bool operator()(const Fragment& a, const Fragment& b) {
ARMExSectionTuple* tupleA = m_ExData.getTupleByExIdx(&a);
ARMExSectionTuple* tupleB = m_ExData.getTupleByExIdx(&b);
Fragment* textFragA = tupleA->getTextFragment();
Fragment* textFragB = tupleB->getTextFragment();
uint64_t addrA = textFragA->getParent()->getSection().addr() +
textFragA->getOffset();
uint64_t addrB = textFragB->getParent()->getSection().addr() +
textFragB->getOffset();
return (addrA < addrB);
}
void ARMGNULDBackend::rewriteARMExIdxSection(Module& pModule) {
if (!m_pEXIDX->hasSectionData()) {
// Return if this is empty section.
return;
}
SectionData* sectData = m_pEXIDX->getSectionData();
SectionData::FragmentListType& list = sectData->getFragmentList();
// Move the first fragment (align fragment) and last fragment (null fragment)
// to temporary list because we would only like to sort the region fragment.
SectionData::FragmentListType tmp;
{
SectionData::iterator first = sectData->begin();
SectionData::iterator last = sectData->end();
--last;
assert(first->getKind() == Fragment::Alignment);
assert(last->getKind() == Fragment::Null);
tmp.splice(tmp.end(), list, first);
tmp.splice(tmp.end(), list, last);
}
// Sort the region fragments in the .ARM.exidx output section.
sort(list, ExIdxFragmentComparator(m_ExData));
// Fix the coverage of the .ARM.exidx table.
llvm::StringRef cantUnwindRegion(g_CantUnwindEntry,
sizeof(g_CantUnwindEntry));
SectionData::FragmentListType::iterator it = list.begin();
if (it != list.end()) {
Fragment* prevTextFrag = m_ExData.getTupleByExIdx(it)->getTextFragment();
uint64_t prevTextEnd = prevTextFrag->getParent()->getSection().addr() +
prevTextFrag->getOffset() +
prevTextFrag->size();
++it;
while (it != list.end()) {
Fragment* currTextFrag = m_ExData.getTupleByExIdx(it)->getTextFragment();
uint64_t currTextBegin = currTextFrag->getParent()->getSection().addr() +
currTextFrag->getOffset();
if (currTextBegin > prevTextEnd) {
// Found a gap. Insert a can't unwind entry.
RegionFragment* frag = new RegionFragment(cantUnwindRegion, nullptr);
frag->setParent(sectData);
list.insert(it, frag);
// Add PREL31 reference to the beginning of the uncovered region.
Relocation* reloc =
Relocation::Create(static_cast<uint32_t>(llvm::ELF::R_ARM_PREL31),
*FragmentRef::Create(*frag, /* pOffset */0),
/* pAddend */0);
reloc->setSymInfo(
CreateLocalSymbolToFragmentEnd(pModule, *prevTextFrag));
addExtraRelocation(reloc);
}
prevTextEnd = currTextBegin + currTextFrag->size();
prevTextFrag = currTextFrag;
++it;
}
// Add a can't unwind entry to terminate .ARM.exidx section.
RegionFragment* frag = new RegionFragment(cantUnwindRegion, nullptr);
frag->setParent(sectData);
list.push_back(frag);
// Add PREL31 reference to the end of the .text section.
Relocation* reloc =
Relocation::Create(static_cast<uint32_t>(llvm::ELF::R_ARM_PREL31),
*FragmentRef::Create(*frag, /* pOffset */0),
/* pAddend */0);
reloc->setSymInfo(CreateLocalSymbolToFragmentEnd(pModule, *prevTextFrag));
addExtraRelocation(reloc);
}
// Add the first and the last fragment back.
list.splice(list.begin(), tmp, tmp.begin());
list.splice(list.end(), tmp, tmp.begin());
// Update the fragment offsets.
uint64_t offset = 0;
for (SectionData::iterator it = sectData->begin(), end = sectData->end();
it != end; ++it) {
it->setOffset(offset);
offset += it->size();
}
// Update the section size.
m_pEXIDX->setSize(offset);
// Rebuild the section header.
setOutputSectionAddress(pModule);
}
