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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 =
M.getOrInsertFunction("klee_div_zero_check", Type::getVoidTy(ctx),
Type::getInt64Ty(ctx));
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) {
std::vector<llvm::BinaryOperator *> shiftInstructions;
for (auto &F : M) {
for (auto &BB : F) {
for (auto &I : BB) {
auto binOp = dyn_cast<BinaryOperator>(&I);
if (!binOp)
continue;
// find all shift instructions
auto opcode = binOp->getOpcode();
if (opcode != Instruction::Shl && opcode != Instruction::LShr &&
opcode != Instruction::AShr)
continue;
// Check if the operand is constant and not zero, skip in that case
auto operand = binOp->getOperand(1);
if (auto coOp = dyn_cast<llvm::ConstantInt>(operand)) {
auto typeWidth =
binOp->getOperand(0)->getType()->getScalarSizeInBits();
// If the constant shift is positive and smaller,equal the type width,
// we can ignore this instruction
if (!coOp->isNegative() && coOp->getZExtValue() < typeWidth)
continue;
}
if (KleeIRMetaData::hasAnnotation(I, "klee.check.shift", "True"))
continue;
shiftInstructions.push_back(binOp);
}
}
}
if (shiftInstructions.empty())
return false;
// Retrieve the checker function
auto &ctx = M.getContext();
KleeIRMetaData md(ctx);
auto overshiftCheckFunction = M.getOrInsertFunction(
"klee_overshift_check", Type::getVoidTy(ctx), Type::getInt64Ty(ctx),
Type::getInt64Ty(ctx));
for (auto &shiftInst : shiftInstructions) {
llvm::IRBuilder<> Builder(shiftInst);
std::vector<llvm::Value *> args;
// Determine bit width of first operand
uint64_t bitWidth = shiftInst->getOperand(0)->getType()->getScalarSizeInBits();
auto bitWidthC = ConstantInt::get(Type::getInt64Ty(ctx), bitWidth, false);
args.push_back(bitWidthC);
auto shiftValue =
Builder.CreateIntCast(shiftInst->getOperand(1), Type::getInt64Ty(ctx),
false, /* sign doesn't matter */
"int_cast_to_i64");
args.push_back(shiftValue);
Builder.CreateCall(overshiftCheckFunction, args);
md.addAnnotation(*shiftInst, "klee.check.shift", "True");
}
return true;
}
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