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llvm-mirror/lib/MC/MCObjectDisassembler.cpp
David Blaikie e2f6c1d28f Use unique_ptr to own MCFunctions within MCModule. 
MCModule's ctor had to be moved out of line so the definition of
MCFunction was available. (ctor requires the dtor of members (in case
the ctor throws) which required access to the dtor of MCFunction)

llvm-svn: 206244
2014-04-15 05:15:19 +00:00

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19 KiB
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//===- lib/MC/MCObjectDisassembler.cpp ------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCObjectDisassembler.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCAtom.h"
#include "llvm/MC/MCDisassembler.h"
#include "llvm/MC/MCFunction.h"
#include "llvm/MC/MCInstrAnalysis.h"
#include "llvm/MC/MCModule.h"
#include "llvm/MC/MCObjectSymbolizer.h"
#include "llvm/Object/MachO.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MachO.h"
#include "llvm/Support/MemoryObject.h"
#include "llvm/Support/StringRefMemoryObject.h"
#include "llvm/Support/raw_ostream.h"
#include <map>
using namespace llvm;
using namespace object;
MCObjectDisassembler::MCObjectDisassembler(const ObjectFile &Obj,
const MCDisassembler &Dis,
const MCInstrAnalysis &MIA)
: Obj(Obj), Dis(Dis), MIA(MIA), MOS(nullptr) {}
uint64_t MCObjectDisassembler::getEntrypoint() {
for (const SymbolRef &Symbol : Obj.symbols()) {
StringRef Name;
Symbol.getName(Name);
if (Name == "main" || Name == "_main") {
uint64_t Entrypoint;
Symbol.getAddress(Entrypoint);
return getEffectiveLoadAddr(Entrypoint);
}
}
return 0;
}
ArrayRef<uint64_t> MCObjectDisassembler::getStaticInitFunctions() {
return ArrayRef<uint64_t>();
}
ArrayRef<uint64_t> MCObjectDisassembler::getStaticExitFunctions() {
return ArrayRef<uint64_t>();
}
MemoryObject *MCObjectDisassembler::getRegionFor(uint64_t Addr) {
// FIXME: Keep track of object sections.
return FallbackRegion.get();
}
uint64_t MCObjectDisassembler::getEffectiveLoadAddr(uint64_t Addr) {
return Addr;
}
uint64_t MCObjectDisassembler::getOriginalLoadAddr(uint64_t Addr) {
return Addr;
}
MCModule *MCObjectDisassembler::buildEmptyModule() {
MCModule *Module = new MCModule;
Module->Entrypoint = getEntrypoint();
return Module;
}
MCModule *MCObjectDisassembler::buildModule(bool withCFG) {
MCModule *Module = buildEmptyModule();
buildSectionAtoms(Module);
if (withCFG)
buildCFG(Module);
return Module;
}
void MCObjectDisassembler::buildSectionAtoms(MCModule *Module) {
for (const SectionRef &Section : Obj.sections()) {
bool isText;
Section.isText(isText);
bool isData;
Section.isData(isData);
if (!isData && !isText)
continue;
uint64_t StartAddr;
Section.getAddress(StartAddr);
uint64_t SecSize;
Section.getSize(SecSize);
if (StartAddr == UnknownAddressOrSize || SecSize == UnknownAddressOrSize)
continue;
StartAddr = getEffectiveLoadAddr(StartAddr);
StringRef Contents;
Section.getContents(Contents);
StringRefMemoryObject memoryObject(Contents, StartAddr);
// We don't care about things like non-file-backed sections yet.
if (Contents.size() != SecSize || !SecSize)
continue;
uint64_t EndAddr = StartAddr + SecSize - 1;
StringRef SecName;
Section.getName(SecName);
if (isText) {
MCTextAtom *Text = nullptr;
MCDataAtom *InvalidData = nullptr;
uint64_t InstSize;
for (uint64_t Index = 0; Index < SecSize; Index += InstSize) {
const uint64_t CurAddr = StartAddr + Index;
MCInst Inst;
if (Dis.getInstruction(Inst, InstSize, memoryObject, CurAddr, nulls(),
nulls())) {
if (!Text) {
Text = Module->createTextAtom(CurAddr, CurAddr);
Text->setName(SecName);
}
Text->addInst(Inst, InstSize);
InvalidData = nullptr;
} else {
assert(InstSize && "getInstruction() consumed no bytes");
if (!InvalidData) {
Text = nullptr;
InvalidData = Module->createDataAtom(CurAddr, CurAddr+InstSize - 1);
}
for (uint64_t I = 0; I < InstSize; ++I)
InvalidData->addData(Contents[Index+I]);
}
}
} else {
MCDataAtom *Data = Module->createDataAtom(StartAddr, EndAddr);
Data->setName(SecName);
for (uint64_t Index = 0; Index < SecSize; ++Index)
Data->addData(Contents[Index]);
}
}
}
namespace {
struct BBInfo;
typedef SmallPtrSet<BBInfo*, 2> BBInfoSetTy;
struct BBInfo {
MCTextAtom *Atom;
MCBasicBlock *BB;
BBInfoSetTy Succs;
BBInfoSetTy Preds;
MCObjectDisassembler::AddressSetTy SuccAddrs;
BBInfo() : Atom(nullptr), BB(nullptr) {}
void addSucc(BBInfo &Succ) {
Succs.insert(&Succ);
Succ.Preds.insert(this);
}
};
}
static void RemoveDupsFromAddressVector(MCObjectDisassembler::AddressSetTy &V) {
std::sort(V.begin(), V.end());
V.erase(std::unique(V.begin(), V.end()), V.end());
}
void MCObjectDisassembler::buildCFG(MCModule *Module) {
typedef std::map<uint64_t, BBInfo> BBInfoByAddrTy;
BBInfoByAddrTy BBInfos;
AddressSetTy Splits;
AddressSetTy Calls;
for (const SymbolRef &Symbol : Obj.symbols()) {
SymbolRef::Type SymType;
Symbol.getType(SymType);
if (SymType == SymbolRef::ST_Function) {
uint64_t SymAddr;
Symbol.getAddress(SymAddr);
SymAddr = getEffectiveLoadAddr(SymAddr);
Calls.push_back(SymAddr);
Splits.push_back(SymAddr);
}
}
assert(Module->func_begin() == Module->func_end()
&& "Module already has a CFG!");
// First, determine the basic block boundaries and call targets.
for (MCModule::atom_iterator AI = Module->atom_begin(),
AE = Module->atom_end();
AI != AE; ++AI) {
MCTextAtom *TA = dyn_cast<MCTextAtom>(*AI);
if (!TA) continue;
Calls.push_back(TA->getBeginAddr());
BBInfos[TA->getBeginAddr()].Atom = TA;
for (MCTextAtom::const_iterator II = TA->begin(), IE = TA->end();
II != IE; ++II) {
if (MIA.isTerminator(II->Inst))
Splits.push_back(II->Address + II->Size);
uint64_t Target;
if (MIA.evaluateBranch(II->Inst, II->Address, II->Size, Target)) {
if (MIA.isCall(II->Inst))
Calls.push_back(Target);
Splits.push_back(Target);
}
}
}
RemoveDupsFromAddressVector(Splits);
RemoveDupsFromAddressVector(Calls);
// Split text atoms into basic block atoms.
for (AddressSetTy::const_iterator SI = Splits.begin(), SE = Splits.end();
SI != SE; ++SI) {
MCAtom *A = Module->findAtomContaining(*SI);
if (!A) continue;
MCTextAtom *TA = cast<MCTextAtom>(A);
if (TA->getBeginAddr() == *SI)
continue;
MCTextAtom *NewAtom = TA->split(*SI);
BBInfos[NewAtom->getBeginAddr()].Atom = NewAtom;
StringRef BBName = TA->getName();
BBName = BBName.substr(0, BBName.find_last_of(':'));
NewAtom->setName((BBName + ":" + utohexstr(*SI)).str());
}
// Compute succs/preds.
for (MCModule::atom_iterator AI = Module->atom_begin(),
AE = Module->atom_end();
AI != AE; ++AI) {
MCTextAtom *TA = dyn_cast<MCTextAtom>(*AI);
if (!TA) continue;
BBInfo &CurBB = BBInfos[TA->getBeginAddr()];
const MCDecodedInst &LI = TA->back();
if (MIA.isBranch(LI.Inst)) {
uint64_t Target;
if (MIA.evaluateBranch(LI.Inst, LI.Address, LI.Size, Target))
CurBB.addSucc(BBInfos[Target]);
if (MIA.isConditionalBranch(LI.Inst))
CurBB.addSucc(BBInfos[LI.Address + LI.Size]);
} else if (!MIA.isTerminator(LI.Inst))
CurBB.addSucc(BBInfos[LI.Address + LI.Size]);
}
// Create functions and basic blocks.
for (AddressSetTy::const_iterator CI = Calls.begin(), CE = Calls.end();
CI != CE; ++CI) {
BBInfo &BBI = BBInfos[*CI];
if (!BBI.Atom) continue;
MCFunction &MCFN = *Module->createFunction(BBI.Atom->getName());
// Create MCBBs.
SmallSetVector<BBInfo*, 16> Worklist;
Worklist.insert(&BBI);
for (size_t wi = 0; wi < Worklist.size(); ++wi) {
BBInfo *BBI = Worklist[wi];
if (!BBI->Atom)
continue;
BBI->BB = &MCFN.createBlock(*BBI->Atom);
// Add all predecessors and successors to the worklist.
for (BBInfoSetTy::iterator SI = BBI->Succs.begin(), SE = BBI->Succs.end();
SI != SE; ++SI)
Worklist.insert(*SI);
for (BBInfoSetTy::iterator PI = BBI->Preds.begin(), PE = BBI->Preds.end();
PI != PE; ++PI)
Worklist.insert(*PI);
}
// Set preds/succs.
for (size_t wi = 0; wi < Worklist.size(); ++wi) {
BBInfo *BBI = Worklist[wi];
MCBasicBlock *MCBB = BBI->BB;
if (!MCBB)
continue;
for (BBInfoSetTy::iterator SI = BBI->Succs.begin(), SE = BBI->Succs.end();
SI != SE; ++SI)
if ((*SI)->BB)
MCBB->addSuccessor((*SI)->BB);
for (BBInfoSetTy::iterator PI = BBI->Preds.begin(), PE = BBI->Preds.end();
PI != PE; ++PI)
if ((*PI)->BB)
MCBB->addPredecessor((*PI)->BB);
}
}
}
// Basic idea of the disassembly + discovery:
//
// start with the wanted address, insert it in the worklist
// while worklist not empty, take next address in the worklist:
// - check if atom exists there
// - if middle of atom:
// - split basic blocks referencing the atom
// - look for an already encountered BBInfo (using a map<atom, bbinfo>)
// - if there is, split it (new one, fallthrough, move succs, etc..)
// - if start of atom: nothing else to do
// - if no atom: create new atom and new bbinfo
// - look at the last instruction in the atom, add succs to worklist
// for all elements in the worklist:
// - create basic block, update preds/succs, etc..
//
MCBasicBlock *MCObjectDisassembler::getBBAt(MCModule *Module, MCFunction *MCFN,
uint64_t BBBeginAddr,
AddressSetTy &CallTargets,
AddressSetTy &TailCallTargets) {
typedef std::map<uint64_t, BBInfo> BBInfoByAddrTy;
typedef SmallSetVector<uint64_t, 16> AddrWorklistTy;
BBInfoByAddrTy BBInfos;
AddrWorklistTy Worklist;
Worklist.insert(BBBeginAddr);
for (size_t wi = 0; wi < Worklist.size(); ++wi) {
const uint64_t BeginAddr = Worklist[wi];
BBInfo *BBI = &BBInfos[BeginAddr];
MCTextAtom *&TA = BBI->Atom;
assert(!TA && "Discovered basic block already has an associated atom!");
// Look for an atom at BeginAddr.
if (MCAtom *A = Module->findAtomContaining(BeginAddr)) {
// FIXME: We don't care about mixed atoms, see above.
TA = cast<MCTextAtom>(A);
// The found atom doesn't begin at BeginAddr, we have to split it.
if (TA->getBeginAddr() != BeginAddr) {
// FIXME: Handle overlapping atoms: middle-starting instructions, etc..
MCTextAtom *NewTA = TA->split(BeginAddr);
// Look for an already encountered basic block that needs splitting
BBInfoByAddrTy::iterator It = BBInfos.find(TA->getBeginAddr());
if (It != BBInfos.end() && It->second.Atom) {
BBI->SuccAddrs = It->second.SuccAddrs;
It->second.SuccAddrs.clear();
It->second.SuccAddrs.push_back(BeginAddr);
}
TA = NewTA;
}
BBI->Atom = TA;
} else {
// If we didn't find an atom, then we have to disassemble to create one!
MemoryObject *Region = getRegionFor(BeginAddr);
if (!Region)
llvm_unreachable(("Couldn't find suitable region for disassembly at " +
utostr(BeginAddr)).c_str());
uint64_t InstSize;
uint64_t EndAddr = Region->getBase() + Region->getExtent();
// We want to stop before the next atom and have a fallthrough to it.
if (MCTextAtom *NextAtom =
cast_or_null<MCTextAtom>(Module->findFirstAtomAfter(BeginAddr)))
EndAddr = std::min(EndAddr, NextAtom->getBeginAddr());
for (uint64_t Addr = BeginAddr; Addr < EndAddr; Addr += InstSize) {
MCInst Inst;
if (Dis.getInstruction(Inst, InstSize, *Region, Addr, nulls(),
nulls())) {
if (!TA)
TA = Module->createTextAtom(Addr, Addr);
TA->addInst(Inst, InstSize);
} else {
// We don't care about splitting mixed atoms either.
llvm_unreachable("Couldn't disassemble instruction in atom.");
}
uint64_t BranchTarget;
if (MIA.evaluateBranch(Inst, Addr, InstSize, BranchTarget)) {
if (MIA.isCall(Inst))
CallTargets.push_back(BranchTarget);
}
if (MIA.isTerminator(Inst))
break;
}
BBI->Atom = TA;
}
assert(TA && "Couldn't disassemble atom, none was created!");
assert(TA->begin() != TA->end() && "Empty atom!");
MemoryObject *Region = getRegionFor(TA->getBeginAddr());
assert(Region && "Couldn't find region for already disassembled code!");
uint64_t EndRegion = Region->getBase() + Region->getExtent();
// Now we have a basic block atom, add successors.
// Add the fallthrough block.
if ((MIA.isConditionalBranch(TA->back().Inst) ||
!MIA.isTerminator(TA->back().Inst)) &&
(TA->getEndAddr() + 1 < EndRegion)) {
BBI->SuccAddrs.push_back(TA->getEndAddr() + 1);
Worklist.insert(TA->getEndAddr() + 1);
}
// If the terminator is a branch, add the target block.
if (MIA.isBranch(TA->back().Inst)) {
uint64_t BranchTarget;
if (MIA.evaluateBranch(TA->back().Inst, TA->back().Address,
TA->back().Size, BranchTarget)) {
StringRef ExtFnName;
if (MOS)
ExtFnName =
MOS->findExternalFunctionAt(getOriginalLoadAddr(BranchTarget));
if (!ExtFnName.empty()) {
TailCallTargets.push_back(BranchTarget);
CallTargets.push_back(BranchTarget);
} else {
BBI->SuccAddrs.push_back(BranchTarget);
Worklist.insert(BranchTarget);
}
}
}
}
for (size_t wi = 0, we = Worklist.size(); wi != we; ++wi) {
const uint64_t BeginAddr = Worklist[wi];
BBInfo *BBI = &BBInfos[BeginAddr];
assert(BBI->Atom && "Found a basic block without an associated atom!");
// Look for a basic block at BeginAddr.
BBI->BB = MCFN->find(BeginAddr);
if (BBI->BB) {
// FIXME: check that the succs/preds are the same
continue;
}
// If there was none, we have to create one from the atom.
BBI->BB = &MCFN->createBlock(*BBI->Atom);
}
for (size_t wi = 0, we = Worklist.size(); wi != we; ++wi) {
const uint64_t BeginAddr = Worklist[wi];
BBInfo *BBI = &BBInfos[BeginAddr];
MCBasicBlock *BB = BBI->BB;
RemoveDupsFromAddressVector(BBI->SuccAddrs);
for (AddressSetTy::const_iterator SI = BBI->SuccAddrs.begin(),
SE = BBI->SuccAddrs.end();
SE != SE; ++SI) {
MCBasicBlock *Succ = BBInfos[*SI].BB;
BB->addSuccessor(Succ);
Succ->addPredecessor(BB);
}
}
assert(BBInfos[Worklist[0]].BB &&
"No basic block created at requested address?");
return BBInfos[Worklist[0]].BB;
}
MCFunction *
MCObjectDisassembler::createFunction(MCModule *Module, uint64_t BeginAddr,
AddressSetTy &CallTargets,
AddressSetTy &TailCallTargets) {
// First, check if this is an external function.
StringRef ExtFnName;
if (MOS)
ExtFnName = MOS->findExternalFunctionAt(getOriginalLoadAddr(BeginAddr));
if (!ExtFnName.empty())
return Module->createFunction(ExtFnName);
// If it's not, look for an existing function.
for (MCModule::func_iterator FI = Module->func_begin(),
FE = Module->func_end();
FI != FE; ++FI) {
if ((*FI)->empty())
continue;
// FIXME: MCModule should provide a findFunctionByAddr()
if ((*FI)->getEntryBlock()->getInsts()->getBeginAddr() == BeginAddr)
return FI->get();
}
// Finally, just create a new one.
MCFunction *MCFN = Module->createFunction("");
getBBAt(Module, MCFN, BeginAddr, CallTargets, TailCallTargets);
return MCFN;
}
// MachO MCObjectDisassembler implementation.
MCMachOObjectDisassembler::MCMachOObjectDisassembler(
const MachOObjectFile &MOOF, const MCDisassembler &Dis,
const MCInstrAnalysis &MIA, uint64_t VMAddrSlide,
uint64_t HeaderLoadAddress)
: MCObjectDisassembler(MOOF, Dis, MIA), MOOF(MOOF),
VMAddrSlide(VMAddrSlide), HeaderLoadAddress(HeaderLoadAddress) {
for (const SectionRef &Section : MOOF.sections()) {
StringRef Name;
Section.getName(Name);
// FIXME: We should use the S_ section type instead of the name.
if (Name == "__mod_init_func") {
DEBUG(dbgs() << "Found __mod_init_func section!\n");
Section.getContents(ModInitContents);
} else if (Name == "__mod_exit_func") {
DEBUG(dbgs() << "Found __mod_exit_func section!\n");
Section.getContents(ModExitContents);
}
}
}
// FIXME: Only do the translations for addresses actually inside the object.
uint64_t MCMachOObjectDisassembler::getEffectiveLoadAddr(uint64_t Addr) {
return Addr + VMAddrSlide;
}
uint64_t
MCMachOObjectDisassembler::getOriginalLoadAddr(uint64_t EffectiveAddr) {
return EffectiveAddr - VMAddrSlide;
}
uint64_t MCMachOObjectDisassembler::getEntrypoint() {
uint64_t EntryFileOffset = 0;
// Look for LC_MAIN.
{
uint32_t LoadCommandCount = MOOF.getHeader().ncmds;
MachOObjectFile::LoadCommandInfo Load = MOOF.getFirstLoadCommandInfo();
for (unsigned I = 0;; ++I) {
if (Load.C.cmd == MachO::LC_MAIN) {
EntryFileOffset =
((const MachO::entry_point_command *)Load.Ptr)->entryoff;
break;
}
if (I == LoadCommandCount - 1)
break;
else
Load = MOOF.getNextLoadCommandInfo(Load);
}
}
// If we didn't find anything, default to the common implementation.
// FIXME: Maybe we could also look at LC_UNIXTHREAD and friends?
if (EntryFileOffset)
return MCObjectDisassembler::getEntrypoint();
return EntryFileOffset + HeaderLoadAddress;
}
ArrayRef<uint64_t> MCMachOObjectDisassembler::getStaticInitFunctions() {
// FIXME: We only handle 64bit mach-o
assert(MOOF.is64Bit());
size_t EntrySize = 8;
size_t EntryCount = ModInitContents.size() / EntrySize;
return ArrayRef<uint64_t>(
reinterpret_cast<const uint64_t *>(ModInitContents.data()), EntryCount);
}
ArrayRef<uint64_t> MCMachOObjectDisassembler::getStaticExitFunctions() {
// FIXME: We only handle 64bit mach-o
assert(MOOF.is64Bit());
size_t EntrySize = 8;
size_t EntryCount = ModExitContents.size() / EntrySize;
return ArrayRef<uint64_t>(
reinterpret_cast<const uint64_t *>(ModExitContents.data()), EntryCount);
}
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