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// SPDX-License-Identifier: GPL-3.0-or-later
#include "rcc/CodeGen/LiveInterval.h"
#include <algorithm>
#include <cstddef>
#include <limits>
#include <ranges>
#include <unordered_set>
namespace rcc {
const LiveSegment *LiveRange::segmentAt(SlotIndex Position) const noexcept {
const auto Candidate = std::ranges::upper_bound(
Segments, Position, {}, [](const LiveSegment &Segment) { return Segment.Start; });
if (Candidate == Segments.begin())
return nullptr;
const LiveSegment &Previous = *std::prev(Candidate);
return Previous.contains(Position) ? &Previous : nullptr;
}
const LiveValueNumber *LiveRange::value(LiveValueNumberID ID) const noexcept {
if (!ID.isValid() || ID.value() > Values.size())
return nullptr;
const LiveValueNumber &Result = Values[ID.value() - 1U];
return Result.ID == ID ? &Result : nullptr;
}
const LiveValueNumber *LiveRange::valueAt(SlotIndex Position) const noexcept {
const LiveSegment *Segment = segmentAt(Position);
return Segment == nullptr ? nullptr : value(Segment->Value);
}
bool LiveRange::liveAt(SlotIndex Position) const noexcept {
return segmentAt(Position) != nullptr;
}
bool LiveRange::overlaps(const LiveRange &Other) const noexcept {
std::size_t Left = 0;
std::size_t Right = 0;
while (Left < Segments.size() && Right < Other.Segments.size()) {
if (Segments[Left].overlaps(Other.Segments[Right]))
return true;
if (Segments[Left].End <= Other.Segments[Right].Start)
++Left;
else
++Right;
}
return false;
}
Expected<LiveValueNumberID> LiveRange::createValue(SlotIndex Definition, LiveValueState State,
std::optional<MachineInstrStableID> Origin) {
if (!Definition.isValid())
return makeUnexpected(ErrorCode::InvalidArgument, "live value requires a valid definition");
if (Values.size() >= std::numeric_limits<std::uint32_t>::max())
return makeUnexpected(ErrorCode::Unsupported, "live value-number space is exhausted");
const LiveValueNumberID ID =
LiveValueNumberID::fromValue(static_cast<std::uint32_t>(Values.size() + 1U));
Values.push_back({ID, Definition, State, Origin});
return ID;
}
Expected<void> LiveRange::addSegment(LiveSegment Segment) {
if (!Segment.Start.isValid() || !Segment.End.isValid() || Segment.empty() ||
value(Segment.Value) == nullptr) {
return makeUnexpected(ErrorCode::InvalidArgument,
"live segment requires ordered indexes and a known value number");
}
std::vector<LiveSegment> Candidate = Segments;
Candidate.push_back(Segment);
std::ranges::sort(Candidate, [](const LiveSegment &Left, const LiveSegment &Right) {
if (Left.Start != Right.Start)
return Left.Start < Right.Start;
return Left.End < Right.End;
});
for (std::size_t Index = 1; Index < Candidate.size(); ++Index) {
if (Candidate[Index].Start < Candidate[Index - 1U].End &&
Candidate[Index].Value != Candidate[Index - 1U].Value) {
return makeUnexpected(ErrorCode::VerificationError,
"live segments with different values overlap");
}
}
Segments = std::move(Candidate);
mergeAdjacent();
return {};
}
Expected<void> LiveRange::extend(LiveValueNumberID Value, SlotIndex Start, SlotIndex End) {
return addSegment({Start, End, Value});
}
Expected<void> LiveRange::remove(SlotIndex Start, SlotIndex End) {
if (!Start.isValid() || !End.isValid() || !(Start < End)) {
return makeUnexpected(ErrorCode::InvalidArgument, "removed live range must be nonempty");
}
std::vector<LiveSegment> Result;
for (const LiveSegment &Segment : Segments) {
if (!(Segment.Start < End && Start < Segment.End)) {
Result.push_back(Segment);
continue;
}
if (Segment.Start < Start)
Result.push_back({Segment.Start, Start, Segment.Value});
if (End < Segment.End)
Result.push_back({End, Segment.End, Segment.Value});
}
Segments = std::move(Result);
mergeAdjacent();
return {};
}
Expected<void> LiveRange::shrinkToUses(std::span<const SlotIndex> Uses) {
std::vector<LiveSegment> Result;
for (const LiveSegment &Segment : Segments) {
const LiveValueNumber *Value = value(Segment.Value);
if (Value == nullptr)
return makeUnexpected(ErrorCode::VerificationError,
"live segment references an unknown value number");
std::optional<SlotIndex> LastUse;
for (const SlotIndex Use : Uses) {
if (Segment.contains(Use) && (!LastUse || *LastUse < Use))
LastUse = Use;
}
if (!LastUse) {
if (Value->State == LiveValueState::Unused)
Result.push_back(Segment);
continue;
}
SlotIndex NewEnd = LastUse->deadSlot();
if (Segment.End < NewEnd)
NewEnd = Segment.End;
if (Segment.Start < NewEnd)
Result.push_back({Segment.Start, NewEnd, Segment.Value});
}
Segments = std::move(Result);
mergeAdjacent();
return verify();
}
Expected<void> LiveRange::verify() const {
std::unordered_set<LiveValueNumberID> IDs;
for (std::size_t Index = 0; Index < Values.size(); ++Index) {
const LiveValueNumber &Value = Values[Index];
if (!Value.ID.isValid() || Value.ID.value() != Index + 1U || !IDs.insert(Value.ID).second ||
!Value.Definition.isValid()) {
return makeUnexpected(ErrorCode::VerificationError,
"live range contains an invalid value number");
}
}
for (std::size_t Index = 0; Index < Segments.size(); ++Index) {
const LiveSegment &Segment = Segments[Index];
if (!Segment.Start.isValid() || !Segment.End.isValid() || Segment.empty() ||
value(Segment.Value) == nullptr) {
return makeUnexpected(ErrorCode::VerificationError, "live range contains an invalid segment");
}
if (Index != 0 && Segments[Index - 1U].End > Segment.Start) {
return makeUnexpected(ErrorCode::VerificationError,
"live range segments are not ordered and disjoint");
}
}
return {};
}
void LiveRange::mergeAdjacent() {
if (Segments.empty())
return;
std::vector<LiveSegment> Result;
Result.reserve(Segments.size());
Result.push_back(Segments.front());
for (std::size_t Index = 1; Index < Segments.size(); ++Index) {
LiveSegment &Previous = Result.back();
const LiveSegment &Current = Segments[Index];
if (Current.Value == Previous.Value && Current.Start <= Previous.End) {
if (Previous.End < Current.End)
Previous.End = Current.End;
continue;
}
Result.push_back(Current);
}
Segments = std::move(Result);
}
} // namespace rcc
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