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// SPDX-License-Identifier: GPL-3.0-or-later
#ifndef RCC_CODEGEN_PBQP_SOLUTION_H
#define RCC_CODEGEN_PBQP_SOLUTION_H
#include "rcc/CodeGen/PBQP/Graph.h"
#include "rcc/Support/Error.h"
#include <cstddef>
#include <limits>
#include <optional>
#include <span>
#include <vector>
namespace rcc::pbqp {
class Solution final {
public:
explicit Solution(std::size_t NodeCount)
: Selections(NodeCount, std::numeric_limits<std::size_t>::max()) {}
[[nodiscard]] Expected<void> setSelection(NodeID ID, std::size_t Selection) {
if (!ID.isValid() || ID.value() >= Selections.size())
return makeUnexpected(ErrorCode::InvalidArgument, "PBQP solution received an unknown node");
Selections[ID.value()] = Selection;
return {};
}
[[nodiscard]] std::optional<std::size_t> selection(NodeID ID) const noexcept {
if (!ID.isValid() || ID.value() >= Selections.size() ||
Selections[ID.value()] == std::numeric_limits<std::size_t>::max())
return std::nullopt;
return Selections[ID.value()];
}
[[nodiscard]] std::span<const std::size_t> selections() const noexcept {
return Selections;
}
[[nodiscard]] Cost totalCost() const noexcept {
return TotalCost;
}
void setTotalCost(Cost Value) noexcept {
TotalCost = Value;
}
[[nodiscard]] Expected<void> verify(const Graph &Problem) const {
if (Selections.size() != Problem.nodeCount())
return makeUnexpected(ErrorCode::VerificationError, "PBQP solution has the wrong node count");
Cost Total = 0;
for (const Node &NodeValue : Problem.nodes()) {
const auto Selection = selection(NodeValue.ID);
if (!Selection)
return makeUnexpected(ErrorCode::VerificationError,
"PBQP solution omits a valid node selection");
const std::size_t SelectedOption = Selection.value();
if (SelectedOption >= NodeValue.Costs.size())
return makeUnexpected(ErrorCode::VerificationError,
"PBQP solution selects an invalid node option");
Total = addCosts(Total, NodeValue.Costs[SelectedOption]);
}
for (const Edge &EdgeValue : Problem.edges()) {
const auto FirstSelection = selection(EdgeValue.First);
const auto SecondSelection = selection(EdgeValue.Second);
if (!FirstSelection || !SecondSelection) {
return makeUnexpected(ErrorCode::VerificationError,
"PBQP solution omits an edge endpoint selection");
}
Total = addCosts(Total, EdgeValue.Costs.at(FirstSelection.value(), SecondSelection.value()));
}
if (isInfinite(Total))
return makeUnexpected(ErrorCode::RegisterAllocationFailed,
"PBQP problem has no finite solution");
if (Total != TotalCost)
return makeUnexpected(ErrorCode::VerificationError, "PBQP solution cost is inconsistent");
return {};
}
private:
std::vector<std::size_t> Selections;
Cost TotalCost = 0;
};
} // namespace rcc::pbqp
#endif // RCC_CODEGEN_PBQP_SOLUTION_H
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