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machxo2: Global placement and clock routing from nexus
Signed-off-by: gatecat <[email protected]>
1 parent 9177189 commit e3529d3

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6 files changed

+450
-66
lines changed

6 files changed

+450
-66
lines changed

‎.github/workflows/arch_ci.yml‎

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@@ -15,7 +15,7 @@ jobs:
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DEPS_PATH: ${{ github.workspace }}/deps
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YOSYS_REVISION: bd7ee79486d4e8788f36de8c25a3fb2df451d682
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ICESTORM_REVISION: 9f66f9ce16941c6417813cb87653c735a78b53ae
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TRELLIS_REVISION: c99b22d35e4109333e7549e56cec139569a17392
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TRELLIS_REVISION: f1e5710099313d2e1862d4ef2582293f6b7ee122
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PRJOXIDE_REVISION: c3fb1526cf4a2165e15b74f4a994d153c7695fe4
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MISTRAL_REVISION: ebfc0dd2cc7d6d2159b641a397c88554840e93c9
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APYCULA_REVISION: 0.5.1a1

‎machxo2/arch.cc‎

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@@ -433,6 +433,8 @@ bool Arch::route()
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assignArchInfo();
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route_globals();
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bool result;
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if (router == "router1") {
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result = router1(getCtx(), Router1Cfg(getCtx()));

‎machxo2/arch.h‎

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@@ -967,6 +967,9 @@ struct Arch : BaseArch<ArchRanges>
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// Apply LPF constraints to the context
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bool apply_lpf(std::string filename, std::istream &in);
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// Global clock routing
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void route_globals();
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static const std::string defaultPlacer;
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static const std::vector<std::string> availablePlacers;
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static const std::string defaultRouter;

‎machxo2/bitstream.cc‎

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@@ -86,9 +86,14 @@ struct MachXO2Bitgen
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// clang-format on
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};
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if (prefix2 == "G_" || prefix2 == "L_" || prefix2 == "R_" || prefix7 == "BRANCH_")
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if (prefix2 == "G_" || prefix7 == "BRANCH_")
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return basename;
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if (prefix2 == "L_" || prefix2 == "R_") {
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if (loc.x == 0 || loc.x == (ctx->getGridDimX() - 1))
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return "G_" + basename.substr(2);
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return basename;
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}
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if (prefix2 == "U_" || prefix2 == "D_") {
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// We needded to keep U_ and D_ prefixes to generate the routing
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// graph connections properly, but in truth they are not relevant

‎machxo2/globals.cc‎

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@@ -0,0 +1,178 @@
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/*
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* nextpnr -- Next Generation Place and Route
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*
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* Copyright (C) 2020-23 gatecat <[email protected]>
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*
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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*/
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#include "log.h"
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#include "nextpnr.h"
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#include "util.h"
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#include <queue>
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NEXTPNR_NAMESPACE_BEGIN
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struct MachxoGlobalRouter
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{
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Context *ctx;
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MachxoGlobalRouter(Context *ctx) : ctx(ctx){};
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// When routing globals; we allow global->local for some tricky cases but never local->local
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bool global_pip_filter(PipId pip) const
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{
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WireId src = ctx->getPipSrcWire(pip);
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const char *s = ctx->tile_info(src)->wire_data[src.index].name.get();
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if ((s[0] == 'H' || s[0] == 'V') && s[1] == '0')
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return false;
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return true;
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}
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// Dedicated backwards BFS routing for global networks
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template <typename Tfilt>
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bool backwards_bfs_route(NetInfo *net, store_index<PortRef> user_idx, int iter_limit, bool strict, Tfilt pip_filter)
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{
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// Queue of wires to visit
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std::queue<WireId> visit;
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// Wire -> upstream pip
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dict<WireId, PipId> backtrace;
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// Lookup source and destination wires
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WireId src = ctx->getNetinfoSourceWire(net);
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WireId dst = ctx->getNetinfoSinkWire(net, net->users.at(user_idx), 0);
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if (src == WireId())
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log_error("Net '%s' has an invalid source port %s.%s\n", ctx->nameOf(net), ctx->nameOf(net->driver.cell),
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ctx->nameOf(net->driver.port));
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if (dst == WireId())
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log_error("Net '%s' has an invalid sink port %s.%s\n", ctx->nameOf(net),
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ctx->nameOf(net->users.at(user_idx).cell), ctx->nameOf(net->users.at(user_idx).port));
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if (ctx->getBoundWireNet(src) != net)
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ctx->bindWire(src, net, STRENGTH_LOCKED);
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if (src == dst) {
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// Nothing more to do
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return true;
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}
73+
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visit.push(dst);
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backtrace[dst] = PipId();
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int iter = 0;
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79+
while (!visit.empty() && (iter++ < iter_limit)) {
80+
WireId cursor = visit.front();
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visit.pop();
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// Search uphill pips
83+
for (PipId pip : ctx->getPipsUphill(cursor)) {
84+
// Skip pip if unavailable, and not because it's already used for this net
85+
if (!ctx->checkPipAvail(pip) && ctx->getBoundPipNet(pip) != net)
86+
continue;
87+
WireId prev = ctx->getPipSrcWire(pip);
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// Ditto for the upstream wire
89+
if (!ctx->checkWireAvail(prev) && ctx->getBoundWireNet(prev) != net)
90+
continue;
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// Skip already visited wires
92+
if (backtrace.count(prev))
93+
continue;
94+
// Apply our custom pip filter
95+
if (!pip_filter(pip))
96+
continue;
97+
// Add to the queue
98+
visit.push(prev);
99+
backtrace[prev] = pip;
100+
// Check if we are done yet
101+
if (prev == src)
102+
goto done;
103+
}
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if (false) {
105+
done:
106+
break;
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}
108+
}
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if (backtrace.count(src)) {
111+
WireId cursor = src;
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std::vector<PipId> pips;
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// Create a list of pips on the routed path
114+
while (true) {
115+
PipId pip = backtrace.at(cursor);
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if (pip == PipId())
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break;
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pips.push_back(pip);
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cursor = ctx->getPipDstWire(pip);
120+
}
121+
// Reverse that list
122+
std::reverse(pips.begin(), pips.end());
123+
// Bind pips until we hit already-bound routing
124+
for (PipId pip : pips) {
125+
WireId dst = ctx->getPipDstWire(pip);
126+
if (ctx->getBoundWireNet(dst) == net)
127+
break;
128+
ctx->bindPip(pip, net, STRENGTH_LOCKED);
129+
}
130+
return true;
131+
} else {
132+
if (strict)
133+
log_error("Failed to route net '%s' from %s to %s using dedicated routing.\n", ctx->nameOf(net),
134+
ctx->nameOfWire(src), ctx->nameOfWire(dst));
135+
return false;
136+
}
137+
}
138+
139+
bool is_relaxed_sink(const PortRef &sink) const
140+
{
141+
// Cases where global clocks are driving fabric
142+
if ((sink.cell->type == id_TRELLIS_COMB && sink.port != id_WCK) ||
143+
(sink.cell->type == id_TRELLIS_FF && sink.port != id_CLK))
144+
return true;
145+
return false;
146+
}
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148+
void route_clk_net(NetInfo *net)
149+
{
150+
for (auto usr : net->users.enumerate())
151+
backwards_bfs_route(net, usr.index, 1000000, true,
152+
[&](PipId pip) { return (is_relaxed_sink(usr.value) || global_pip_filter(pip)); });
153+
log_info(" routed net '%s' using global resources\n", ctx->nameOf(net));
154+
}
155+
156+
void operator()()
157+
{
158+
log_info("Routing globals...\n");
159+
for (auto &net : ctx->nets) {
160+
NetInfo *ni = net.second.get();
161+
CellInfo *drv = ni->driver.cell;
162+
if (drv == nullptr)
163+
continue;
164+
if (drv->type.in(id_DCCA, id_DCMA)) {
165+
route_clk_net(ni);
166+
continue;
167+
}
168+
}
169+
}
170+
};
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172+
void Arch::route_globals()
173+
{
174+
MachxoGlobalRouter glb_router(getCtx());
175+
glb_router();
176+
}
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NEXTPNR_NAMESPACE_END

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