llvm/lib/Object/SymbolSize.cpp
Kuba Brecka 4a7eeb4052 Fix llvm-symbolizer to correctly sort a symbol array and calculate symbol sizes
Sometimes, llvm-symbolizer gives wrong results due to incorrect sizes of some symbols. The reason for that was an incorrectly sorted array in computeSymbolSizes. The comparison function used subtraction of unsigned types, which is incorrect. Let's change this to return explicit -1 or 1.

Differential Revision: https://reviews.llvm.org/D26537



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287028 91177308-0d34-0410-b5e6-96231b3b80d8
2016-11-15 21:07:03 +00:00

95 lines
3.0 KiB
C++

//===- SymbolSize.cpp -----------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Object/SymbolSize.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Object/COFF.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/MachO.h"
using namespace llvm;
using namespace object;
// Orders increasingly by (SectionID, Address).
int llvm::object::compareAddress(const SymEntry *A, const SymEntry *B) {
if (A->SectionID != B->SectionID)
return A->SectionID < B->SectionID ? -1 : 1;
if (A->Address != B->Address)
return A->Address < B->Address ? -1 : 1;
return 0;
}
static unsigned getSectionID(const ObjectFile &O, SectionRef Sec) {
if (auto *M = dyn_cast<MachOObjectFile>(&O))
return M->getSectionID(Sec);
return cast<COFFObjectFile>(O).getSectionID(Sec);
}
static unsigned getSymbolSectionID(const ObjectFile &O, SymbolRef Sym) {
if (auto *M = dyn_cast<MachOObjectFile>(&O))
return M->getSymbolSectionID(Sym);
return cast<COFFObjectFile>(O).getSymbolSectionID(Sym);
}
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;
}