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abc9: fix SCC issues (#2694) 

* xilinx: add SCC test for DSP48E1

* xilinx: Gate DSP48E1 being a whitebox behind ALLOW_WHITEBOX_DSP48E1

Have a test that checks it works through ABC9 when enabled

* abc9 to break SCCs using $__ABC9_SCC_BREAKER module

* Add test

* abc9_ops: remove refs to (* abc9_keep *) on wires

* abc9_ops: do not bypass cells in an SCC

* Add myself to CODEOWNERS for abc9*

* Fix compile

* abc9_ops: run -prep_hier before scc

* Fix tests

* Remove bug reference pending fix

* abc9: fix for -prep_hier -dff

* xaiger: restore PI handling

* abc9_ops: -prep_xaiger sigmap

* abc9_ops: -mark_scc -> -break_scc

* abc9: eliminate hard-coded abc9.box from tests

Also tidy up

* Address review
This commit is contained in:
Eddie Hung 2021-03-29 22:01:57 -07:00 committed by GitHub
parent 687f381b69
commit 55dc5a4e4f
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9 changed files with 94 additions and 45 deletions
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2
CODEOWNERS
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@ -16,6 +16,8 @@ backends/cxxrtl/ @whitequark
passes/cmds/bugpoint.cc @whitequark
passes/techmap/flowmap.cc @whitequark
passes/opt/opt_lut.cc @whitequark
passes/techmap/abc9*.cc @eddiehung
backends/aiger/xaiger.cc @eddiehung
## External Contributors

9
backends/aiger/xaiger.cc
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@ -156,7 +156,7 @@ struct XAigerWriter
// promote keep wires
for (auto wire : module->wires())
if (wire->get_bool_attribute(ID::keep) || wire->get_bool_attribute(ID::abc9_keep))
if (wire->get_bool_attribute(ID::keep))
sigmap.add(wire);
for (auto wire : module->wires()) {
@ -177,11 +177,10 @@ struct XAigerWriter
undriven_bits.insert(bit);
unused_bits.insert(bit);
bool keep = wire->get_bool_attribute(ID::abc9_keep);
if (wire->port_input || keep)
if (wire->port_input)
input_bits.insert(bit);
keep = keep || wire->get_bool_attribute(ID::keep);
bool keep = wire->get_bool_attribute(ID::keep);
if (wire->port_output || keep) {
if (bit != wirebit)
alias_map[wirebit] = bit;
@ -433,7 +432,7 @@ struct XAigerWriter
if (bit == State::Sx)
continue;
if (aig_map.count(bit))
log_error("Visited AIG node more than once; this could be a combinatorial loop that has not been broken - see Yosys bug 2530\n");
log_error("Visited AIG node more than once; this could be a combinatorial loop that has not been broken\n");
aig_map[bit] = 2*aig_m;
}

17
passes/techmap/abc9.cc
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@ -283,9 +283,14 @@ struct Abc9Pass : public ScriptPass
if (check_label("map")) {
if (help_mode)
run("abc9_ops -prep_hier -prep_bypass [-prep_dff -dff]", "(option if -dff)");
run("abc9_ops -prep_hier [-dff]", "(option if -dff)");
else
run(stringf("abc9_ops -prep_hier -prep_bypass %s", dff_mode ? "-prep_dff -dff" : ""));
run(stringf("abc9_ops -prep_hier %s", dff_mode ? "-dff" : ""));
run("scc -specify -set_attr abc9_scc_id {}");
if (help_mode)
run("abc9_ops -prep_bypass [-prep_dff]", "(option if -dff)");
else
run(stringf("abc9_ops -prep_bypass %s", dff_mode ? "-prep_dff" : ""));
if (dff_mode) {
run("design -copy-to $abc9_map @$abc9_flops", "(only if -dff)");
run("select -unset $abc9_flops", " (only if -dff)");
@ -330,20 +335,20 @@ struct Abc9Pass : public ScriptPass
run("design -stash $abc9_map");
run("design -load $abc9");
run("design -delete $abc9");
// Insert bypass modules (and perform +/abc9_map.v transformations), except for those cells part of a SCC
if (help_mode)
run("techmap -wb -max_iter 1 -map %$abc9_map -map +/abc9_map.v [-D DFF]", "(option if -dff)");
else
run(stringf("techmap -wb -max_iter 1 -map %%$abc9_map -map +/abc9_map.v %s", dff_mode ? "-D DFF" : ""));
run(stringf("techmap -wb -max_iter 1 -map %%$abc9_map -map +/abc9_map.v %s a:abc9_scc_id %%n", dff_mode ? "-D DFF" : ""));
run("design -delete $abc9_map");
}
if (check_label("pre")) {
run("read_verilog -icells -lib -specify +/abc9_model.v");
run("scc -specify -set_attr abc9_scc_id {}");
if (help_mode)
run("abc9_ops -mark_scc -prep_delays -prep_xaiger [-dff]", "(option for -dff)");
run("abc9_ops -break_scc -prep_delays -prep_xaiger [-dff]", "(option for -dff)");
else
run("abc9_ops -mark_scc -prep_delays -prep_xaiger" + std::string(dff_mode ? " -dff" : ""));
run("abc9_ops -break_scc -prep_delays -prep_xaiger" + std::string(dff_mode ? " -dff" : ""));
if (help_mode)
run("abc9_ops -prep_lut <maxlut>", "(skip if -lut or -luts)");
else if (!lut_mode)

63
passes/techmap/abc9_ops.cc
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@ -544,18 +544,31 @@ void prep_dff_unmap(RTLIL::Design *design)
}
}
void mark_scc(RTLIL::Module *module)
void break_scc(RTLIL::Module *module)
{
// For every unique SCC found, (arbitrarily) find the first
// cell in the component, and replace its output connections
// with a new wire driven by the old connection but with a
// special (* abc9_keep *) attribute set (which is used by
// write_xaiger to break this wire into PI and POs)
// cell in the component, and interrupt all its output connections
// with the $__ABC9_SCC_BREAKER cell
// Do not break SCCs which have a cell instantiating an abc9_bypass-able
// module (but which wouldn't have been bypassed)
auto design = module->design;
pool<RTLIL::Cell*> scc_cells;
pool<RTLIL::Const> ids_seen;
for (auto cell : module->cells()) {
auto it = cell->attributes.find(ID::abc9_scc_id);
if (it == cell->attributes.end())
continue;
scc_cells.insert(cell);
auto inst_module = design->module(cell->type);
if (inst_module && inst_module->has_attribute(ID::abc9_bypass))
ids_seen.insert(it->second);
}
SigSpec I, O;
for (auto cell : scc_cells) {
auto it = cell->attributes.find(ID::abc9_scc_id);
log_assert(it != cell->attributes.end());
auto id = it->second;
auto r = ids_seen.insert(id);
cell->attributes.erase(it);
@ -565,12 +578,21 @@ void mark_scc(RTLIL::Module *module)
if (c.second.is_fully_const()) continue;
if (cell->output(c.first)) {
Wire *w = module->addWire(NEW_ID, GetSize(c.second));
w->set_bool_attribute(ID::abc9_keep);
module->connect(w, c.second);
I.append(w);
O.append(c.second);
c.second = w;
}
}
}
if (!I.empty())
{
auto cell = module->addCell(NEW_ID, ID($__ABC9_SCC_BREAKER));
log_assert(GetSize(I) == GetSize(O));
cell->setParam(ID::WIDTH, GetSize(I));
cell->setPort(ID::I, std::move(I));
cell->setPort(ID::O, std::move(O));
}
}
void prep_delays(RTLIL::Design *design, bool dff_mode)
@ -721,10 +743,8 @@ void prep_xaiger(RTLIL::Module *module, bool dff)
bit_users[bit].insert(cell->name);
if (cell->output(conn.first) && !abc9_flop)
for (const auto &chunk : conn.second.chunks())
if (!chunk.wire->get_bool_attribute(ID::abc9_keep))
for (auto b : sigmap(SigSpec(chunk)))
bit_drivers[b].insert(cell->name);
for (auto bit : sigmap(conn.second))
bit_drivers[bit].insert(cell->name);
}
toposort.node(cell->name);
}
@ -1424,7 +1444,6 @@ void reintegrate(RTLIL::Module *module, bool dff_mode)
RTLIL::Wire *mapped_wire = mapped_mod->wire(port);
RTLIL::Wire *wire = module->wire(port);
log_assert(wire);
wire->attributes.erase(ID::abc9_keep);
RTLIL::Wire *remap_wire = module->wire(remap_name(port));
RTLIL::SigSpec signal(wire, remap_wire->start_offset-wire->start_offset, GetSize(remap_wire));
@ -1587,11 +1606,11 @@ struct Abc9OpsPass : public Pass {
log(" insert `$__ABC9_DELAY' blackbox cells into the design to account for\n");
log(" certain required times.\n");
log("\n");
log(" -mark_scc\n");
log(" -break_scc\n");
log(" for an arbitrarily chosen cell in each unique SCC of each selected module\n");
log(" (tagged with an (* abc9_scc_id = <int> *) attribute), temporarily mark all\n");
log(" wires driven by this cell's outputs with a (* keep *) attribute in order\n");
log(" to break the SCC. this temporary attribute will be removed on -reintegrate.\n");
log(" (tagged with an (* abc9_scc_id = <int> *) attribute) interrupt all wires\n");
log(" driven by this cell's outputs with a temporary $__ABC9_SCC_BREAKER cell\n");
log(" to break the SCC.\n");
log("\n");
log(" -prep_xaiger\n");
log(" prepare the design for XAIGER output. this includes computing the\n");
@ -1628,7 +1647,7 @@ struct Abc9OpsPass : public Pass {
bool check_mode = false;
bool prep_delays_mode = false;
bool mark_scc_mode = false;
bool break_scc_mode = false;
bool prep_hier_mode = false;
bool prep_bypass_mode = false;
bool prep_dff_mode = false, prep_dff_submod_mode = false, prep_dff_unmap_mode = false;
@ -1650,8 +1669,8 @@ struct Abc9OpsPass : public Pass {
valid = true;
continue;
}
if (arg == "-mark_scc") {
mark_scc_mode = true;
if (arg == "-break_scc") {
break_scc_mode = true;
valid = true;
continue;
}
@ -1727,7 +1746,7 @@ struct Abc9OpsPass : public Pass {
extra_args(args, argidx, design);
if (!valid)
log_cmd_error("At least one of -check, -mark_scc, -prep_{delays,xaiger,dff[123],lut,box}, -write_{lut,box}, -reintegrate must be specified.\n");
log_cmd_error("At least one of -check, -break_scc, -prep_{delays,xaiger,dff[123],lut,box}, -write_{lut,box}, -reintegrate must be specified.\n");
if (dff_mode && !check_mode && !prep_hier_mode && !prep_delays_mode && !prep_xaiger_mode && !reintegrate_mode)
log_cmd_error("'-dff' option is only relevant for -prep_{hier,delay,xaiger} or -reintegrate.\n");
@ -1764,8 +1783,8 @@ struct Abc9OpsPass : public Pass {
write_lut(mod, write_lut_dst);
if (!write_box_dst.empty())
write_box(mod, write_box_dst);
if (mark_scc_mode)
mark_scc(mod);
if (break_scc_mode)
break_scc(mod);
if (prep_xaiger_mode)
prep_xaiger(mod, dff_mode);
if (reintegrate_mode)

4
techlibs/common/abc9_model.v
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@ -6,6 +6,10 @@ module $__ABC9_DELAY (input I, output O);
endspecify
endmodule
module $__ABC9_SCC_BREAKER (input [WIDTH-1:0] I, output [WIDTH-1:0] O);
parameter WIDTH = 0;
endmodule
(* abc9_flop, abc9_box, lib_whitebox *)
module $__DFF_N__$abc9_flop (input C, D, Q, output n1);
assign n1 = D;

5
techlibs/common/abc9_unmap.v
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@ -9,3 +9,8 @@ module $__DFF_x__$abc9_flop (input C, D, (* init = 1'b0 *) input Q, output n1);
$error("Unrecognised _TECHMAP_CELLTYPE_");
endgenerate
endmodule
module $__ABC9_SCC_BREAKER (input [WIDTH-1:0] I, output [WIDTH-1:0] O);
parameter WIDTH = 0;
assign O = I;
endmodule

3
tests/simple_abc9/abc9.box
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@ -1,3 +0,0 @@
MUXF8 1 0 3 1
#I0 I1 S
0 0 0 # O

24
tests/simple_abc9/abc9.v
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@ -213,7 +213,7 @@ module arbiter (clk, rst, request, acknowledge, grant, grant_valid, grant_encode
input rst;
endmodule
(* abc9_box_id=1, blackbox *)
(* abc9_box, blackbox *)
module MUXF8(input I0, I1, S, output O);
specify
(I0 => O) = 0;
@ -300,15 +300,29 @@ endmodule
module abc9_test036(input A, B, S, output [1:0] O);
(* keep *)
MUXF8 m (
.I0(I0),
.I1(I1),
.I0(A),
.I1(B),
.O(O[0]),
.S(S)
);
MUXF8 m2 (
.I0(I0),
.I1(I1),
.I0(A),
.I1(B),
.O(O[1]),
.S(S)
);
endmodule
(* abc9_box, whitebox *)
module MUXF7(input I0, I1, S, output O);
assign O = S ? I1 : I0;
specify
(I0 => O) = 0;
(I1 => O) = 0;
(S => O) = 0;
endspecify
endmodule
module abc9_test037(output o);
MUXF7 m(.I0(1'b1), .I1(1'b0), .S(o), .O(o));
endmodule

12
tests/simple_abc9/run-test.sh
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@ -37,14 +37,18 @@ done
cp ../simple/*.v .
cp ../simple/*.sv .
rm specify.v # bug 2675
DOLLAR='?'
exec ${MAKE:-make} -f ../tools/autotest.mk $seed *.v *.sv EXTRA_FLAGS="-n 300 -p '\
exec ${MAKE:-make} -f ../tools/autotest.mk $seed *.v *.sv EXTRA_FLAGS="-f \"verilog -noblackbox -specify\" -n 300 -p '\
read_verilog -icells -lib +/abc9_model.v; \
hierarchy; \
synth -run coarse; \
opt -full; \
techmap; \
abc9 -lut 4 -box ../abc9.box; \
abc9 -lut 4; \
clean; \
check -assert; \
check -assert * abc9_test037 %d; \
select -assert-none t:${DOLLAR}_NOT_ t:${DOLLAR}_AND_ %%; \
setattr -mod -unset blackbox'"
setattr -mod -unset blackbox -unset whitebox'"
# NOTE: Skip 'check -assert' on abc9_test037 because it intentionally has a combinatorial loop