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| //==-- handle_llvm.cpp - Helper function for Clang fuzzers -----------------==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Implements HandleLLVM for use by the Clang fuzzers. First runs a loop
// vectorizer optimization pass over the given IR code. Then mimics lli on both
// versions to JIT the generated code and execute it. Currently, functions are
// executed on dummy inputs.
//
//===----------------------------------------------------------------------===//
#include "handle_llvm.h"
#include "input_arrays.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/CommandFlags.inc"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/ExecutionEngine/JITEventListener.h"
#include "llvm/ExecutionEngine/JITSymbol.h"
#include "llvm/ExecutionEngine/MCJIT.h"
#include "llvm/ExecutionEngine/ObjectCache.h"
#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
#include "llvm/ExecutionEngine/SectionMemoryManager.h"
#include "llvm/IR/IRPrintingPasses.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/LegacyPassNameParser.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/IRReader/IRReader.h"
#include "llvm/Pass.h"
#include "llvm/PassRegistry.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/Vectorize.h"
using namespace llvm;
// Define a type for the functions that are compiled and executed
typedef void (*LLVMFunc)(int*, int*, int*, int);
// Helper function to parse command line args and find the optimization level
static void getOptLevel(const std::vector<const char *> &ExtraArgs,
CodeGenOpt::Level &OLvl) {
// Find the optimization level from the command line args
OLvl = CodeGenOpt::Default;
for (auto &A : ExtraArgs) {
if (A[0] == '-' && A[1] == 'O') {
switch(A[2]) {
case '0': OLvl = CodeGenOpt::None; break;
case '1': OLvl = CodeGenOpt::Less; break;
case '2': OLvl = CodeGenOpt::Default; break;
case '3': OLvl = CodeGenOpt::Aggressive; break;
default:
errs() << "error: opt level must be between 0 and 3.\n";
std::exit(1);
}
}
}
}
static void ErrorAndExit(std::string message) {
errs()<< "ERROR: " << message << "\n";
std::exit(1);
}
// Helper function to add optimization passes to the TargetMachine at the
// specified optimization level, OptLevel
static void AddOptimizationPasses(legacy::PassManagerBase &MPM,
CodeGenOpt::Level OptLevel,
unsigned SizeLevel) {
// Create and initialize a PassManagerBuilder
PassManagerBuilder Builder;
Builder.OptLevel = OptLevel;
Builder.SizeLevel = SizeLevel;
Builder.Inliner = createFunctionInliningPass(OptLevel, SizeLevel, false);
Builder.LoopVectorize = true;
Builder.populateModulePassManager(MPM);
}
// Mimics the opt tool to run an optimization pass over the provided IR
static std::string OptLLVM(const std::string &IR, CodeGenOpt::Level OLvl) {
// Create a module that will run the optimization passes
SMDiagnostic Err;
LLVMContext Context;
std::unique_ptr<Module> M = parseIR(MemoryBufferRef(IR, "IR"), Err, Context);
if (!M || verifyModule(*M, &errs()))
ErrorAndExit("Could not parse IR");
Triple ModuleTriple(M->getTargetTriple());
const TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
std::string E;
const Target *TheTarget = TargetRegistry::lookupTarget(MArch, ModuleTriple, E);
TargetMachine *Machine =
TheTarget->createTargetMachine(M->getTargetTriple(), getCPUStr(),
getFeaturesStr(), Options, getRelocModel(),
getCodeModel(), OLvl);
std::unique_ptr<TargetMachine> TM(Machine);
setFunctionAttributes(getCPUStr(), getFeaturesStr(), *M);
legacy::PassManager Passes;
Passes.add(new TargetLibraryInfoWrapperPass(ModuleTriple));
Passes.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
LLVMTargetMachine <M = static_cast<LLVMTargetMachine &>(*TM);
Passes.add(LTM.createPassConfig(Passes));
Passes.add(createVerifierPass());
AddOptimizationPasses(Passes, OLvl, 0);
// Add a pass that writes the optimized IR to an output stream
std::string outString;
raw_string_ostream OS(outString);
Passes.add(createPrintModulePass(OS, "", false));
Passes.run(*M);
return OS.str();
}
// Takes a function and runs it on a set of inputs
// First determines whether f is the optimized or unoptimized function
static void RunFuncOnInputs(LLVMFunc f, int Arr[kNumArrays][kArraySize]) {
for (int i = 0; i < kNumArrays / 3; i++)
f(Arr[i], Arr[i + (kNumArrays / 3)], Arr[i + (2 * kNumArrays / 3)],
kArraySize);
}
// Takes a string of IR and compiles it using LLVM's JIT Engine
static void CreateAndRunJITFunc(const std::string &IR, CodeGenOpt::Level OLvl) {
SMDiagnostic Err;
LLVMContext Context;
std::unique_ptr<Module> M = parseIR(MemoryBufferRef(IR, "IR"), Err, Context);
if (!M)
ErrorAndExit("Could not parse IR");
Function *EntryFunc = M->getFunction("foo");
if (!EntryFunc)
ErrorAndExit("Function not found in module");
std::string ErrorMsg;
EngineBuilder builder(std::move(M));
builder.setMArch(MArch);
builder.setMCPU(getCPUStr());
builder.setMAttrs(getFeatureList());
builder.setErrorStr(&ErrorMsg);
builder.setEngineKind(EngineKind::JIT);
builder.setMCJITMemoryManager(std::make_unique<SectionMemoryManager>());
builder.setOptLevel(OLvl);
builder.setTargetOptions(InitTargetOptionsFromCodeGenFlags());
std::unique_ptr<ExecutionEngine> EE(builder.create());
if (!EE)
ErrorAndExit("Could not create execution engine");
EE->finalizeObject();
EE->runStaticConstructorsDestructors(false);
#if defined(__GNUC__) && !defined(__clang) && \
((__GNUC__ == 4) && (__GNUC_MINOR__ < 9))
// Silence
//
// warning: ISO C++ forbids casting between pointer-to-function and
// pointer-to-object [-Wpedantic]
//
// Since C++11 this casting is conditionally supported and GCC versions
// starting from 4.9.0 don't warn about the cast.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
#endif
LLVMFunc f = reinterpret_cast<LLVMFunc>(EE->getPointerToFunction(EntryFunc));
#if defined(__GNUC__) && !defined(__clang) && \
((__GNUC__ == 4) && (__GNUC_MINOR__ < 9))
#pragma GCC diagnostic pop
#endif
// Figure out if we are running the optimized func or the unoptimized func
RunFuncOnInputs(f, (OLvl == CodeGenOpt::None) ? UnoptArrays : OptArrays);
EE->runStaticConstructorsDestructors(true);
}
// Main fuzz target called by ExampleClangLLVMProtoFuzzer.cpp
// Mimics the lli tool to JIT the LLVM IR code and execute it
void clang_fuzzer::HandleLLVM(const std::string &IR,
const std::vector<const char *> &ExtraArgs) {
// Populate OptArrays and UnoptArrays with the arrays from InputArrays
memcpy(OptArrays, InputArrays, kTotalSize);
memcpy(UnoptArrays, InputArrays, kTotalSize);
// Parse ExtraArgs to set the optimization level
CodeGenOpt::Level OLvl;
getOptLevel(ExtraArgs, OLvl);
// First we optimize the IR by running a loop vectorizer pass
std::string OptIR = OptLLVM(IR, OLvl);
CreateAndRunJITFunc(OptIR, OLvl);
CreateAndRunJITFunc(IR, CodeGenOpt::None);
if (memcmp(OptArrays, UnoptArrays, kTotalSize))
ErrorAndExit("!!!BUG!!!");
return;
}
|