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//===-- Checks.cpp --------------------------------------------------------===//
//
// The KLEE Symbolic Virtual Machine
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "Passes.h"
#include "klee/Config/Version.h"
#include "KLEEIRMetaData.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
using namespace llvm;
using namespace klee;
char DivCheckPass::ID;
bool DivCheckPass::runOnModule(Module &M) {
std::vector<llvm::BinaryOperator *> divInstruction;
for (auto &F : M) {
for (auto &BB : F) {
for (auto &I : BB) {
auto binOp = dyn_cast<BinaryOperator>(&I);
if (!binOp)
continue;
// find all [s|u][div|rem] instructions
auto opcode = binOp->getOpcode();
if (opcode != Instruction::SDiv && opcode != Instruction::UDiv &&
opcode != Instruction::SRem && opcode != Instruction::URem)
continue;
// Check if the operand is constant and not zero, skip in that case.
const auto &operand = binOp->getOperand(1);
if (const auto &coOp = dyn_cast<llvm::Constant>(operand)) {
if (!coOp->isZeroValue())
continue;
}
// Check if the operand is already checked by "klee_div_zero_check"
if (KleeIRMetaData::hasAnnotation(I, "klee.check.div", "True"))
continue;
divInstruction.push_back(binOp);
}
}
}
// If nothing to do, return
if (divInstruction.empty())
return false;
LLVMContext &ctx = M.getContext();
KleeIRMetaData md(ctx);
auto divZeroCheckFunction = cast<Function>(
M.getOrInsertFunction("klee_div_zero_check", Type::getVoidTy(ctx),
Type::getInt64Ty(ctx), NULL));
for (auto &divInst : divInstruction) {
llvm::IRBuilder<> Builder(divInst /* Inserts before divInst*/);
auto denominator =
Builder.CreateIntCast(divInst->getOperand(1), Type::getInt64Ty(ctx),
false, /* sign doesn't matter */
"int_cast_to_i64");
Builder.CreateCall(divZeroCheckFunction, denominator);
md.addAnnotation(*divInst, "klee.check.div", "True");
}
return true;
}
char OvershiftCheckPass::ID;
bool OvershiftCheckPass::runOnModule(Module &M) {
Function *overshiftCheckFunction = 0;
LLVMContext &ctx = M.getContext();
bool moduleChanged = false;
for (Module::iterator f = M.begin(), fe = M.end(); f != fe; ++f) {
for (Function::iterator b = f->begin(), be = f->end(); b != be; ++b) {
for (BasicBlock::iterator i = b->begin(), ie = b->end(); i != ie; ++i) {
if (BinaryOperator* binOp = dyn_cast<BinaryOperator>(i)) {
// find all shift instructions
Instruction::BinaryOps opcode = binOp->getOpcode();
if (opcode == Instruction::Shl ||
opcode == Instruction::LShr ||
opcode == Instruction::AShr ) {
std::vector<llvm::Value*> args;
// Determine bit width of first operand
uint64_t bitWidth=i->getOperand(0)->getType()->getScalarSizeInBits();
ConstantInt *bitWidthC = ConstantInt::get(Type::getInt64Ty(ctx),
bitWidth, false);
args.push_back(bitWidthC);
CastInst *shift =
CastInst::CreateIntegerCast(i->getOperand(1),
Type::getInt64Ty(ctx),
false, /* sign doesn't matter */
"int_cast_to_i64",
&*i);
args.push_back(shift);
// Lazily bind the function to avoid always importing it.
if (!overshiftCheckFunction) {
Constant *fc = M.getOrInsertFunction("klee_overshift_check",
Type::getVoidTy(ctx),
Type::getInt64Ty(ctx),
Type::getInt64Ty(ctx),
NULL);
overshiftCheckFunction = cast<Function>(fc);
}
// Inject CallInstr to check if overshifting possible
CallInst *ci =
CallInst::Create(overshiftCheckFunction, args, "", &*i);
// set debug information from binary operand to preserve it
ci->setDebugLoc(binOp->getDebugLoc());
moduleChanged = true;
}
}
}
}
}
return moduleChanged;
}
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