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[DWARF] DWARFDebugLine: replace Sequence::orderByLowPC with orderByHighPC

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In a sorted list of non-overlapping [LowPC,HighPC) ranges, locating an address with
upper_bound on HighPC is simpler than lower_bound on LowPC.

llvm-svn: 358012
This commit is contained in:
Fangrui Song 2019-04-09 15:08:32 +00:00
parent 9bccbf9749
commit 851714ea16
2 changed files with 13 additions and 35 deletions
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6
include/llvm/DebugInfo/DWARF/DWARFDebugLine.h
View File

@ -206,9 +206,9 @@ public:
void reset();
static bool orderByLowPC(const Sequence &LHS, const Sequence &RHS) {
return std::tie(LHS.SectionIndex, LHS.LowPC) <
std::tie(RHS.SectionIndex, RHS.LowPC);
static bool orderByHighPC(const Sequence &LHS, const Sequence &RHS) {
return std::tie(LHS.SectionIndex, LHS.HighPC) <
std::tie(RHS.SectionIndex, RHS.HighPC);
}
bool isValid() const {

42
lib/DebugInfo/DWARF/DWARFDebugLine.cpp
View File

@ -842,7 +842,7 @@ Error DWARFDebugLine::LineTable::parse(
// Sort all sequences so that address lookup will work faster.
if (!Sequences.empty()) {
llvm::sort(Sequences, Sequence::orderByLowPC);
llvm::sort(Sequences, Sequence::orderByHighPC);
// Note: actually, instruction address ranges of sequences should not
// overlap (in shared objects and executables). If they do, the address
// lookup would still work, though, but result would be ambiguous.
@ -919,31 +919,15 @@ uint32_t DWARFDebugLine::LineTable::lookupAddress(
uint32_t DWARFDebugLine::LineTable::lookupAddressImpl(
object::SectionedAddress Address) const {
if (Sequences.empty())
return UnknownRowIndex;
// First, find an instruction sequence containing the given address.
DWARFDebugLine::Sequence Sequence;
Sequence.SectionIndex = Address.SectionIndex;
Sequence.LowPC = Address.Address;
SequenceIter FirstSeq = Sequences.begin();
SequenceIter LastSeq = Sequences.end();
SequenceIter SeqPos = std::lower_bound(
FirstSeq, LastSeq, Sequence, DWARFDebugLine::Sequence::orderByLowPC);
DWARFDebugLine::Sequence FoundSeq;
if (SeqPos == LastSeq) {
FoundSeq = Sequences.back();
} else if (SeqPos->LowPC == Address.Address &&
SeqPos->SectionIndex == Address.SectionIndex) {
FoundSeq = *SeqPos;
} else {
if (SeqPos == FirstSeq)
return UnknownRowIndex;
FoundSeq = *(SeqPos - 1);
}
if (FoundSeq.SectionIndex != Address.SectionIndex)
Sequence.HighPC = Address.Address;
SequenceIter It = llvm::upper_bound(Sequences, Sequence,
DWARFDebugLine::Sequence::orderByHighPC);
if (It == Sequences.end() || It->SectionIndex != Address.SectionIndex)
return UnknownRowIndex;
return findRowInSeq(FoundSeq, Address);
return findRowInSeq(*It, Address);
}
bool DWARFDebugLine::LineTable::lookupAddressRange(
@ -971,17 +955,11 @@ bool DWARFDebugLine::LineTable::lookupAddressRangeImpl(
// First, find an instruction sequence containing the given address.
DWARFDebugLine::Sequence Sequence;
Sequence.SectionIndex = Address.SectionIndex;
Sequence.LowPC = Address.Address;
SequenceIter FirstSeq = Sequences.begin();
Sequence.HighPC = Address.Address;
SequenceIter LastSeq = Sequences.end();
SequenceIter SeqPos = std::lower_bound(
FirstSeq, LastSeq, Sequence, DWARFDebugLine::Sequence::orderByLowPC);
if (SeqPos == LastSeq || !SeqPos->containsPC(Address)) {
if (SeqPos == FirstSeq)
return false;
SeqPos--;
}
if (!SeqPos->containsPC(Address))
SequenceIter SeqPos = llvm::upper_bound(
Sequences, Sequence, DWARFDebugLine::Sequence::orderByHighPC);
if (SeqPos == LastSeq || !SeqPos->containsPC(Address))
return false;
SequenceIter StartPos = SeqPos;