C++ GetElementPtrInst::hasIndices方法代码示例

void Executor::executeGep(Instruction *i) {
    if (DisabledSymbolicExeCurRun) {
        return;
    }
    assert(i && "Expecting an instruction!");
    GetElementPtrInst *gep = (GetElementPtrInst*) i;
    assert(gep->getNumIndices()<=2 && "Unsupported gep instruction");
    if(AllocaInst *a = dyn_cast<AllocaInst>(gep->getPointerOperand())) {
        Type *ty = a->getAllocatedType();
        if (ty->isIntegerTy()) {
            // Incompleteness: pointer dereferencement on symbolic value
            AllLocDefinite = false;
            return;
        }
    }
    unsigned idx = 0;
    Type *subTy = NULL;
    Type *ptrOpTy = gep->getPointerOperandType();    
    if (ptrOpTy && ptrOpTy->getNumContainedTypes()==1) {
        subTy = ptrOpTy->getContainedType(0);
    }
    if (subTy && subTy->getNumContainedTypes()>0) {
        idx = 1;
    } else {
        assert("Unsupported gep instruction!");
    }
    Value *ptr = (Value*) i;
    if(gep->hasIndices()) {
        Value *index = gep->getOperand(idx+1);
        if (SMAP->contains(index)) {
            // P[v->sv] // sv is a new symbolic value
            // Value *a = gep->getPointerOperand();
            // ptr = (a index)  
            //SymbolPtr Sindex = SMAP->get(index);
            //PMAP->createGepOp(ptr, a, Sindex);
            
            // Incompleteness: pointer dereferencement on symbolic value
            AllLocDefinite = false;
        } else {
            // P = P - ptr
            PMAP->remove(ptr);
        }
    }
    // Global allocation
    /*else if(isa<GlobalVariable>(ptr)) {
        // ptr in domain(P)
        if (PMAP->contains(ptr)) {
            SymbolPtr Pptr = PMAP->get(ptr);
            // P' = P[ptr->S(val)]
            PMAP->update(ptr, Pptr);
        } else {
            // P = P - ptr
            PMAP->remove(ptr);
        }
    }*/
}

bool Aa::LowerGepPass::runOnFunction(Function &F)
{
  const llvm::Type *ptr_int_type = TD->getIntPtrType(F.getContext());

  for (Function::iterator bi = F.begin(), be = F.end(); bi != be; ++bi) {
    BasicBlock *bb = bi;

    BasicBlock::iterator ii = bb->begin();
    while (ii != bb->end()) {
      GetElementPtrInst *gep = dyn_cast<GetElementPtrInst>(ii);
      BasicBlock::iterator gi = ii++;
      if (!gep) {
	continue;
      }

      for (llvm::Value::use_iterator ui = gep->use_begin(), ue = gep->use_end();
           ui != ue; ++ui) {
        Use &u = ui.getUse();

        IOCode ioc = get_io_code(u);

        if (ioc == NOT_IO)
          continue;

        u.set(CastInst::CreatePointerCast(gep->getPointerOperand()
                                          , gep->getType()
                                          , "", gep));
      }

      assert(gep->hasIndices() && "GEP without indices??");
      llvm::Value *ptr = gep->getPointerOperand();
      const Type *ctype = ptr->getType();

      // deal with the base pointer first
      llvm::Value *base = gep->getPointerOperand();
      std::string base_name = gep->getNameStr() + ".base";
      llvm::Value *address = new PtrToIntInst(base, ptr_int_type, base_name + ".cast", gi);
      
      unsigned i = 0;
      for (User::op_iterator oi = gep->idx_begin(), oe = gep->idx_end();
	   oi != oe; ++oi, ++i) {
	llvm::Value *index = *oi;
	llvm::Value *offset = NULL;

	std::stringstream index_name;
	index_name << gep->getNameStr() << ".idx." << i;
	
	if (const SequentialType *qtype = dyn_cast<SequentialType>(ctype)) {
	  // multiply index by size of element

	  unsigned element_size = getTypePaddedSize(TD, qtype->getElementType());
	  const llvm::IntegerType *index_type = cast<IntegerType>(index->getType());
	  ConstantInt *cint = ConstantInt::get(index_type, element_size);
	  assert(cint && "uh oh!");
	  offset = BinaryOperator::Create(Instruction::Mul
					  , cint
					  , index
					  , index_name.str()
					  , gi);
	  ctype = qtype->getElementType();
	} else if (const StructType *stype = dyn_cast<StructType>(ctype)) {
	  // calculate offset into the struct

	  const StructLayout *layout = TD->getStructLayout(stype);
	  unsigned idx = cast<ConstantInt>(index)->getValue().getZExtValue();
	  unsigned struct_offset = layout->getElementOffset(idx);
	  offset = ConstantInt::get(ptr_int_type, struct_offset);
	  ctype = stype->getElementType(idx);
	} else
	  assert(false && "unhandled offset into composite type");
	
	// add offset to the address

	assert(address && "uh oh!");
	std::stringstream add_name;
	add_name << gep->getNameStr() << ".lvl." << i;
	
	if (offset->getType() != address->getType()) {
	  offset = CastInst::CreateIntegerCast(offset, address->getType()
					       , false, offset->getName() + ".resized"
					       , gi);
	}
	
	address = BinaryOperator::Create(Instruction::Add
					 , address, offset
					 , add_name.str(), gi);
      }

      if (address->getType() != ptr_int_type)
	address = CastInst::CreateIntegerCast(address, ptr_int_type
					      , false, address->getName() + ".final", gi);
      Instruction *new_ptr = new IntToPtrInst(address, gep->getType()
					  , gep->getName() + ".cast");
      ReplaceInstWithInst(bb->getInstList(), gi, new_ptr);
    }
  }

  return true;
}