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Merge pull request #757 from antmicro/lut-mapping-cache

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interchange: Add caching of site LUT mapping solution
This commit is contained in:
gatecat 2021-07-22 14:09:40 +01:00 committed by GitHub
commit 5212e38512
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8 changed files with 511 additions and 75 deletions
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11
fpga_interchange/arch.cc
View File

@ -814,6 +814,14 @@ bool Arch::place()
getCtx()->attrs[getCtx()->id("step")] = std::string("place");
archInfoToAttributes();
// Print site LUT mapping caching stats
if (!getCtx()->arch_args.disable_lut_mapping_cache) {
log_info("Site LUT mapping cache stats:\n");
log_info(" miss ratio: %.1f%%\n", getCtx()->site_lut_mapping_cache.getMissRatio() * 100.0f);
log_info(" peak size : %zuMB (%zu items)\n", getCtx()->site_lut_mapping_cache.getSizeMB(),
getCtx()->site_lut_mapping_cache.getCount());
}
getCtx()->check();
return true;
@ -837,6 +845,9 @@ static void prepare_sites_for_routing(Context *ctx)
// pins to ensure a routeable pin choice.
ctx->site_routing_cache.clear();
// Clear the LUT mapping cache
ctx->site_lut_mapping_cache.clear();
// Have site router bind site routing (via bindPip and bindWire).
// This is important so that the pseudo pips are correctly blocked prior
// to handing the design to the generalized router algorithms.

3
fpga_interchange/arch.h
View File

@ -39,6 +39,7 @@
#include "dedicated_interconnect.h"
#include "lookahead.h"
#include "pseudo_pip_model.h"
#include "site_lut_mapping_cache.h"
#include "site_router.h"
#include "site_routing_cache.h"
@ -50,6 +51,7 @@ struct ArchArgs
std::string package;
bool rebuild_lookahead;
bool dont_write_lookahead;
bool disable_lut_mapping_cache;
};
struct ArchRanges
@ -1133,6 +1135,7 @@ struct Arch : ArchAPI<ArchRanges>
Lookahead lookahead;
mutable RouteNodeStorage node_storage;
mutable SiteRoutingCache site_routing_cache;
mutable SiteLutMappingCache site_lut_mapping_cache;
bool disallow_site_routing;
CellParameters cell_parameters;

92
fpga_interchange/luts.cc
View File

@ -22,6 +22,8 @@
#include "log.h"
#include "nextpnr.h"
#include "site_lut_mapping_cache.h"
//#define DEBUG_LUT_ROTATION
NEXTPNR_NAMESPACE_BEGIN
@ -253,7 +255,8 @@ uint32_t LutMapper::check_wires(const std::vector<std::vector<int32_t>> &bel_to_
return vcc_mask;
}
bool LutMapper::remap_luts(const Context *ctx, pool<const LutBel *, hash_ptr_ops> *blocked_luts)
bool LutMapper::remap_luts(const Context *ctx, SiteLutMappingResult *lut_mapping,
pool<const LutBel *, hash_ptr_ops> *blocked_luts)
{
dict<NetInfo *, LutPin, hash_ptr_ops> lut_pin_map;
std::vector<const LutBel *> lut_bels;
@ -377,32 +380,9 @@ bool LutMapper::remap_luts(const Context *ctx, pool<const LutBel *, hash_ptr_ops
}
}
// Push new cell -> BEL pin maps out to cells now that equations have been
// verified!
for (size_t cell_idx = 0; cell_idx < cells.size(); ++cell_idx) {
CellInfo *cell = cells[cell_idx];
auto &lut_bel = *lut_bels[cell_idx];
for (size_t pin_idx = 0; pin_idx < cell->lut_cell.pins.size(); ++pin_idx) {
auto &bel_pins = cell->cell_bel_pins[cell->lut_cell.pins[pin_idx]];
bel_pins.clear();
bel_pins.push_back(lut_bel.pins[cell_to_bel_pin_remaps[cell_idx][pin_idx]]);
}
}
if (cells.size() == element.lut_bels.size()) {
for (size_t cell_idx = 0; cell_idx < cells.size(); ++cell_idx) {
CellInfo *cell = cells[cell_idx];
auto &lut_bel = *lut_bels[cell_idx];
cell->lut_cell.vcc_pins.clear();
for (size_t bel_pin_idx = 0; bel_pin_idx < lut_bel.pins.size(); ++bel_pin_idx) {
if ((used_pins & (1 << bel_pin_idx)) == 0) {
NPNR_ASSERT(bel_to_cell_pin_remaps[cell_idx][bel_pin_idx] == -1);
cell->lut_cell.vcc_pins.emplace(lut_bel.pins.at(bel_pin_idx));
}
}
}
} else {
// Not all LUT inputs are used
uint32_t vcc_pins = 0;
if (cells.size() != element.lut_bels.size()) {
// Look to see if wires can be run from element inputs to unused
// outputs. If not, block the BEL pin by tying to VCC.
//
@ -411,7 +391,7 @@ bool LutMapper::remap_luts(const Context *ctx, pool<const LutBel *, hash_ptr_ops
//
// Use Arch::prefered_constant_net_type to determine what
// constant net should be used for unused pins.
uint32_t vcc_pins = check_wires(bel_to_cell_pin_remaps, lut_bels, used_pins, blocked_luts);
vcc_pins = check_wires(bel_to_cell_pin_remaps, lut_bels, used_pins, blocked_luts);
#if defined(DEBUG_LUT_ROTATION)
log_info("vcc_pins = 0x%x", vcc_pins);
for (size_t cell_idx = 0; cell_idx < cells.size(); ++cell_idx) {
@ -420,34 +400,52 @@ bool LutMapper::remap_luts(const Context *ctx, pool<const LutBel *, hash_ptr_ops
}
log("\n");
#endif
}
// Fill in the LUT mapping result
// Push new cell -> BEL pin maps out to cells now that equations have been
// verified!
lut_mapping->cells.reserve(cells.size());
for (size_t cell_idx = 0; cell_idx < cells.size(); ++cell_idx) {
CellInfo *cell = cells[cell_idx];
auto &lut_bel = *lut_bels[cell_idx];
cell->lut_cell.vcc_pins.clear();
for (size_t bel_pin_idx = 0; bel_pin_idx < lut_bel.pins.size(); ++bel_pin_idx) {
CellInfo *cellInfo = cells[cell_idx];
auto &lutBel = *lut_bels[cell_idx];
// Add the cell data
SiteLutMappingResult::Cell cell;
cell.belIndex = cellInfo->bel.index;
// Cell to BEL pin map
for (size_t pin_idx = 0; pin_idx < cellInfo->lut_cell.pins.size(); ++pin_idx) {
IdString cellPin = cellInfo->lut_cell.pins[pin_idx];
IdString belPin = lutBel.pins[cell_to_bel_pin_remaps[cell_idx][pin_idx]];
cell.belPins[cellPin] = belPin;
}
cell.lutCell.vcc_pins.clear();
// All LUT inputs used
if (cells.size() == element.lut_bels.size()) {
for (size_t bel_pin_idx = 0; bel_pin_idx < lutBel.pins.size(); ++bel_pin_idx) {
if ((used_pins & (1 << bel_pin_idx)) == 0) {
NPNR_ASSERT(bel_to_cell_pin_remaps[cell_idx][bel_pin_idx] == -1);
cell.lutCell.vcc_pins.emplace(lutBel.pins.at(bel_pin_idx));
}
}
}
// Only some LUT inputs used
else {
for (size_t bel_pin_idx = 0; bel_pin_idx < lutBel.pins.size(); ++bel_pin_idx) {
if ((vcc_pins & (1 << bel_pin_idx)) != 0) {
NPNR_ASSERT(bel_to_cell_pin_remaps[cell_idx][bel_pin_idx] == -1);
auto pin = lut_bel.pins.at(bel_pin_idx);
cell->lut_cell.vcc_pins.emplace(pin);
}
auto pin = lutBel.pins.at(bel_pin_idx);
cell.lutCell.vcc_pins.emplace(pin);
}
}
}
#ifdef DEBUG_LUT_ROTATION
log_info("Final mapping:\n");
for (size_t cell_idx = 0; cell_idx < cells.size(); ++cell_idx) {
CellInfo *cell = cells[cell_idx];
for (auto &cell_pin_pair : cell->cell_bel_pins) {
log_info("%s %s %s =>", cell->type.c_str(ctx), cell->name.c_str(ctx), cell_pin_pair.first.c_str(ctx));
for (auto bel_pin : cell_pin_pair.second) {
log(" %s", bel_pin.c_str(ctx));
lut_mapping->cells.push_back(cell);
}
log("\n");
}
}
#endif
return true;
}

13
fpga_interchange/luts.h
View File

@ -31,6 +31,8 @@ NEXTPNR_NAMESPACE_BEGIN
struct CellInfo;
struct Context;
struct SiteLutMappingResult;
enum LogicLevel
{
LL_Zero,
@ -66,6 +68,14 @@ struct LutBel
int32_t max_pin;
};
struct SiteLutMapping
{
struct LutCellMapping
{
LutCell lut_cell;
};
};
// Work forward from cell definition and cell -> bel pin map and check that
// equation is valid.
void check_equation(const LutCell &lut_cell, const dict<IdString, IdString> &cell_to_bel_map, const LutBel &lut_bel,
@ -89,7 +99,8 @@ struct LutMapper
std::vector<CellInfo *> cells;
bool remap_luts(const Context *ctx, pool<const LutBel *, hash_ptr_ops> *blocked_luts);
bool remap_luts(const Context *ctx, SiteLutMappingResult *lut_mapping,
pool<const LutBel *, hash_ptr_ops> *blocked_luts);
// Determine which wires given the current mapping must be tied to the
// default constant.

2
fpga_interchange/main.cc
View File

@ -57,6 +57,7 @@ po::options_description FpgaInterchangeCommandHandler::getArchOptions()
specific.add_options()("package", po::value<std::string>(), "Package to use");
specific.add_options()("rebuild-lookahead", "Ignore lookahead cache and rebuild");
specific.add_options()("dont-write-lookahead", "Don't write the lookahead file");
specific.add_options()("disable-lut-mapping-cache", "Disable caching of LUT mapping solutions in site router");
return specific;
}
@ -76,6 +77,7 @@ std::unique_ptr<Context> FpgaInterchangeCommandHandler::createContext(dict<std::
ArchArgs chipArgs;
chipArgs.rebuild_lookahead = vm.count("rebuild_lookahead") != 0;
chipArgs.dont_write_lookahead = vm.count("dont_write_lookahead") != 0;
chipArgs.disable_lut_mapping_cache = vm.count("disable-lut-mapping-cache") != 0;
if (!vm.count("chipdb")) {
log_error("chip database binary must be provided\n");

196
fpga_interchange/site_lut_mapping_cache.cc Normal file
View File

@ -0,0 +1,196 @@
/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2021 Symbiflow Authors
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "site_lut_mapping_cache.h"
#include "nextpnr.h"
NEXTPNR_NAMESPACE_BEGIN
// ============================================================================
SiteLutMappingKey SiteLutMappingKey::create(const SiteInformation &siteInfo)
{
const Context *ctx = siteInfo.ctx;
// Look for LUT cells in the site
std::vector<CellInfo *> lutCells;
lutCells.reserve(siteInfo.cells_in_site.size());
for (CellInfo *cellInfo : siteInfo.cells_in_site) {
// Not a LUT cell
if (cellInfo->lut_cell.pins.empty()) {
continue;
}
// Not bound to a LUT BEL
BelId bel = cellInfo->bel;
const auto &bel_data = bel_info(ctx->chip_info, bel);
if (bel_data.lut_element == -1) {
continue;
}
lutCells.push_back(cellInfo);
}
// Sort cells by BEL indices to maintain always the same order
std::sort(lutCells.begin(), lutCells.end(),
[](const CellInfo *a, const CellInfo *b) { return a->bel.index > b->bel.index; });
// Initialize the key
SiteLutMappingKey key;
key.tileType = siteInfo.tile_type;
key.siteType = ctx->chip_info->sites[siteInfo.site].site_type;
key.numCells = 0;
// Get bound nets. Store localized (to the LUT cluster) net indices only
// to get always the same key for the same LUT port configuration even
// when the actual global net names are different.
dict<IdString, int32_t> netMap;
for (CellInfo *cellInfo : lutCells) {
NPNR_ASSERT(key.numCells < SiteLutMappingKey::MAX_LUT_CELLS);
auto &cell = key.cells[key.numCells++];
cell.type = cellInfo->type;
cell.belIndex = cellInfo->bel.index;
cell.conns.fill(0);
size_t portId = 0;
for (const auto &port : cellInfo->ports) {
const auto &portInfo = port.second;
// Consider only LUT inputs
if (portInfo.type != PORT_IN) {
continue;
}
// Assign net id if any
int32_t netId = 0;
if (portInfo.net != nullptr) {
auto netInfo = portInfo.net;
auto it = netMap.find(netInfo->name);
if (it != netMap.end()) {
netId = it->second;
} else {
netId = (int32_t)netMap.size() + 1;
netMap[netInfo->name] = netId;
}
}
NPNR_ASSERT(portId < SiteLutMappingKey::MAX_LUT_INPUTS);
cell.conns[portId++] = netId;
}
}
// Compute hash
key.computeHash();
return key;
}
// ============================================================================
bool SiteLutMappingResult::apply(const SiteInformation &siteInfo)
{
Context *ctx = const_cast<Context *>(siteInfo.ctx);
TileStatus &tileStatus = ctx->get_tile_status(siteInfo.tile);
for (auto &cell : cells) {
// Get the bound cell
CellInfo *cellInfo = tileStatus.boundcells[cell.belIndex];
NPNR_ASSERT(cellInfo);
// Double check BEL binding
NPNR_ASSERT(cellInfo->bel.tile == siteInfo.tile);
NPNR_ASSERT(cellInfo->bel.index == cell.belIndex);
// Cell <-> BEL pin map
size_t numPins = cellInfo->lut_cell.pins.size();
for (size_t pinIdx = 0; pinIdx < numPins; ++pinIdx) {
const IdString &cellPin = cellInfo->lut_cell.pins[pinIdx];
auto &belPins = cellInfo->cell_bel_pins[cellPin];
// There is only one pin
belPins.resize(1);
belPins[0] = cell.belPins[cellPin];
}
// LUT data
// FIXME: Is there any other info that is being updated than vcc_pins ?
cellInfo->lut_cell.vcc_pins = std::move(cell.lutCell.vcc_pins);
}
return true;
}
size_t SiteLutMappingResult::getSizeInBytes() const
{
size_t size = 0;
size += sizeof(SiteLutMappingResult);
size += blockedWires.size() * sizeof(std::pair<IdString, IdString>);
for (const auto &cell : cells) {
size += sizeof(Cell);
size += cell.belPins.size() * sizeof(decltype(cell.belPins)::value_type);
}
return size;
}
// ============================================================================
void SiteLutMappingCache::add(const SiteLutMappingKey &key, const SiteLutMappingResult &result)
{
cache_[key] = result;
}
bool SiteLutMappingCache::get(const SiteLutMappingKey &key, SiteLutMappingResult *result)
{
if (cache_.count(key) == 0) {
numMisses++;
return false;
}
numHits++;
*result = cache_[key];
return true;
}
void SiteLutMappingCache::clear()
{
cache_.clear();
clearStats();
}
void SiteLutMappingCache::clearStats()
{
numHits = 0;
numMisses = 0;
}
// ============================================================================
NEXTPNR_NAMESPACE_END

185
fpga_interchange/site_lut_mapping_cache.h Normal file
View File

@ -0,0 +1,185 @@
/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2021 Symbiflow Authors
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#ifndef SITE_LUT_MAPPING_CACHE_H
#define SITE_LUT_MAPPING_CACHE_H
#include "idstring.h"
#include "nextpnr_namespaces.h"
#include "site_arch.h"
NEXTPNR_NAMESPACE_BEGIN
// Key structure used in site LUT mapping cache
struct SiteLutMappingKey
{
// Maximum number of LUT cells per site
static constexpr size_t MAX_LUT_CELLS = 8;
// Maximum number of LUT inputs per cell
static constexpr size_t MAX_LUT_INPUTS = 6;
// LUT Cell data
struct Cell
{
IdString type; // Cell type
int32_t belIndex; // Bound BEL index
// Port to net assignments. These are local net ids generated during
// key creation. This is to abstract connections from actual design
// net names. the Id 0 means unconnected.
std::array<int32_t, MAX_LUT_INPUTS> conns;
bool operator==(const Cell &other) const
{
return (type == other.type) && (belIndex == other.belIndex) && (conns == other.conns);
}
bool operator!=(const Cell &other) const
{
return (type != other.type) || (belIndex != other.belIndex) || (conns != other.conns);
}
};
int32_t tileType; // Tile type
int32_t siteType; // Site type in that tile type
size_t numCells; // LUT cell count
std::array<Cell, MAX_LUT_CELLS> cells; // LUT cell data
unsigned int hash_; // Precomputed hash
// Creates a key from the given site state
static SiteLutMappingKey create(const SiteInformation &siteInfo);
// Returns size in bytes of the key
size_t getSizeInBytes() const { return sizeof(SiteLutMappingKey); }
// Precomputes hash of the key and stores it within
void computeHash()
{
hash_ = mkhash(0, tileType);
hash_ = mkhash(hash_, siteType);
hash_ = mkhash(hash_, numCells);
for (size_t j = 0; j < numCells; ++j) {
const auto &cell = cells[j];
hash_ = mkhash(hash_, cell.type.index);
hash_ = mkhash(hash_, cell.belIndex);
for (size_t i = 0; i < MAX_LUT_INPUTS; ++i) {
hash_ = mkhash(hash_, cell.conns[i]);
}
}
}
// Compares cell data of this and other key
bool compareCells(const SiteLutMappingKey &other) const
{
if (numCells != other.numCells) {
return false;
}
for (size_t i = 0; i < numCells; ++i) {
if (cells[i] != other.cells[i]) {
return false;
}
}
return true;
}
bool operator==(const SiteLutMappingKey &other) const
{
return (hash_ == other.hash_) && (tileType == other.tileType) && (siteType == other.siteType) &&
compareCells(other);
}
bool operator!=(const SiteLutMappingKey &other) const
{
return (hash_ != other.hash_) || (tileType != other.tileType) || (siteType != other.siteType) ||
!compareCells(other);
}
unsigned int hash() const { return hash_; }
};
// Site LUT mapping result data
struct SiteLutMappingResult
{
// LUT cell data
struct Cell
{
int32_t belIndex; // BEL in tile index
LutCell lutCell; // LUT mapping data
dict<IdString, IdString> belPins; // Cell to BEL pin mapping
};
bool isValid; // Validity flag
std::vector<Cell> cells; // Cell data
pool<std::pair<IdString, IdString>> blockedWires; // Set of blocked wires
// Applies the mapping result to the site
bool apply(const SiteInformation &siteInfo);
// Returns size in bytes
size_t getSizeInBytes() const;
};
// Site LUT mapping cache object
class SiteLutMappingCache
{
public:
// Adds an entry to the cache
void add(const SiteLutMappingKey &key, const SiteLutMappingResult &result);
// Retrieves an entry from the cache. Returns false if not found
bool get(const SiteLutMappingKey &key, SiteLutMappingResult *result);
// Clears the cache
void clear();
// Clears statistics counters of the cache
void clearStats();
// Return get() miss ratio
float getMissRatio() const { return (float)numMisses / (float)(numHits + numMisses); }
// Returns count of entries in the cache
size_t getCount() const { return cache_.size(); }
// Returns size of the cache rounded upwards to full MBs.
size_t getSizeMB() const
{
size_t size = 0;
for (const auto &it : cache_) {
size += it.first.getSizeInBytes();
size += it.second.getSizeInBytes();
}
const size_t MB = 1024L * 1024L;
return (size + MB - 1) / MB; // Round up to megabytes
}
private:
dict<SiteLutMappingKey, SiteLutMappingResult> cache_; // The cache
size_t numHits = 0; // Hit count
size_t numMisses = 0; // Miss count
};
NEXTPNR_NAMESPACE_END
#endif /* SITE_LUT_MAPPING_CACHE_H */

40
fpga_interchange/site_router.cc
View File

@ -1050,6 +1050,15 @@ static void apply_routing(Context *ctx, const SiteArch &site_arch, pool<std::pai
static bool map_luts_in_site(const SiteInformation &site_info, pool<std::pair<IdString, IdString>> *blocked_wires)
{
const Context *ctx = site_info.ctx;
bool enable_cache = !ctx->arch_args.disable_lut_mapping_cache;
// Create a site LUT mapping key
SiteLutMappingKey key = SiteLutMappingKey::create(site_info);
// Get the solution from cache. If not found then compute it
SiteLutMappingResult lutMapping;
if (!enable_cache || !ctx->site_lut_mapping_cache.get(key, &lutMapping)) {
const std::vector<LutElement> &lut_elements = ctx->lut_elements.at(site_info.tile_type);
std::vector<LutMapper> lut_mappers;
lut_mappers.reserve(lut_elements.size());
@ -1069,23 +1078,43 @@ static bool map_luts_in_site(const SiteInformation &site_info, pool<std::pair<Id
}
}
blocked_wires->clear();
bool res = true;
lutMapping.blockedWires.clear();
for (LutMapper lut_mapper : lut_mappers) {
if (lut_mapper.cells.empty()) {
continue;
}
pool<const LutBel *, hash_ptr_ops> blocked_luts;
if (!lut_mapper.remap_luts(ctx, &blocked_luts)) {
return false;
if (!lut_mapper.remap_luts(ctx, &lutMapping, &blocked_luts)) {
res = false;
break;
}
for (const LutBel *lut_bel : blocked_luts) {
blocked_wires->emplace(std::make_pair(lut_bel->name, lut_bel->output_pin));
lutMapping.blockedWires.emplace(std::make_pair(lut_bel->name, lut_bel->output_pin));
}
}
return true;
lutMapping.isValid = res;
// Add the solution to the cache
if (enable_cache) {
ctx->site_lut_mapping_cache.add(key, lutMapping);
}
}
// Apply the solution if valid
if (lutMapping.isValid) {
lutMapping.apply(site_info);
blocked_wires->clear();
blocked_wires->insert(lutMapping.blockedWires.begin(), lutMapping.blockedWires.end());
}
return lutMapping.isValid;
}
// Block outputs of unavailable LUTs to prevent site router from using them.
@ -1255,6 +1284,7 @@ bool SiteRouter::checkSiteRouting(const Context *ctx, const TileStatus &tile_sta
// Because site routing checks are expensive, cache them.
// SiteRouter::bindBel/unbindBel should correctly invalid the cache by
// setting dirty=true.
if (!dirty) {
return site_ok;
}