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clockgate: refactor

This commit is contained in:
Emil J. Tywoniak 2024-11-18 12:50:25 +01:00
parent b08441d95c
commit e6793da9a0
1 changed files with 20 additions and 35 deletions
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55
passes/techmap/clockgate.cc
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@ -50,10 +50,7 @@ static std::pair<std::optional<ClockGateCell>, std::optional<ClockGateCell>>
auto ast = libparser.ast;
// We will pick the most suitable ICG absed on tie_lo count and area
struct ICGRankable {
ClockGateCell icg;
double area;
};
struct ICGRankable : public ClockGateCell { double area; };
std::optional<ICGRankable> best_pos;
std::optional<ICGRankable> best_neg;
@ -78,32 +75,19 @@ static std::pair<std::optional<ClockGateCell>, std::optional<ClockGateCell>>
auto cell_name = cell->args[0];
auto icg_kind = icg_kind_ast->value;
std::vector<std::string> kind_tags;
std::stringstream ss(icg_kind);
std::string tag;
while (std::getline(ss, tag, '_')) {
kind_tags.push_back(tag);
}
if ((kind_tags.size() < 2) || (kind_tags.size() > 4))
log_error("Malformed liberty file - invalid clock_gating_integrated_cell value %s in cell %s\n",
icg_kind.c_str(), cell_name.c_str());
auto internal = kind_tags[0];
if (internal != "latch") {
// TODO Is this expected behavior?
log_warning("Skipping ICG cell %s - not latch-based\n", cell_name.c_str());
continue;
}
auto clk_pol_tag = kind_tags[1];
auto starts_with = [&](std::string prefix) {
return icg_kind.compare(0, prefix.size(), prefix) == 0;
};
bool clk_pol;
if (clk_pol_tag == "posedge") {
if (icg_kind == "latch_posedge" || starts_with("latch_posedge_")) {
clk_pol = true;
} else if (clk_pol_tag == "negedge") {
} else if (icg_kind == "latch_negedge" || starts_with("latch_negedge_")) {
clk_pol = false;
} else {
log_error("Malformed liberty file - invalid clock_gating_integrated_cell value %s in cell %s\n",
icg_kind.c_str(), cell_name.c_str());
log("Ignoring ICG primitive %s of kind '%s'\n", cell_name.c_str(), icg_kind.c_str());
continue;
}
log_debug("maybe valid icg: %s\n", cell_name.c_str());
ClockGateCell icg_interface;
icg_interface.name = RTLIL::escape_id(cell_name);
@ -112,7 +96,6 @@ static std::pair<std::optional<ClockGateCell>, std::optional<ClockGateCell>>
if (pin->id != "pin" || pin->args.size() != 1)
continue;
log("Check pin %s\n", pin->args[0].c_str());
if (auto clk = pin->find("clock_gate_clock_pin")) {
if (!icg_interface.clk_in_pin.empty())
log_error("Malformed liberty file - multiple clock_gate_clock_pin in cell %s\n",
@ -162,15 +145,17 @@ static std::pair<std::optional<ClockGateCell>, std::optional<ClockGateCell>>
bool winning = false;
if (icg_to_beat) {
log_debug("ties: %zu ? %zu\n", icg_to_beat->icg.tie_lo_pins.size(),
log_debug("ties: %zu ? %zu\n", icg_to_beat->tie_lo_pins.size(),
icg_interface.tie_lo_pins.size());
log_debug("area: %f ? %f\n", icg_to_beat->area, area);
if (icg_to_beat->icg.tie_lo_pins.size() != icg_interface.tie_lo_pins.size())
winning = icg_to_beat->icg.tie_lo_pins.size() > icg_interface.tie_lo_pins.size();
else
winning = icg_to_beat->area > area;
// Prefer fewer test enables over area reduction (unlikely to matter)
auto goal = std::make_pair(icg_to_beat->tie_lo_pins.size(), icg_to_beat->area);
auto cost = std::make_pair(icg_interface.tie_lo_pins.size(), area);
winning = cost < goal;
if (winning)
log_debug("%s beats %s\n", icg_interface.name.c_str(), icg_to_beat->icg.name.c_str());
log_debug("%s beats %s\n", icg_interface.name.c_str(), icg_to_beat->name.c_str());
} else {
log_debug("%s is the first of its polarity\n", icg_interface.name.c_str());
winning = true;
@ -184,12 +169,12 @@ static std::pair<std::optional<ClockGateCell>, std::optional<ClockGateCell>>
std::optional<ClockGateCell> pos;
std::optional<ClockGateCell> neg;
if (best_pos) {
log("Selected rising edge ICG %s\n", best_pos->icg.name.c_str());
pos.emplace(best_pos->icg);
log("Selected rising edge ICG %s\n", best_pos->name.c_str());
pos.emplace(*best_pos);
}
if (best_neg) {
log("Selected falling edge ICG %s\n", best_neg->icg.name.c_str());
neg.emplace(best_neg->icg);
log("Selected falling edge ICG %s\n", best_neg->name.c_str());
neg.emplace(*best_neg);
}
return std::make_pair(pos, neg);
}