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Clean up muxpack

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This commit is contained in:
Akash Levy 2025-02-14 06:56:12 -08:00
parent 0f5f9ae28c
commit db83aaee09
1 changed files with 33 additions and 69 deletions
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102
passes/opt/muxpack.cc
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@ -135,26 +135,6 @@ struct MuxpackWorker
pool<Cell*> candidate_cells; pool<Cell*> candidate_cells;
ExclusiveDatabase excl_db; ExclusiveDatabase excl_db;
// Splitfanout limit
int limit = -1;
bool fanout_in_range(SigSpec outsig)
{
// Check if output signal is "bit-split", skip if so
// This is a lookahead for the splitfanout pass that has this limitation
auto bit_users = bit_users_db[outsig[0]];
for (int i = 0; i < GetSize(outsig); i++) {
if (bit_users_db[outsig[i]] != bit_users) {
return false;
}
}
// Skip if fanout is above limit
if (limit != -1 && GetSize(bit_users) > limit) {
return false;
}
return true;
}
void make_sig_chain_next_prev() void make_sig_chain_next_prev()
{ {
@ -180,10 +160,8 @@ struct MuxpackWorker
for (auto a_bit : a_sig) for (auto a_bit : a_sig)
sigbit_with_non_chain_users.insert(a_bit); sigbit_with_non_chain_users.insert(a_bit);
else { else {
if (fanout_in_range(y_sig)) { sig_chain_next[a_sig] = cell;
sig_chain_next[a_sig] = cell; candidate_cells.insert(cell);
candidate_cells.insert(cell);
}
} }
if (!b_sig.empty()) { if (!b_sig.empty()) {
@ -191,18 +169,12 @@ struct MuxpackWorker
for (auto b_bit : b_sig) for (auto b_bit : b_sig)
sigbit_with_non_chain_users.insert(b_bit); sigbit_with_non_chain_users.insert(b_bit);
else { else {
if (fanout_in_range(y_sig)) { sig_chain_next[b_sig] = cell;
sig_chain_next[b_sig] = cell; candidate_cells.insert(cell);
candidate_cells.insert(cell);
}
} }
} }
if (fanout_in_range(y_sig)) { sig_chain_prev[y_sig] = cell;
// Mark cell as the previous in the chain relative to y_sig
sig_chain_prev[y_sig] = cell;
}
continue; continue;
} }
@ -323,26 +295,26 @@ struct MuxpackWorker
} }
if (make_excl) { if (make_excl) {
/* We create the following one-hot select line decoder /* Create the following one-hot select line decoder:
S0 S1 S2 S3 ... S0 S1 S2 S3 ...
| | | | | | | |
+--------+ +----------+ +-------------+ | +--------+ +----------+ +-------------+ |
| _|_ | _|_ | _|_ | | _|_ | _|_ | _|_ |
| \_/ | \_/ | \_/ | | \_/ | \_/ | \_/ |
| o | o | o | | o | o | o |
| | | | | ___ | | | | | | | ___ | |
| +----------+ | | / | | | | +----------+ | | / | | |
| | | |___| | / |___| | | | | |___| | / |___| |
| |___| | & | / / | & | / ... | |___| | & | / / | & | / ...
| | & | \___/ / / \___/ / / | | & | \___/ / / \___/ / /
| \___/ | | / | | / | \___/ | | / | | /
| | +------+ +-------+ | | +------+ +-------+
| | | | | | | | | | | |
| | |___| |___| | | |___| |___|
| | | & | | & | | | | & | | & |
| | \___/ \___/ | | \___/ \___/
| | | | | | | |
S0 S0'S1 S0'S1'S2 S0'S1'S2'S3 ... S0 S0'S1 S0'S1'S2 S0'S1'S2'S3 ...
*/ */
SigSpec decodedSelect; SigSpec decodedSelect;
Cell *cell = last_cell; Cell *cell = last_cell;
@ -389,11 +361,10 @@ struct MuxpackWorker
} }
} }
void cleanup(bool remove_cell) void cleanup()
{ {
if (remove_cell) for (auto cell : remove_cells)
for (auto cell : remove_cells) module->remove(cell);
module->remove(cell);
remove_cells.clear(); remove_cells.clear();
sig_chain_next.clear(); sig_chain_next.clear();
@ -402,8 +373,8 @@ struct MuxpackWorker
candidate_cells.clear(); candidate_cells.clear();
} }
MuxpackWorker(Design *design, Module *module, bool assume_excl, bool make_excl, int limit) MuxpackWorker(Module *module, bool assume_excl, bool make_excl) :
: module(module), sigmap(module), mux_count(0), pmux_count(0), excl_db(module, sigmap, assume_excl, make_excl), limit(limit) module(module), sigmap(module), mux_count(0), pmux_count(0), excl_db(module, sigmap, assume_excl, make_excl)
{ {
// Build bit_drivers_db // Build bit_drivers_db
@ -459,7 +430,7 @@ struct MuxpackWorker
process_chain(chain, make_excl); process_chain(chain, make_excl);
} }
// Clean up // Clean up
cleanup(true); cleanup();
} }
}; };
@ -479,11 +450,9 @@ struct MuxpackPass : public Pass {
log("whose select lines are driven by '$eq' cells with other such cells if it can be\n"); log("whose select lines are driven by '$eq' cells with other such cells if it can be\n");
log("certain that their select inputs are mutually exclusive.\n"); log("certain that their select inputs are mutually exclusive.\n");
log("\n"); log("\n");
log(" -fanout_limit n\n");
log(" max fanout to split.\n");
log("\n");
log(" -assume_excl\n"); log(" -assume_excl\n");
log(" assume mutually exclusive constraint when packing (may result in inequivalence)\n"); log(" assume mutually exclusive constraint when packing (may result in inequivalence)\n");
log("\n");
log(" -make_excl\n"); log(" -make_excl\n");
log(" Adds a one-hot decoder on the control signals\n"); log(" Adds a one-hot decoder on the control signals\n");
log("\n"); log("\n");
@ -492,17 +461,12 @@ struct MuxpackPass : public Pass {
{ {
bool assume_excl = false; bool assume_excl = false;
bool make_excl = false; bool make_excl = false;
int limit = -1;
log_header(design, "Executing MUXPACK pass ($mux cell cascades to $pmux).\n"); log_header(design, "Executing MUXPACK pass ($mux cell cascades to $pmux).\n");
size_t argidx; size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++) for (argidx = 1; argidx < args.size(); argidx++)
{ {
if (args[argidx] == "-fanout_limit" && argidx + 1 < args.size()) {
limit = std::stoi(args[++argidx]);
continue;
}
if (args[argidx] == "-assume_excl") { if (args[argidx] == "-assume_excl") {
assume_excl = true; assume_excl = true;
continue; continue;
@ -520,7 +484,7 @@ struct MuxpackPass : public Pass {
int pmux_count = 0; int pmux_count = 0;
for (auto module : design->selected_modules()) { for (auto module : design->selected_modules()) {
MuxpackWorker worker(design, module, assume_excl, make_excl, limit); MuxpackWorker worker(module, assume_excl, make_excl);
mux_count += worker.mux_count; mux_count += worker.mux_count;
pmux_count += worker.pmux_count; pmux_count += worker.pmux_count;
} }