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ecp5: Improve packing density

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Signed-off-by: David Shah <dave@ds0.me>
This commit is contained in:
David Shah 2019-02-25 11:07:21 +00:00
parent a0fa164399
commit 95a85c8ea7
2 changed files with 59 additions and 1 deletions
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2
ecp5/arch.cc
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@ -457,7 +457,7 @@ delay_t Arch::estimateDelay(WireId src, WireId dst) const
int dx = abs(src_loc.first - dst_loc.first), dy = abs(src_loc.second - dst_loc.second);
return (130 - 25 * args.speed) *
(8 + std::max(dx - 5, 0) + std::max(dy - 5, 0) + 2 * (std::min(dx, 5) + std::min(dy, 5)));
(6 + std::max(dx - 5, 0) + std::max(dy - 5, 0) + 2 * (std::min(dx, 5) + std::min(dy, 5)));
}
delay_t Arch::predictDelay(const NetInfo *net_info, const PortRef &sink) const

58
ecp5/pack.cc
View File

@ -165,6 +165,7 @@ class Ecp5Packer
CellInfo *ci = cell.second;
if (is_lut(ctx, ci) && procdLuts.find(cell.first) == procdLuts.end()) {
NetInfo *znet = ci->ports.at(ctx->id("Z")).net;
std::vector<NetInfo *> inpnets;
if (znet != nullptr) {
for (auto user : znet->users) {
if (is_lut(ctx, user.cell) && user.cell != ci &&
@ -229,14 +230,71 @@ class Ecp5Packer
}
}
}
// Pack LUTs feeding the same CCU2, RAM or DFF into a SLICE
if (znet != nullptr && znet->users.size() < 10) {
for (auto user : znet->users) {
if (is_lc(ctx, user.cell) || user.cell->type == ctx->id("DP16KD") || is_ff(ctx, user.cell)) {
for (auto port : user.cell->ports) {
if (port.second.type != PORT_IN || port.second.net == nullptr || port.second.net == znet)
continue;
if (port.second.net->users.size() > 10)
continue;
CellInfo *drv = port.second.net->driver.cell;
if (drv == nullptr)
continue;
if (is_lut(ctx, drv) && !procdLuts.count(drv->name) && can_pack_lutff(ci->name, drv->name)) {
procdLuts.insert(ci->name);
procdLuts.insert(drv->name);
lutPairs[ci->name] = drv->name;
goto paired_inlut;
}
}
}
}
}
// Pack LUTs sharing an input with a simple fanout-based heuristic
for (const char *inp : {"A", "B", "C", "D"}) {
NetInfo *innet = ci->ports.at(ctx->id(inp)).net;
if (innet != nullptr && innet->users.size() < 5 && innet->users.size() > 1)
inpnets.push_back(innet);
}
std::sort(inpnets.begin(), inpnets.end(), [&](const NetInfo *a, const NetInfo *b) {
return a->users.size() < b->users.size();
});
for (auto inet : inpnets) {
for (auto &user : inet->users) {
if (user.cell == nullptr || user.cell == ci || !is_lut(ctx, user.cell))
continue;
if (procdLuts.count(user.cell->name))
continue;
if (can_pack_lutff(ci->name, user.cell->name)) {
procdLuts.insert(ci->name);
procdLuts.insert(user.cell->name);
lutPairs[ci->name] = user.cell->name;
goto paired_inlut;
}
}
}
if (false) {
paired_inlut:
continue;
}
}
}
if (ctx->debug) {
log_info("Singleton LUTs (packer QoR debug): \n");
for (auto cell : sorted(ctx->cells))
if (is_lut(ctx, cell.second) && !procdLuts.count(cell.first))
log_info(" %s\n", cell.first.c_str(ctx));
}
}
// Return true if an port is a top level port that provides its own IOBUF
bool is_top_port(PortRef &port)
{