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Cleanups and improvements in wreduce pass

This commit is contained in:
Clifford Wolf 2014-08-05 13:11:04 +02:00
parent 1c182cedb7
commit d3b1a29708
1 changed files with 79 additions and 49 deletions
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128
passes/cmds/wreduce.cc
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@ -61,8 +61,10 @@ struct WreduceWorker
WreduceWorker(WreduceConfig *config, Module *module) : WreduceWorker(WreduceConfig *config, Module *module) :
config(config), module(module), mi(module) { } config(config), module(module), mi(module) { }
void run_cell_mux(Cell *cell) bool run_cell_mux(Cell *cell)
{ {
// Reduce size of MUX if inputs agree on a value for a bit or a output bit is unused
SigSpec sig_a = mi.sigmap(cell->getPort("\\A")); SigSpec sig_a = mi.sigmap(cell->getPort("\\A"));
SigSpec sig_b = mi.sigmap(cell->getPort("\\B")); SigSpec sig_b = mi.sigmap(cell->getPort("\\B"));
SigSpec sig_s = mi.sigmap(cell->getPort("\\S")); SigSpec sig_s = mi.sigmap(cell->getPort("\\S"));
@ -90,49 +92,60 @@ struct WreduceWorker
bits_removed.push_back(ref); bits_removed.push_back(ref);
} }
if (!bits_removed.empty()) if (bits_removed.empty())
{ return false;
SigSpec sig_removed;
for (int i = SIZE(bits_removed)-1; i >= 0; i--)
sig_removed.append_bit(bits_removed[i]);
log("Removed top %d bits (of %d) from mux cell %s.%s (%s).\n", SigSpec sig_removed;
SIZE(sig_removed), SIZE(sig_y), log_id(module), log_id(cell), log_id(cell->type)); for (int i = SIZE(bits_removed)-1; i >= 0; i--)
sig_removed.append_bit(bits_removed[i]);
int n_removed = SIZE(sig_removed); log("Removed top %d bits (of %d) from mux cell %s.%s (%s).\n",
int n_kept = SIZE(sig_y) - SIZE(sig_removed); SIZE(sig_removed), SIZE(sig_y), log_id(module), log_id(cell), log_id(cell->type));
SigSpec new_work_queue_bits; int n_removed = SIZE(sig_removed);
new_work_queue_bits.append(sig_a.extract(n_kept, n_removed)); int n_kept = SIZE(sig_y) - SIZE(sig_removed);
new_work_queue_bits.append(sig_y.extract(n_kept, n_removed));
SigSpec new_sig_a = sig_a.extract(0, n_kept); SigSpec new_work_queue_bits;
SigSpec new_sig_y = sig_y.extract(0, n_kept); new_work_queue_bits.append(sig_a.extract(n_kept, n_removed));
SigSpec new_sig_b; new_work_queue_bits.append(sig_y.extract(n_kept, n_removed));
for (int k = 0; k < SIZE(sig_s); k++) { SigSpec new_sig_a = sig_a.extract(0, n_kept);
new_sig_b.append(sig_b.extract(k*SIZE(sig_a), n_kept)); SigSpec new_sig_y = sig_y.extract(0, n_kept);
new_work_queue_bits.append(sig_b.extract(k*SIZE(sig_a) + n_kept, n_removed)); SigSpec new_sig_b;
}
for (auto bit : new_work_queue_bits) for (int k = 0; k < SIZE(sig_s); k++) {
work_queue_bits.insert(bit); new_sig_b.append(sig_b.extract(k*SIZE(sig_a), n_kept));
new_work_queue_bits.append(sig_b.extract(k*SIZE(sig_a) + n_kept, n_removed));
cell->setPort("\\A", new_sig_a);
cell->setPort("\\B", new_sig_b);
cell->setPort("\\Y", new_sig_y);
cell->fixup_parameters();
module->connect(sig_y.extract(n_kept, n_removed), sig_removed);
} }
for (auto bit : new_work_queue_bits)
work_queue_bits.insert(bit);
cell->setPort("\\A", new_sig_a);
cell->setPort("\\B", new_sig_b);
cell->setPort("\\Y", new_sig_y);
cell->fixup_parameters();
module->connect(sig_y.extract(n_kept, n_removed), sig_removed);
return true;
} }
void run_reduce_inport(Cell *cell, char port) bool run_reduce_inport(Cell *cell, char port, int max_port_size)
{ {
bool is_signed = cell->getParam(stringf("\\%c_SIGNED", port)).as_bool(); bool is_signed = cell->getParam(stringf("\\%c_SIGNED", port)).as_bool();
SigSpec sig = mi.sigmap(cell->getPort(stringf("\\%c", port))); SigSpec sig = mi.sigmap(cell->getPort(stringf("\\%c", port)));
if (port == 'B' && cell->type.in("$shl", "$shr", "$sshl", "$sshr"))
is_signed = false;
int bits_removed = 0; int bits_removed = 0;
if (SIZE(sig) > max_port_size) {
bits_removed = SIZE(sig) - max_port_size;
for (auto bit : sig.extract(max_port_size, bits_removed))
work_queue_bits.insert(bit);
sig = sig.extract(0, max_port_size);
}
if (is_signed) { if (is_signed) {
while (SIZE(sig) > 1 && constmap(sig[SIZE(sig)-1]) == constmap(sig[SIZE(sig)-2])) while (SIZE(sig) > 1 && constmap(sig[SIZE(sig)-1]) == constmap(sig[SIZE(sig)-2]))
work_queue_bits.insert(sig[SIZE(sig)-1]), sig.remove(SIZE(sig)-1), bits_removed++; work_queue_bits.insert(sig[SIZE(sig)-1]), sig.remove(SIZE(sig)-1), bits_removed++;
@ -141,31 +154,44 @@ struct WreduceWorker
work_queue_bits.insert(sig[SIZE(sig)-1]), sig.remove(SIZE(sig)-1), bits_removed++; work_queue_bits.insert(sig[SIZE(sig)-1]), sig.remove(SIZE(sig)-1), bits_removed++;
} }
if (bits_removed) { if (bits_removed == 0)
log("Removed top %d bits (of %d) from port %c of cell %s.%s (%s).\n", return false;
bits_removed, SIZE(sig) + bits_removed, port, log_id(module), log_id(cell), log_id(cell->type));
cell->setPort(stringf("\\%c", port), sig); log("Removed top %d bits (of %d) from port %c of cell %s.%s (%s).\n",
} bits_removed, SIZE(sig) + bits_removed, port, log_id(module), log_id(cell), log_id(cell->type));
cell->setPort(stringf("\\%c", port), sig);
return true;
} }
void run_cell(Cell *cell) bool run_cell(Cell *cell)
{ {
if (!cell->type.in(config->supported_cell_types)) bool did_something = false;
return;
if (cell->type.in("$mux", "$pmux", "$safe_pmux")) { if (!cell->type.in(config->supported_cell_types))
run_cell_mux(cell); return false;
return;
if (cell->type.in("$mux", "$pmux", "$safe_pmux"))
return run_cell_mux(cell);
// Reduce size of ports A and B based on constant input bits and size of output port
int max_port_a_size = cell->hasPort("\\A") ? SIZE(cell->getPort("\\A")) : -1;
int max_port_b_size = cell->hasPort("\\B") ? SIZE(cell->getPort("\\B")) : -1;
if (cell->type.in("$not", "$pos", "$bu0", "$neg", "$and", "$or", "$xor", "$add", "$sub")) {
max_port_a_size = std::min(max_port_a_size, SIZE(cell->getPort("\\Y")));
max_port_b_size = std::min(max_port_b_size, SIZE(cell->getPort("\\Y")));
} }
if (cell->type.in("$shl", "$shr", "$sshl", "$sshr")) if (max_port_a_size >= 0)
cell->setParam("\\B_SIGNED", false); did_something = run_reduce_inport(cell, 'A', max_port_a_size) || did_something;
if (cell->hasParam("\\A_SIGNED")) if (max_port_b_size >= 0)
run_reduce_inport(cell, 'A'); did_something = run_reduce_inport(cell, 'B', max_port_b_size) || did_something;
if (cell->hasParam("\\B_SIGNED"))
run_reduce_inport(cell, 'B'); // Reduce size of port Y based on sizes for A and B and unused bits in Y
SigSpec sig = mi.sigmap(cell->getPort("\\Y")); SigSpec sig = mi.sigmap(cell->getPort("\\Y"));
@ -208,9 +234,13 @@ struct WreduceWorker
log("Removed top %d bits (of %d) from port Y of cell %s.%s (%s).\n", log("Removed top %d bits (of %d) from port Y of cell %s.%s (%s).\n",
bits_removed, SIZE(sig) + bits_removed, log_id(module), log_id(cell), log_id(cell->type)); bits_removed, SIZE(sig) + bits_removed, log_id(module), log_id(cell), log_id(cell->type));
cell->setPort("\\Y", sig); cell->setPort("\\Y", sig);
did_something = true;
} }
cell->fixup_parameters(); if (did_something)
cell->fixup_parameters();
return did_something;
} }
void run() void run()
@ -222,7 +252,7 @@ struct WreduceWorker
{ {
work_queue_bits.clear(); work_queue_bits.clear();
for (auto c : work_queue_cells) for (auto c : work_queue_cells)
run_cell(c); while (run_cell(c)) { }
work_queue_cells.clear(); work_queue_cells.clear();
for (auto bit : work_queue_bits) for (auto bit : work_queue_bits)