void Lint::visitIndirectBrInst(IndirectBrInst &I) {
visitMemoryReference(I, I.getAddress(), MemoryLocation::UnknownSize, 0,
nullptr, MemRef::Branchee);
Assert(I.getNumDestinations() != 0,
"Undefined behavior: indirectbr with no destinations", &I);
}
void LLVM_General_GetIndirectBrDests(
LLVMValueRef v,
LLVMBasicBlockRef *dests
) {
IndirectBrInst *ib = unwrap<IndirectBrInst>(v);
for(unsigned i=0; i != ib->getNumDestinations(); ++i, ++dests)
*dests = wrap(ib->getDestination(i));
}
void Lint::visitIndirectBrInst(IndirectBrInst &I) {
visitMemoryReference(I, I.getAddress(), ~0u, 0, 0, MemRef::Branchee);
}
void Lint::visitIndirectBrInst(IndirectBrInst &I) {
visitMemoryReference(I, I.getAddress(), 0, 0);
}
bool runOnFunction(Function &Func) override {
if (Func.isDeclaration()) {
return false;
}
vector<BranchInst *> BIs;
for (inst_iterator I = inst_begin(Func); I != inst_end(Func); I++) {
Instruction *Inst = &(*I);
if (BranchInst *BI = dyn_cast<BranchInst>(Inst)) {
BIs.push_back(BI);
}
} // Finish collecting branching conditions
Value *zero =
ConstantInt::get(Type::getInt32Ty(Func.getParent()->getContext()), 0);
for (BranchInst *BI : BIs) {
IRBuilder<> IRB(BI);
vector<BasicBlock *> BBs;
// We use the condition's evaluation result to generate the GEP
// instruction False evaluates to 0 while true evaluates to 1. So here
// we insert the false block first
if (BI->isConditional()) {
BBs.push_back(BI->getSuccessor(1));
}
BBs.push_back(BI->getSuccessor(0));
ArrayType *AT = ArrayType::get(
Type::getInt8PtrTy(Func.getParent()->getContext()), BBs.size());
vector<Constant *> BlockAddresses;
for (unsigned i = 0; i < BBs.size(); i++) {
BlockAddresses.push_back(BlockAddress::get(BBs[i]));
}
GlobalVariable *LoadFrom = NULL;
if (BI->isConditional() || indexmap.find(BI->getSuccessor(0))==indexmap.end()) {
// Create a new GV
Constant *BlockAddressArray =
ConstantArray::get(AT, ArrayRef<Constant *>(BlockAddresses));
LoadFrom = new GlobalVariable(*Func.getParent(), AT, false,
GlobalValue::LinkageTypes::PrivateLinkage,
BlockAddressArray);
} else {
LoadFrom =
Func.getParent()->getGlobalVariable("IndirectBranchingGlobalTable",true);
}
Value *index = NULL;
if (BI->isConditional()) {
Value *condition = BI->getCondition();
index = IRB.CreateZExt(
condition, Type::getInt32Ty(Func.getParent()->getContext()));
} else {
index =
ConstantInt::get(Type::getInt32Ty(Func.getParent()->getContext()),
indexmap[BI->getSuccessor(0)]);
}
Value *GEP = IRB.CreateGEP(LoadFrom, {zero, index});
LoadInst *LI = IRB.CreateLoad(GEP, "IndirectBranchingTargetAddress");
IndirectBrInst *indirBr = IndirectBrInst::Create(LI, BBs.size());
for (BasicBlock *BB : BBs) {
indirBr->addDestination(BB);
}
ReplaceInstWithInst(BI, indirBr);
}
return true;
}
