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//===- ConstantRangeList.cpp - ConstantRangeList implementation -----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/IR/ConstantRangeList.h"
#include <cstddef>
using namespace llvm;
bool ConstantRangeList::isOrderedRanges(ArrayRef<ConstantRange> RangesRef) {
if (RangesRef.empty())
return true;
auto Range = RangesRef[0];
if (Range.getLower().sge(Range.getUpper()))
return false;
for (unsigned i = 1; i < RangesRef.size(); i++) {
auto CurRange = RangesRef[i];
auto PreRange = RangesRef[i - 1];
if (CurRange.getLower().sge(CurRange.getUpper()) ||
CurRange.getLower().sle(PreRange.getUpper()))
return false;
}
return true;
}
std::optional<ConstantRangeList>
ConstantRangeList::getConstantRangeList(ArrayRef<ConstantRange> RangesRef) {
if (!isOrderedRanges(RangesRef))
return std::nullopt;
return ConstantRangeList(RangesRef);
}
void ConstantRangeList::insert(const ConstantRange &NewRange) {
if (NewRange.isEmptySet())
return;
assert(!NewRange.isFullSet() && "Do not support full set");
assert(NewRange.getLower().slt(NewRange.getUpper()));
// Handle common cases.
if (empty() || Ranges.back().getUpper().slt(NewRange.getLower())) {
Ranges.push_back(NewRange);
return;
}
assert(getBitWidth() == NewRange.getBitWidth());
if (NewRange.getUpper().slt(Ranges.front().getLower())) {
Ranges.insert(Ranges.begin(), NewRange);
return;
}
auto LowerBound = lower_bound(
Ranges, NewRange, [](const ConstantRange &a, const ConstantRange &b) {
return a.getLower().slt(b.getLower());
});
if (LowerBound != Ranges.end() && LowerBound->contains(NewRange))
return;
// Slow insert.
SmallVector<ConstantRange, 2> ExistingTail(LowerBound, Ranges.end());
Ranges.erase(LowerBound, Ranges.end());
// Merge consecutive ranges.
if (!Ranges.empty() && NewRange.getLower().sle(Ranges.back().getUpper())) {
APInt NewLower = Ranges.back().getLower();
APInt NewUpper =
APIntOps::smax(NewRange.getUpper(), Ranges.back().getUpper());
Ranges.back() = ConstantRange(NewLower, NewUpper);
} else {
Ranges.push_back(NewRange);
}
for (auto Iter = ExistingTail.begin(); Iter != ExistingTail.end(); Iter++) {
if (Ranges.back().getUpper().slt(Iter->getLower())) {
Ranges.push_back(*Iter);
} else {
APInt NewLower = Ranges.back().getLower();
APInt NewUpper =
APIntOps::smax(Iter->getUpper(), Ranges.back().getUpper());
Ranges.back() = ConstantRange(NewLower, NewUpper);
}
}
}
void ConstantRangeList::subtract(const ConstantRange &SubRange) {
if (SubRange.isEmptySet() || empty())
return;
assert(!SubRange.isFullSet() && "Do not support full set");
assert(SubRange.getLower().slt(SubRange.getUpper()));
assert(getBitWidth() == SubRange.getBitWidth());
// Handle common cases.
if (Ranges.back().getUpper().sle(SubRange.getLower()))
return;
if (SubRange.getUpper().sle(Ranges.front().getLower()))
return;
SmallVector<ConstantRange, 2> Result;
auto AppendRangeIfNonEmpty = [&Result](APInt Start, APInt End) {
if (Start.slt(End))
Result.push_back(ConstantRange(Start, End));
};
for (auto &Range : Ranges) {
if (SubRange.getUpper().sle(Range.getLower()) ||
Range.getUpper().sle(SubRange.getLower())) {
// "Range" and "SubRange" do not overlap.
// L---U : Range
// L---U : SubRange (Case1)
// L---U : SubRange (Case2)
Result.push_back(Range);
} else if (Range.getLower().sle(SubRange.getLower()) &&
SubRange.getUpper().sle(Range.getUpper())) {
// "Range" contains "SubRange".
// L---U : Range
// L-U : SubRange
// Note that ConstantRange::contains(ConstantRange) checks unsigned,
// but we need signed checking here.
AppendRangeIfNonEmpty(Range.getLower(), SubRange.getLower());
AppendRangeIfNonEmpty(SubRange.getUpper(), Range.getUpper());
} else if (SubRange.getLower().sle(Range.getLower()) &&
Range.getUpper().sle(SubRange.getUpper())) {
// "SubRange" contains "Range".
// L-U : Range
// L---U : SubRange
continue;
} else if (Range.getLower().sge(SubRange.getLower()) &&
Range.getLower().sle(SubRange.getUpper())) {
// "Range" and "SubRange" overlap at the left.
// L---U : Range
// L---U : SubRange
AppendRangeIfNonEmpty(SubRange.getUpper(), Range.getUpper());
} else {
// "Range" and "SubRange" overlap at the right.
// L---U : Range
// L---U : SubRange
assert(SubRange.getLower().sge(Range.getLower()) &&
SubRange.getLower().sle(Range.getUpper()));
AppendRangeIfNonEmpty(Range.getLower(), SubRange.getLower());
}
}
Ranges = Result;
}
ConstantRangeList
ConstantRangeList::unionWith(const ConstantRangeList &CRL) const {
// Handle common cases.
if (empty())
return CRL;
if (CRL.empty())
return *this;
assert(getBitWidth() == CRL.getBitWidth() &&
"ConstantRangeList bitwidths don't agree!");
ConstantRangeList Result;
size_t i = 0, j = 0;
// "PreviousRange" tracks the lowest unioned range that is being processed.
// Its lower is fixed and the upper may be updated over iterations.
ConstantRange PreviousRange(getBitWidth(), false);
if (Ranges[i].getLower().slt(CRL.Ranges[j].getLower())) {
PreviousRange = Ranges[i++];
} else {
PreviousRange = CRL.Ranges[j++];
}
// Try to union "PreviousRange" and "CR". If they are disjoint, push
// "PreviousRange" to the result and assign it to "CR", a new union range.
// Otherwise, update the upper of "PreviousRange" to cover "CR". Note that,
// the lower of "PreviousRange" is always less or equal the lower of "CR".
auto UnionAndUpdateRange = [&PreviousRange,
&Result](const ConstantRange &CR) {
if (PreviousRange.getUpper().slt(CR.getLower())) {
Result.Ranges.push_back(PreviousRange);
PreviousRange = CR;
} else {
PreviousRange = ConstantRange(
PreviousRange.getLower(),
APIntOps::smax(PreviousRange.getUpper(), CR.getUpper()));
}
};
while (i < size() || j < CRL.size()) {
if (j == CRL.size() ||
(i < size() && Ranges[i].getLower().slt(CRL.Ranges[j].getLower()))) {
// Merge PreviousRange with this.
UnionAndUpdateRange(Ranges[i++]);
} else {
// Merge PreviousRange with CRL.
UnionAndUpdateRange(CRL.Ranges[j++]);
}
}
Result.Ranges.push_back(PreviousRange);
return Result;
}
ConstantRangeList
ConstantRangeList::intersectWith(const ConstantRangeList &CRL) const {
// Handle common cases.
if (empty())
return *this;
if (CRL.empty())
return CRL;
assert(getBitWidth() == CRL.getBitWidth() &&
"ConstantRangeList bitwidths don't agree!");
ConstantRangeList Result;
size_t i = 0, j = 0;
while (i < size() && j < CRL.size()) {
auto &Range = this->Ranges[i];
auto &OtherRange = CRL.Ranges[j];
// The intersection of two Ranges is (max(lowers), min(uppers)), and it's
// possible that max(lowers) > min(uppers) if they don't have intersection.
// Add the intersection to result only if it's non-empty.
// To keep simple, we don't call ConstantRange::intersectWith() as it
// considers the complex upper wrapped case and may result two ranges,
// like (2, 8) && (6, 4) = {(2, 4), (6, 8)}.
APInt Start = APIntOps::smax(Range.getLower(), OtherRange.getLower());
APInt End = APIntOps::smin(Range.getUpper(), OtherRange.getUpper());
if (Start.slt(End))
Result.Ranges.push_back(ConstantRange(Start, End));
// Move to the next Range in one list determined by the uppers.
// For example: A = {(0, 2), (4, 8)}; B = {(-2, 5), (6, 10)}
// We need to intersect three pairs: A0 && B0; A1 && B0; A1 && B1.
if (Range.getUpper().slt(OtherRange.getUpper()))
i++;
else
j++;
}
return Result;
}
void ConstantRangeList::print(raw_ostream &OS) const {
interleaveComma(Ranges, OS, [&](ConstantRange CR) {
OS << "(" << CR.getLower() << ", " << CR.getUpper() << ")";
});
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void ConstantRangeList::dump() const {
print(dbgs());
dbgs() << '\n';
}
#endif
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