiet = false);
+
+// Perform timing analysis and return the minimum path slack,
+// optionally, print out the fmax and critical path
+delay_t timing_analysis(Context *ctx, bool print_fmax = false, bool print_path = false);
NEXTPNR_NAMESPACE_END
diff --git a/ecp5/arch.cc b/ecp5/arch.cc
index 2b40e79a..36cefded 100644
--- a/ecp5/arch.cc
+++ b/ecp5/arch.cc
@@ -413,6 +413,8 @@ delay_t Arch::estimateDelay(WireId src, WireId dst) const
return 200 * (abs(src.location.x - dst.location.x) + abs(src.location.y - dst.location.y));
}
+delay_t Arch::getBudgetOverride(NetInfo *net_info, int user_idx, delay_t budget) const { return budget; }
+
// -----------------------------------------------------------------------
bool Arch::place() { return placer1(getCtx()); }
diff --git a/ecp5/arch.h b/ecp5/arch.h
index 2421428f..df0df311 100644
--- a/ecp5/arch.h
+++ b/ecp5/arch.h
@@ -780,6 +780,7 @@ struct Arch : BaseCtx
delay_t getRipupDelayPenalty() const { return 200; }
float getDelayNS(delay_t v) const { return v * 0.001; }
uint32_t getDelayChecksum(delay_t v) const { return v; }
+ delay_t getBudgetOverride(NetInfo *net_info, int user_idx, delay_t budget) const;
// -------------------------------------------------
diff --git a/ecp5/main.cc b/ecp5/main.cc
index 90096855..68660ced 100644
--- a/ecp5/main.cc
+++ b/ecp5/main.cc
@@ -169,8 +169,12 @@ int main(int argc, char *argv[])
if (!ctx->pack() && !ctx->force)
log_error("Packing design failed.\n");
- if (vm.count("freq"))
+ if (vm.count("freq")) {
ctx->target_freq = vm["freq"].as<double>() * 1e6;
+ ctx->user_freq = true;
+ } else {
+ log_warning("Target frequency not specified. Will optimise for max frequency.\n");
+ }
assign_budget(ctx.get());
ctx->check();
print_utilisation(ctx.get());
diff --git a/generic/arch.cc b/generic/arch.cc
index 892bb0fd..daaa8118 100644
--- a/generic/arch.cc
+++ b/generic/arch.cc
@@ -403,6 +403,8 @@ delay_t Arch::estimateDelay(WireId src, WireId dst) const
return (dx + dy) * grid_distance_to_delay;
}
+delay_t Arch::getBudgetOverride(NetInfo *net_info, int user_idx, delay_t budget) const { return budget; }
+
// ---------------------------------------------------------------
bool Arch::place() { return placer1(getCtx()); }
diff --git a/generic/arch.h b/generic/arch.h
index 9a0da75b..de06f730 100644
--- a/generic/arch.h
+++ b/generic/arch.h
@@ -198,6 +198,7 @@ struct Arch : BaseCtx
delay_t getRipupDelayPenalty() const { return 1.0; }
float getDelayNS(delay_t v) const { return v; }
uint32_t getDelayChecksum(delay_t v) const { return 0; }
+ delay_t getBudgetOverride(NetInfo *net_info, int user_idx, delay_t budget) const;
bool pack() { return true; }
bool place();
diff --git a/ice40/arch.cc b/ice40/arch.cc
index f3004155..e15abdd1 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -618,9 +618,40 @@ delay_t Arch::estimateDelay(WireId src, WireId dst) const
// offset = 500;
// }
+ // Estimate for output mux
+ for (const auto &bp : getWireBelPins(src)) {
+ if (bp.pin == PIN_O && getBelType(bp.bel) == TYPE_ICESTORM_LC) {
+ offset += 330;
+ break;
+ }
+ }
+
+ // Estimate for input mux
+ for (const auto &bp : getWireBelPins(dst)) {
+ if ((bp.pin == PIN_I0 || bp.pin == PIN_I1 || bp.pin == PIN_I2 || bp.pin == PIN_I3) &&
+ getBelType(bp.bel) == TYPE_ICESTORM_LC) {
+ offset += 260;
+ break;
+ }
+ }
+
return xscale * abs(xd) + yscale * abs(yd) + offset;
}
+delay_t Arch::getBudgetOverride(NetInfo *net_info, int user_idx, delay_t budget) const
+{
+ const auto &driver = net_info->driver;
+ if (driver.port == id_cout) {
+ const auto &sink = net_info->users[user_idx];
+ auto driver_loc = getBelLocation(driver.cell->bel);
+ auto sink_loc = getBelLocation(sink.cell->bel);
+ if (driver_loc.y == sink_loc.y)
+ return 0;
+ return 250;
+ }
+ return budget;
+}
+
// -----------------------------------------------------------------------
bool Arch::place() { return placer1(getCtx()); }
diff --git a/ice40/arch.h b/ice40/arch.h
index 7efa733c..f81fd21d 100644
--- a/ice40/arch.h
+++ b/ice40/arch.h
@@ -701,6 +701,7 @@ struct Arch : BaseCtx
delay_t getRipupDelayPenalty() const { return 200; }
float getDelayNS(delay_t v) const { return v * 0.001; }
uint32_t getDelayChecksum(delay_t v) const { return v; }
+ delay_t getBudgetOverride(NetInfo *net_info, int user_idx, delay_t budget) const;
// -------------------------------------------------
diff --git a/ice40/main.cc b/ice40/main.cc
index 32815b26..865eea9e 100644
--- a/ice40/main.cc
+++ b/ice40/main.cc
@@ -363,8 +363,12 @@ int main(int argc, char *argv[])
}
}
- if (vm.count("freq"))
+ if (vm.count("freq")) {
ctx->target_freq = vm["freq"].as<double>() * 1e6;
+ ctx->user_freq = true;
+ } else {
+ log_warning("Target frequency not specified. Will optimise for max frequency.\n");
+ }
ctx->timing_driven = true;
if (vm.count("no-tmdriv"))
generated by cgit v1.2.3 (git 2.25.1) at 2024-08-25 10:41:04 +0000