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//===-- llvm-sim.cpp - Find similar sections of programs -------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This program finds similar sections of a Module, and exports them as a JSON
// file.
// To find similarities contained across multiple modules, please use llvm-link
// first to merge the modules.
#include "llvm/Analysis/IRSimilarityIdentifier.h"
#include "llvm/IRReader/IRReader.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/InitLLVM.h"
#include "llvm/Support/JSON.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/ToolOutputFile.h"
using namespace llvm;
using namespace IRSimilarity;
static cl::opt<std::string> OutputFilename("o", cl::desc("Output Filename"),
static cl::opt<std::string> InputSourceFile(cl::Positional,
cl::desc("<Source file>"),
/// Retrieve the unique number \p I was mapped to in parseBitcodeFile.
/// \param I - The Instruction to find the instruction number for.
/// \param LLVMInstNum - The mapping of Instructions to their location in the
/// module represented by an unsigned integer.
/// \returns The instruction number for \p I if it exists.
getPositionInModule(const Instruction *I,
const DenseMap<Instruction *, unsigned> &LLVMInstNum) {
assert(I && "Instruction is nullptr!");
DenseMap<Instruction *, unsigned>::const_iterator It = LLVMInstNum.find(I);
if (It == LLVMInstNum.end())
return None;
return It->second;
/// Exports the given SimilarityGroups to a JSON file at \p FilePath.
/// \param FilePath - The path to the output location.
/// \param SimSections - The similarity groups to process.
/// \param LLVMInstNum - The mapping of Instructions to their location in the
/// module represented by an unsigned integer.
/// \returns A nonzero error code if there was a failure creating the file.
exportToFile(const StringRef FilePath,
const SimilarityGroupList &SimSections,
const DenseMap<Instruction *, unsigned> &LLVMInstNum) {
std::error_code EC;
std::unique_ptr<ToolOutputFile> Out(
new ToolOutputFile(FilePath, EC, sys::fs::OF_None));
if (EC)
return EC;
json::OStream J(Out->os(), 1);
unsigned SimOption = 1;
// Process each list of SimilarityGroups organized by the Module.
for (const SimilarityGroup &G : SimSections) {
std::string SimOptionStr = std::to_string(SimOption);
// For each file there is a list of the range where the similarity
// exists.
for (const IRSimilarityCandidate &C : G) {
Optional<unsigned> Start =
getPositionInModule((*C.front()).Inst, LLVMInstNum);
Optional<unsigned> End =
getPositionInModule((*C.back()).Inst, LLVMInstNum);
assert(Start.hasValue() &&
"Could not find instruction number for first instruction");
assert(End.hasValue() &&
"Could not find instruction number for last instruction");
J.object([&] {
J.attribute("start", Start.getValue());
J.attribute("end", End.getValue());
return EC;
int main(int argc, const char *argv[]) {
InitLLVM X(argc, argv);
cl::ParseCommandLineOptions(argc, argv, "LLVM IR Similarity Visualizer\n");
LLVMContext CurrContext;
SMDiagnostic Err;
std::unique_ptr<Module> ModuleToAnalyze =
parseIRFile(InputSourceFile, Err, CurrContext);
if (!ModuleToAnalyze) {
Err.print(argv[0], errs());
return 1;
// Mapping from an Instruction pointer to its occurrence in a sequential
// list of all the Instructions in a Module.
DenseMap<Instruction *, unsigned> LLVMInstNum;
// We give each instruction a number, which gives us a start and end value
// for the beginning and end of each IRSimilarityCandidate.
unsigned InstructionNumber = 1;
for (Function &F : *ModuleToAnalyze)
for (BasicBlock &BB : F)
for (Instruction &I : BB.instructionsWithoutDebug())
LLVMInstNum[&I]= InstructionNumber++;
// The similarity identifier we will use to find the similar sections.
IRSimilarityIdentifier SimIdent;
SimilarityGroupList SimilaritySections =
std::error_code E =
exportToFile(OutputFilename, SimilaritySections, LLVMInstNum);
if (E) {
errs() << argv[0] << ": " << E.message() << '\n';
return 2;
return 0;