std::vector<std::pair<SymbolRef, uint64_t>>
llvm::object::computeSymbolSizes(const ObjectFile &O) {
std::vector<std::pair<SymbolRef, uint64_t>> Ret;
if (const auto *E = dyn_cast<ELFObjectFileBase>(&O)) {
auto Syms = E->symbols();
if (Syms.begin() == Syms.end())
Syms = E->getDynamicSymbolIterators();
for (ELFSymbolRef Sym : Syms)
Ret.push_back({Sym, Sym.getSize()});
return Ret;
}
// Collect sorted symbol addresses. Include dummy addresses for the end
// of each section.
std::vector<SymEntry> Addresses;
unsigned SymNum = 0;
for (symbol_iterator I = O.symbol_begin(), E = O.symbol_end(); I != E; ++I) {
SymbolRef Sym = *I;
uint64_t Value = Sym.getValue();
Addresses.push_back({I, Value, SymNum, getSymbolSectionID(O, Sym)});
++SymNum;
}
for (SectionRef Sec : O.sections()) {
uint64_t Address = Sec.getAddress();
uint64_t Size = Sec.getSize();
Addresses.push_back(
{O.symbol_end(), Address + Size, 0, getSectionID(O, Sec)});
}
array_pod_sort(Addresses.begin(), Addresses.end(), compareAddress);
// Compute the size as the gap to the next symbol
for (unsigned I = 0, N = Addresses.size() - 1; I < N; ++I) {
auto &P = Addresses[I];
if (P.I == O.symbol_end())
continue;
// If multiple symbol have the same address, give both the same size.
unsigned NextI = I + 1;
while (NextI < N && Addresses[NextI].Address == P.Address)
++NextI;
uint64_t Size = Addresses[NextI].Address - P.Address;
P.Address = Size;
}
// Assign the sorted symbols in the original order.
Ret.resize(SymNum);
for (SymEntry &P : Addresses) {
if (P.I == O.symbol_end())
continue;
Ret[P.Number] = {*P.I, P.Address};
}
return Ret;
}
// Compute an upper bound of the memory size that is required to load all
// sections
void RuntimeDyldImpl::computeTotalAllocSize(const ObjectFile &Obj,
uint64_t &CodeSize,
uint64_t &DataSizeRO,
uint64_t &DataSizeRW) {
// Compute the size of all sections required for execution
std::vector<uint64_t> CodeSectionSizes;
std::vector<uint64_t> ROSectionSizes;
std::vector<uint64_t> RWSectionSizes;
uint64_t MaxAlignment = sizeof(void *);
// Collect sizes of all sections to be loaded;
// also determine the max alignment of all sections
for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
SI != SE; ++SI) {
const SectionRef &Section = *SI;
bool IsRequired = Section.isRequiredForExecution();
// Consider only the sections that are required to be loaded for execution
if (IsRequired) {
StringRef Name;
uint64_t DataSize = Section.getSize();
uint64_t Alignment64 = Section.getAlignment();
bool IsCode = Section.isText();
bool IsReadOnly = Section.isReadOnlyData();
Check(Section.getName(Name));
unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
uint64_t StubBufSize = computeSectionStubBufSize(Obj, Section);
uint64_t SectionSize = DataSize + StubBufSize;
// The .eh_frame section (at least on Linux) needs an extra four bytes
// padded
// with zeroes added at the end. For MachO objects, this section has a
// slightly different name, so this won't have any effect for MachO
// objects.
if (Name == ".eh_frame")
SectionSize += 4;
if (SectionSize > 0) {
// save the total size of the section
if (IsCode) {
CodeSectionSizes.push_back(SectionSize);
} else if (IsReadOnly) {
ROSectionSizes.push_back(SectionSize);
} else {
RWSectionSizes.push_back(SectionSize);
}
// update the max alignment
if (Alignment > MaxAlignment) {
MaxAlignment = Alignment;
}
}
}
}
// Compute the size of all common symbols
uint64_t CommonSize = 0;
for (symbol_iterator I = Obj.symbol_begin(), E = Obj.symbol_end(); I != E;
++I) {
uint32_t Flags = I->getFlags();
if (Flags & SymbolRef::SF_Common) {
// Add the common symbols to a list. We'll allocate them all below.
uint64_t Size = 0;
Check(I->getSize(Size));
CommonSize += Size;
}
}
if (CommonSize != 0) {
RWSectionSizes.push_back(CommonSize);
}
// Compute the required allocation space for each different type of sections
// (code, read-only data, read-write data) assuming that all sections are
// allocated with the max alignment. Note that we cannot compute with the
// individual alignments of the sections, because then the required size
// depends on the order, in which the sections are allocated.
CodeSize = computeAllocationSizeForSections(CodeSectionSizes, MaxAlignment);
DataSizeRO = computeAllocationSizeForSections(ROSectionSizes, MaxAlignment);
DataSizeRW = computeAllocationSizeForSections(RWSectionSizes, MaxAlignment);
}
