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extract_reduce: Refactor and fix input signal construction. 

Fixes #3047.
This commit is contained in:
Marcelina Kościelnicka 2021-10-21 02:58:10 +02:00
parent a0e9d9fef9
commit e64456f920
2 changed files with 46 additions and 63 deletions
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97
passes/techmap/extract_reduce.cc
View File

@ -224,89 +224,60 @@ struct ExtractReducePass : public Pass
if(consumed_cells.count(head_cell))
continue;
pool<Cell*> cur_supercell;
dict<SigBit, int> sources;
int inner_cells = 0;
std::deque<Cell*> bfs_queue = {head_cell};
while (bfs_queue.size())
{
Cell* x = bfs_queue.front();
bfs_queue.pop_front();
cur_supercell.insert(x);
for (auto port: {ID::A, ID::B}) {
auto bit = sigmap(x->getPort(port)[0]);
auto a = sigmap(x->getPort(ID::A));
log_assert(a.size() == 1);
bool sink_single = sig_to_sink[bit].size() == 1 && !port_sigs.count(bit);
// Must have only one sink unless we're going off chain
// XXX: Check that it is indeed this node?
if( allow_off_chain || (sig_to_sink[a[0]].size() + port_sigs.count(a[0]) == 1) )
{
Cell* cell_a = sig_to_driver[a[0]];
if(cell_a && IsRightType(cell_a, gt))
{
// The cell here is the correct type, and it's definitely driving
// this current cell.
bfs_queue.push_back(cell_a);
}
}
Cell* drv = sig_to_driver[bit];
bool drv_ok = drv && drv->type == head_cell->type;
auto b = sigmap(x->getPort(ID::B));
log_assert(b.size() == 1);
// Must have only one sink
// XXX: Check that it is indeed this node?
if( allow_off_chain || (sig_to_sink[b[0]].size() + port_sigs.count(b[0]) == 1) )
{
Cell* cell_b = sig_to_driver[b[0]];
if(cell_b && IsRightType(cell_b, gt))
{
// The cell here is the correct type, and it's definitely driving only
// this current cell.
bfs_queue.push_back(cell_b);
if (drv_ok && (allow_off_chain || sink_single)) {
inner_cells++;
bfs_queue.push_back(drv);
} else {
sources[bit]++;
}
}
}
log(" Cells:\n");
for (auto x : cur_supercell)
log(" %s\n", x->name.c_str());
if (cur_supercell.size() > 1)
if (inner_cells)
{
// Worth it to create reduce cell
log(" Creating $reduce_* cell!\n");
pool<SigBit> input_pool;
pool<SigBit> input_pool_intermed;
for (auto x : cur_supercell)
{
input_pool.insert(sigmap(x->getPort(ID::A))[0]);
input_pool.insert(sigmap(x->getPort(ID::B))[0]);
input_pool_intermed.insert(sigmap(x->getPort(ID::Y))[0]);
}
SigSpec input;
for (auto b : input_pool)
if (input_pool_intermed.count(b) == 0)
input.append(b);
SigBit output = sigmap(head_cell->getPort(ID::Y)[0]);
auto new_reduce_cell = module->addCell(NEW_ID,
gt == GateType::And ? ID($reduce_and) :
gt == GateType::Or ? ID($reduce_or) :
gt == GateType::Xor ? ID($reduce_xor) : "");
new_reduce_cell->setParam(ID::A_SIGNED, 0);
new_reduce_cell->setParam(ID::A_WIDTH, input.size());
new_reduce_cell->setParam(ID::Y_WIDTH, 1);
new_reduce_cell->setPort(ID::A, input);
new_reduce_cell->setPort(ID::Y, output);
if(allow_off_chain)
consumed_cells.insert(head_cell);
else
{
for (auto x : cur_supercell)
consumed_cells.insert(x);
SigSpec input;
for (auto it : sources) {
bool cond;
if (head_cell->type == ID($_XOR_))
cond = it.second & 1;
else
cond = it.second != 0;
if (cond)
input.append(it.first);
}
if (head_cell->type == ID($_AND_)) {
module->addReduceAnd(NEW_ID, input, output);
} else if (head_cell->type == ID($_OR_)) {
module->addReduceOr(NEW_ID, input, output);
} else if (head_cell->type == ID($_XOR_)) {
module->addReduceXor(NEW_ID, input, output);
} else {
log_assert(false);
}
consumed_cells.insert(head_cell);
}
}
}

12
tests/opt/bug3047.ys Normal file
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@ -0,0 +1,12 @@
read_verilog << EOT
module test (A, B, C, D, Y);
input A, B, C, D;
output Y;
assign Y = A^B^C^D^A;
endmodule
EOT
techmap
equiv_opt -assert extract_reduce