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grt: add prevent division by zero and overflow when computing resistance cost #10034

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Merged
maliberty merged 2 commits into from
Apr 6, 2026
Merged

grt: add prevent division by zero and overflow when computing resistance cost #10034

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grt: add prevent division by zero and overflow when computing resista…
eder-matheus Apr 2, 2026
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grt: apply gemini suggestions
eder-matheus Apr 3, 2026
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22 changes: 16 additions & 6 deletions src/grt/src/fastroute/src/utility.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -533,10 +533,15 @@ int FastRouteCore::getWireCost(const int layer, const int length, FrNet* net)

odb::dbTechLayer* default_layer = getTechLayer(0, false);

double default_resistance = default_layer->getResistance();
float final_resistance = getWireResistance(layer, length, net);
const double default_resistance = default_layer->getResistance();
// Prevent division by zero when layer resistance is not defined.
if (default_resistance <= 0.0) {
return 0;
}

return std::ceil(final_resistance / default_resistance);
const float final_resistance = getWireResistance(layer, length, net);
const double cost = std::ceil(final_resistance / default_resistance);
return static_cast<int>(std::min<double>(cost, BIG_INT));
}

// Get via resistance in ohms going from layer A to layer B
Expand Down Expand Up @@ -569,10 +574,15 @@ int FastRouteCore::getViaCost(const int from_layer, const int to_layer)
}

// Calculate total resistance
float total_via_resistance = getViaResistance(from_layer, to_layer);
float default_res = getTechLayer(0, true)->getResistance();
const float default_res = getTechLayer(0, true)->getResistance();
// Prevent division by zero when layer resistance is not defined.
if (default_res <= 0.0) {
return 0;
}

return std::ceil(total_via_resistance / default_res);
const float total_via_resistance = getViaResistance(from_layer, to_layer);
const double cost = std::ceil(total_via_resistance / default_res);
return static_cast<int>(std::min<double>(cost, BIG_INT));
}

void FastRouteCore::updateWorstMetrics(FrNet* net)
Expand Down
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