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//===-- llvm-as-fuzzer.cpp - Fuzzer for llvm-as using lib/Fuzzer ----------===//
// 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
// Build tool to fuzz the LLVM assembler (llvm-as) using
// lib/Fuzzer. The main reason for using this tool is that it is much
// faster than using afl-fuzz, since it is run in-process.
#include "llvm/ADT/StringRef.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/raw_ostream.h"
#include <csetjmp>
using namespace llvm;
static jmp_buf JmpBuf;
namespace {
void MyFatalErrorHandler(void *user_data, const char *reason,
bool gen_crash_diag) {
// Don't bother printing reason, just return to the test function,
// since a fatal error represents a successful parse (i.e. it correctly
// terminated with an error message to the user).
longjmp(JmpBuf, 1);
static bool InstalledHandler = false;
} // end of anonymous namespace
extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
// Allocate space for locals before setjmp so that memory can be collected
// if parse exits prematurely (via longjmp).
StringRef Input((const char *)Data, Size);
// Note: We need to create a buffer to add a null terminator to the
// end of the input string. The parser assumes that the string
// parsed is always null terminated.
std::unique_ptr<MemoryBuffer> MemBuf = MemoryBuffer::getMemBufferCopy(Input);
SMDiagnostic Err;
LLVMContext Context;
std::unique_ptr<Module> M;
if (setjmp(JmpBuf))
// If reached, we have returned with non-zero status, so exit.
return 0;
// TODO(kschimpf) Write a main to do this initialization.
if (!InstalledHandler) {
llvm::install_fatal_error_handler(::MyFatalErrorHandler, nullptr);
InstalledHandler = true;
M = parseAssembly(MemBuf->getMemBufferRef(), Err, Context);
if (!M.get())
return 0;
if (verifyModule(*M.get(), &errs()))
report_fatal_error("Broken module");
return 0;