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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/STLExtras.h"
#include "llvm/ADT/SetVector.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/Object/ObjectFile.h"
#include "llvm/Support/MemoryObject.h"
#include "llvm/Support/StringRefMemoryObject.h"
#include "llvm/Support/raw_ostream.h"
#include <map>
#include <set>
using namespace llvm;
using namespace object;
MCObjectDisassembler::MCObjectDisassembler(const ObjectFile &Obj,
const MCDisassembler &Dis,
const MCInstrAnalysis &MIA)
: Obj(Obj), Dis(Dis), MIA(MIA) {}
MCModule *MCObjectDisassembler::buildModule(bool withCFG) {
MCModule *Module = new MCModule;
buildSectionAtoms(Module);
if (withCFG)
buildCFG(Module);
return Module;
}
void MCObjectDisassembler::buildSectionAtoms(MCModule *Module) {
error_code ec;
for (section_iterator SI = Obj.begin_sections(),
SE = Obj.end_sections();
SI != SE;
SI.increment(ec)) {
if (ec) break;
bool isText; SI->isText(isText);
bool isData; SI->isData(isData);
if (!isData && !isText)
continue;
uint64_t StartAddr; SI->getAddress(StartAddr);
uint64_t SecSize; SI->getSize(SecSize);
if (StartAddr == UnknownAddressOrSize || SecSize == UnknownAddressOrSize)
continue;
StringRef Contents; SI->getContents(Contents);
StringRefMemoryObject memoryObject(Contents);
// 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; SI->getName(SecName);
if (isText) {
MCTextAtom *Text = Module->createTextAtom(StartAddr, EndAddr);
Text->setName(SecName);
uint64_t InstSize;
for (uint64_t Index = 0; Index < SecSize; Index += InstSize) {
MCInst Inst;
if (Dis.getInstruction(Inst, InstSize, memoryObject, Index,
nulls(), nulls()))
Text->addInst(Inst, InstSize);
else
// We don't care about splitting mixed atoms either.
llvm_unreachable("Couldn't disassemble instruction in atom.");
}
} 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 std::set<BBInfo*> BBInfoSetTy;
struct BBInfo {
MCTextAtom *Atom;
MCBasicBlock *BB;
BBInfoSetTy Succs;
BBInfoSetTy Preds;
void addSucc(BBInfo &Succ) {
Succs.insert(&Succ);
Succ.Preds.insert(this);
}
};
}
void MCObjectDisassembler::buildCFG(MCModule *Module) {
typedef std::map<uint64_t, BBInfo> BBInfoByAddrTy;
BBInfoByAddrTy BBInfos;
typedef std::set<uint64_t> AddressSetTy;
AddressSetTy Splits;
AddressSetTy Calls;
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.insert(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.insert(II->Address + II->Size);
uint64_t Target;
if (MIA.evaluateBranch(II->Inst, II->Address, II->Size, Target)) {
if (MIA.isCall(II->Inst))
Calls.insert(Target);
Splits.insert(Target);
}
}
}
// 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)
MCBB->addSuccessor((*SI)->BB);
for (BBInfoSetTy::iterator PI = BBI->Preds.begin(), PE = BBI->Preds.end();
PI != PE; ++PI)
MCBB->addPredecessor((*PI)->BB);
}
}
}
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