text: /*
   * Copyright (c) 2015 PLUMgrid, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  #include <algorithm>
  #include <fcntl.h>
  #include <ftw.h>
  #include <map>
  #include <stdio.h>
  #include <string>
  #include <sys/stat.h>
  #include <sys/utsname.h>
  #include <unistd.h>
  #include <vector>
  #include <linux/bpf.h>
  
  #include <llvm/ADT/STLExtras.h>
  #include <llvm/ExecutionEngine/MCJIT.h>
  #include <llvm/ExecutionEngine/SectionMemoryManager.h>
  #include <llvm/IRReader/IRReader.h>
  #include <llvm/IR/IRBuilder.h>
  #include <llvm/IR/IRPrintingPasses.h>
  #include <llvm/IR/LegacyPassManager.h>
  #include <llvm/IR/LLVMContext.h>
  #include <llvm/IR/Module.h>
  #include <llvm/IR/Verifier.h>
  #include <llvm/Object/ObjectFile.h>
  #include <llvm/Support/FormattedStream.h>
  #include <llvm/Support/Host.h>
  #include <llvm/Support/SourceMgr.h>
  #include <llvm/Support/TargetSelect.h>
  #include <llvm/Transforms/IPO.h>
  #include <llvm/Transforms/IPO/PassManagerBuilder.h>
  #include <llvm-c/Transforms/IPO.h>
  
  #include "common.h"
  #include "bcc_debug.h"
  #include "bcc_exception.h"
  #include "frontends/b/loader.h"
  #include "frontends/clang/loader.h"
  #include "frontends/clang/b_frontend_action.h"
  #include "bpf_module.h"
  #include "exported_files.h"
  #include "kbuild_helper.h"
  #include "libbpf.h"
  
  namespace ebpf {
  
  using std::get;
  using std::make_tuple;
  using std::map;
  using std::move;
  using std::string;
  using std::tuple;
  using std::unique_ptr;
  using std::vector;
  using namespace llvm;
  
  const string BPFModule::FN_PREFIX = BPF_FN_PREFIX;
  
  // Snooping class to remember the sections as the JIT creates them
  class MyMemoryManager : public SectionMemoryManager {
   public:
  
    explicit MyMemoryManager(map<string, tuple<uint8_t *, uintptr_t>> *sections)
        : sections_(sections) {
    }
  
    virtual ~MyMemoryManager() {}
    uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
                                 unsigned SectionID,
                                 StringRef SectionName) override {
      uint8_t *Addr = SectionMemoryManager::allocateCodeSection(Size, Alignment, SectionID, SectionName);
      //printf("allocateCodeSection: %s Addr %p Size %ld Alignment %d SectionID %d\n",
      //       SectionName.str().c_str(), (void *)Addr, Size, Alignment, SectionID);
      (*sections_)[SectionName.str()] = make_tuple(Addr, Size);
      return Addr;
    }
    uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
                                 unsigned SectionID, StringRef SectionName,
                                 bool isReadOnly) override {
      uint8_t *Addr = SectionMemoryManager::allocateDataSection(Size, Alignment, SectionID, SectionName, isReadOnly);
      //printf("allocateDataSection: %s Addr %p Size %ld Alignment %d SectionID %d RO %d\n",
      //       SectionName.str().c_str(), (void *)Addr, Size, Alignment, SectionID, isReadOnly);
      (*sections_)[SectionName.str()] = make_tuple(Addr, Size);
      return Addr;
    }
    map<string, tuple<uint8_t *, uintptr_t>> *sections_;
  };
  
  BPFModule::BPFModule(unsigned flags, TableStorage *ts, bool rw_engine_enabled)
      : flags_(flags),
        rw_engine_enabled_(rw_engine_enabled),
        used_b_loader_(false),
        ctx_(new LLVMContext),
        id_(std::to_string((uintptr_t)this)),
        ts_(ts) {
    InitializeNativeTarget();
    InitializeNativeTargetAsmPrinter();
    LLVMInitializeBPFTarget();
    LLVMInitializeBPFTargetMC();
    LLVMInitializeBPFTargetInfo();
    LLVMInitializeBPFAsmPrinter();
  #if LLVM_MAJOR_VERSION >= 6
    LLVMInitializeBPFAsmParser();
    if (flags & DEBUG_SOURCE)
      LLVMInitializeBPFDisassembler();
  #endif
    LLVMLinkInMCJIT(); /* call empty function to force linking of MCJIT */
    if (!ts_) {
      local_ts_ = createSharedTableStorage();
      ts_ = &*local_ts_;
    }
    func_src_ = ebpf::make_unique<FuncSource>();
  }
  
  static StatusTuple unimplemented_sscanf(const char *, void *) {
    return StatusTuple(-1, "sscanf unimplemented");
  }
  static StatusTuple unimplemented_snprintf(char *, size_t, const void *) {
    return StatusTuple(-1, "snprintf unimplemented");
  }
  
  BPFModule::~BPFModule() {
    for (auto &v : tables_) {
      v->key_sscanf = unimplemented_sscanf;
      v->leaf_sscanf = unimplemented_sscanf;
      v->key_snprintf = unimplemented_snprintf;
      v->leaf_snprintf = unimplemented_snprintf;
    }
  
    if (!rw_engine_enabled_) {
      for (auto section : sections_)
        delete[] get<0>(section.second);
    }
  
    engine_.reset();
    rw_engine_.reset();
    ctx_.reset();
    func_src_.reset();
  
    ts_->DeletePrefix(Path({id_}));
  }
  
  static void debug_printf(Module *mod, IRBuilder<> &B, const string &fmt, vector<Value *> args) {
    GlobalVariable *fmt_gvar = B.CreateGlobalString(fmt, "fmt");
    args.insert(args.begin(), B.CreateInBoundsGEP(fmt_gvar, vector<Value *>({B.getInt64(0), B.getInt64(0)})));
    args.insert(args.begin(), B.getInt64((uintptr_t)stderr));
    Function *fprintf_fn = mod->getFunction("fprintf");
    if (!fprintf_fn) {
      vector<Type *> fprintf_fn_args({B.getInt64Ty(), B.getInt8PtrTy()});
      FunctionType *fprintf_fn_type = FunctionType::get(B.getInt32Ty(), fprintf_fn_args, /*isvarArg=*/true);
      fprintf_fn = Function::Create(fprintf_fn_type, GlobalValue::ExternalLinkage, "fprintf", mod);
      fprintf_fn->setCallingConv(CallingConv::C);
      fprintf_fn->addFnAttr(Attribute::NoUnwind);
    }
    B.CreateCall(fprintf_fn, args);
  }
  
  static void finish_sscanf(IRBuilder<> &B, vector<Value *> *args, string *fmt,
                            const map<string, Value *> &locals, bool exact_args) {
    // fmt += "%n";
    // int nread = 0;
    // int n = sscanf(s, fmt, args..., &nread);
    // if (n < 0) return -1;
    // s = &s[nread];
    Value *sptr = locals.at("sptr");
    Value *nread = locals.at("nread");
    Function *cur_fn = B.GetInsertBlock()->getParent();
    Function *sscanf_fn = B.GetInsertBlock()->getModule()->getFunction("sscanf");
    *fmt += "%n";
    B.CreateStore(B.getInt32(0), nread);
    GlobalVariable *fmt_gvar = B.CreateGlobalString(*fmt, "fmt");
    (*args)[1] = B.CreateInBoundsGEP(fmt_gvar, {B.getInt64(0), B.getInt64(0)});
    (*args)[0] = B.CreateLoad(sptr);
    args->push_back(nread);
    CallInst *call = B.CreateCall(sscanf_fn, *args);
    call->setTailCall(true);
  
    BasicBlock *label_true = BasicBlock::Create(B.getContext(), "", cur_fn);
    BasicBlock *label_false = BasicBlock::Create(B.getContext(), "", cur_fn);
  
    // exact_args means fail if don't consume exact number of "%" inputs
    // exact_args is disabled for string parsing (empty case)
    Value *cond = exact_args ? B.CreateICmpNE(call, B.getInt32(args->size() - 3))
                             : B.CreateICmpSLT(call, B.getInt32(0));
    B.CreateCondBr(cond, label_true, label_false);
  
    B.SetInsertPoint(label_true);
    B.CreateRet(B.getInt32(-1));
  
    B.SetInsertPoint(label_false);
    // s = &s[nread];
    B.CreateStore(
        B.CreateInBoundsGEP(B.CreateLoad(sptr), B.CreateLoad(nread, true)), sptr);
  
    args->resize(2);
    fmt->clear();
  }
  
  // recursive helper to capture the arguments
  static void parse_type(IRBuilder<> &B, vector<Value *> *args, string *fmt,
                         Type *type, Value *out,
                         const map<string, Value *> &locals, bool is_writer) {
    if (StructType *st = dyn_cast<StructType>(type)) {
      *fmt += "{ ";
      unsigned idx = 0;
      for (auto field : st->elements()) {
        parse_type(B, args, fmt, field, B.CreateStructGEP(type, out, idx++),
                   locals, is_writer);
        *fmt += " ";
      }
      *fmt += "}";
    } else if (ArrayType *at = dyn_cast<ArrayType>(type)) {
      if (at->getElementType() == B.getInt8Ty()) {
        // treat i8[] as a char string instead of as an array of u8's
        if (is_writer) {
          *fmt += "\"%s\"";
          args->push_back(out);
        } else {
          // When reading strings, scanf doesn't support empty "", so we need to
          // break this up into multiple scanf calls. To understand it, let's take
          // an example:
          // struct Event {
          //   u32 a;
          //   struct {
          //     char x[64];
          //     int y;
          //   } b[2];
          //   u32 c;
          // };
          // The writer string would look like:
          //  "{ 0x%x [ { \"%s\" 0x%x } { \"%s\" 0x%x } ] 0x%x }"
          // But the reader string needs to restart at each \"\".
          //  reader0(const char *s, struct Event *val) {
          //    int nread, rc;
          //    nread = 0;
          //    rc = sscanf(s, "{ %i [ { \"%n", &val->a, &nread);
          //    if (rc != 1) return -1;
          //    s += nread; nread = 0;
          //    rc = sscanf(s, "%[^\"]%n", &val->b[0].x, &nread);
          //    if (rc < 0) return -1;
          //    s += nread; nread = 0;
          //    rc = sscanf(s, "\" %i } { \"%n", &val->b[0].y, &nread);
          //    if (rc != 1) return -1;
          //    s += nread; nread = 0;
          //    rc = sscanf(s, "%[^\"]%n", &val->b[1].x, &nread);
          //    if (rc < 0) return -1;
          //    s += nread; nread = 0;
          //    rc = sscanf(s, "\" %i } ] %i }%n", &val->b[1].y, &val->c, &nread);
          //    if (rc != 2) return -1;
          //    s += nread; nread = 0;
          //    return 0;
          //  }
          *fmt += "\"";
          finish_sscanf(B, args, fmt, locals, true);
  
          *fmt = "%[^\"]";
          args->push_back(out);
          finish_sscanf(B, args, fmt, locals, false);
  
          *fmt = "\"";
        }
      } else {
        *fmt += "[ ";
        for (size_t i = 0; i < at->getNumElements(); ++i) {
          parse_type(B, args, fmt, at->getElementType(),
                     B.CreateStructGEP(type, out, i), locals, is_writer);
          *fmt += " ";
        }
        *fmt += "]";
      }
    } else if (isa<PointerType>(type)) {
      *fmt += "0xl";
      if (is_writer)
        *fmt += "x";
      else
        *fmt += "i";
    } else if (IntegerType *it = dyn_cast<IntegerType>(type)) {
      if (is_writer)
        *fmt += "0x";
      if (it->getBitWidth() <= 8)
        *fmt += "%hh";
      else if (it->getBitWidth() <= 16)
        *fmt += "%h";
      else if (it->getBitWidth() <= 32)
        *fmt += "%";
      else
        *fmt += "%l";
      if (is_writer)
        *fmt += "x";
      else
        *fmt += "i";
      args->push_back(is_writer ? B.CreateLoad(out) : out);
    }
  }
  
  // make_reader generates a dynamic function in the instruction set of the host
  // (not bpf) that is able to convert c-strings in the pretty-print format of
  // make_writer back into binary representations. The encoding of the string
  // takes the llvm ir structure format, which closely maps the c structure but
  // not exactly (no support for unions for instance).
  // The general algorithm is:
  //  pod types (u8..u64)                <= %i
  //  array types
  //   u8[]  no nested quotes :(         <= "..."
  //   !u8[]                             <= [ %i %i ... ]
  //  struct types
  //   struct { u8 a; u64 b; }           <= { %i %i }
  //  nesting is supported
  //   struct { struct { u8 a[]; }; }    <= { "" }
  //   struct { struct { u64 a[]; }; }   <= { [ %i %i .. ] }
  string BPFModule::make_reader(Module *mod, Type *type) {
    auto fn_it = readers_.find(type);
    if (fn_it != readers_.end())
      return fn_it->second;
  
    // int read(const char *in, Type *out) {
    //   int n = sscanf(in, "{ %i ... }", &out->field1, ...);
    //   if (n != num_fields) return -1;
    //   return 0;
    // }
  
    IRBuilder<> B(*ctx_);
  
    FunctionType *sscanf_fn_type = FunctionType::get(
        B.getInt32Ty(), {B.getInt8PtrTy(), B.getInt8PtrTy()}, /*isVarArg=*/true);
    Function *sscanf_fn = mod->getFunction("sscanf");
    if (!sscanf_fn) {
      sscanf_fn = Function::Create(sscanf_fn_type, GlobalValue::ExternalLinkage,
                                   "sscanf", mod);
      sscanf_fn->setCallingConv(CallingConv::C);
      sscanf_fn->addFnAttr(Attribute::NoUnwind);
    }
  
    string name = "reader" + std::to_string(readers_.size());
    vector<Type *> fn_args({B.getInt8PtrTy(), PointerType::getUnqual(type)});
    FunctionType *fn_type = FunctionType::get(B.getInt32Ty(), fn_args, /*isVarArg=*/false);
    Function *fn =
        Function::Create(fn_type, GlobalValue::ExternalLinkage, name, mod);
    auto arg_it = fn->arg_begin();
    Argument *arg_in = &*arg_it;
    ++arg_it;
    arg_in->setName("in");
    Argument *arg_out = &*arg_it;
    ++arg_it;
    arg_out->setName("out");
  
    BasicBlock *label_entry = BasicBlock::Create(*ctx_, "entry", fn);
    B.SetInsertPoint(label_entry);
  
    Value *nread = B.CreateAlloca(B.getInt32Ty());
    Value *sptr = B.CreateAlloca(B.getInt8PtrTy());
    map<string, Value *> locals{{"nread", nread}, {"sptr", sptr}};
    B.CreateStore(arg_in, sptr);
    vector<Value *> args({nullptr, nullptr});
    string fmt;
    parse_type(B, &args, &fmt, type, arg_out, locals, false);
  
    if (0)
      debug_printf(mod, B, "%p %p\n", vector<Value *>({arg_in, arg_out}));
  
    finish_sscanf(B, &args, &fmt, locals, true);
  
    B.CreateRet(B.getInt32(0));
  
    readers_[type] = name;
    return name;
  }
  
  // make_writer generates a dynamic function in the instruction set of the host
  // (not bpf) that is able to pretty-print key/leaf entries as a c-string. The
  // encoding of the string takes the llvm ir structure format, which closely maps
  // the c structure but not exactly (no support for unions for instance).
  // The general algorithm is:
  //  pod types (u8..u64)                => 0x%x
  //  array types
  //   u8[]                              => "..."
  //   !u8[]                             => [ 0x%x 0x%x ... ]
  //  struct types
  //   struct { u8 a; u64 b; }           => { 0x%x 0x%x }
  //  nesting is supported
  //   struct { struct { u8 a[]; }; }    => { "" }
  //   struct { struct { u64 a[]; }; }   => { [ 0x%x 0x%x .. ] }
  string BPFModule::make_writer(Module *mod, Type *type) {
    auto fn_it = writers_.find(type);
    if (fn_it != writers_.end())
      return fn_it->second;
  
    // int write(int len, char *out, Type *in) {
    //   return snprintf(out, len, "{ %i ... }", out->field1, ...);
    // }
  
    IRBuilder<> B(*ctx_);
  
    string name = "writer" + std::to_string(writers_.size());
    vector<Type *> fn_args({B.getInt8PtrTy(), B.getInt64Ty(), PointerType::getUnqual(type)});
    FunctionType *fn_type = FunctionType::get(B.getInt32Ty(), fn_args, /*isVarArg=*/false);
    Function *fn =
        Function::Create(fn_type, GlobalValue::ExternalLinkage, name, mod);
    auto arg_it = fn->arg_begin();
    Argument *arg_out = &*arg_it;
    ++arg_it;
    arg_out->setName("out");
    Argument *arg_len = &*arg_it;
    ++arg_it;
    arg_len->setName("len");
    Argument *arg_in = &*arg_it;
    ++arg_it;
    arg_in->setName("in");
  
    BasicBlock *label_entry = BasicBlock::Create(*ctx_, "entry", fn);
    B.SetInsertPoint(label_entry);
  
    map<string, Value *> locals{
        {"nread", B.CreateAlloca(B.getInt64Ty())},
    };
    vector<Value *> args({arg_out, B.CreateZExt(arg_len, B.getInt64Ty()), nullptr});
    string fmt;
    parse_type(B, &args, &fmt, type, arg_in, locals, true);
  
    GlobalVariable *fmt_gvar = B.CreateGlobalString(fmt, "fmt");
  
    args[2] = B.CreateInBoundsGEP(fmt_gvar, vector<Value *>({B.getInt64(0), B.getInt64(0)}));
  
    if (0)
      debug_printf(mod, B, "%d %p %p\n", vector<Value *>({arg_len, arg_out, arg_in}));
  
    vector<Type *> snprintf_fn_args({B.getInt8PtrTy(), B.getInt64Ty(), B.getInt8PtrTy()});
    FunctionType *snprintf_fn_type = FunctionType::get(B.getInt32Ty(), snprintf_fn_args, /*isVarArg=*/true);
    Function *snprintf_fn = mod->getFunction("snprintf");
    if (!snprintf_fn)
      snprintf_fn = Function::Create(snprintf_fn_type, GlobalValue::ExternalLinkage, "snprintf", mod);
    snprintf_fn->setCallingConv(CallingConv::C);
    snprintf_fn->addFnAttr(Attribute::NoUnwind);
  
    CallInst *call = B.CreateCall(snprintf_fn, args);
    call->setTailCall(true);
  
    B.CreateRet(call);
  
    writers_[type] = name;
    return name;
  }
  
  unique_ptr<ExecutionEngine> BPFModule::finalize_rw(unique_ptr<Module> m) {
    Module *mod = &*m;
  
    run_pass_manager(*mod);
  
    string err;
    EngineBuilder builder(move(m));
    builder.setErrorStr(&err);
    builder.setUseOrcMCJITReplacement(false);
    auto engine = unique_ptr<ExecutionEngine>(builder.create());
    if (!engine)
      fprintf(stderr, "Could not create ExecutionEngine: %s\n", err.c_str());
    return engine;
  }
  
  // load an entire c file as a module
  int BPFModule::load_cfile(const string &file, bool in_memory, const char *cflags[], int ncflags) {
    ClangLoader clang_loader(&*ctx_, flags_);
    if (clang_loader.parse(&mod_, *ts_, file, in_memory, cflags, ncflags, id_,
                           *func_src_, mod_src_))
      return -1;
    return 0;
  }
  
  // NOTE: this is a duplicate of the above, but planning to deprecate if we
  // settle on clang as the frontend
  
  // Load in a pre-built list of functions into the initial Module object, then
  // build an ExecutionEngine.
  int BPFModule::load_includes(const string &text) {
    ClangLoader clang_loader(&*ctx_, flags_);
    if (clang_loader.parse(&mod_, *ts_, text, true, nullptr, 0, "", *func_src_,
                           mod_src_))
      return -1;
    return 0;
  }
  
  void BPFModule::annotate_light() {
    for (auto fn = mod_->getFunctionList().begin(); fn != mod_->getFunctionList().end(); ++fn)
      if (!fn->hasFnAttribute(Attribute::NoInline))
        fn->addFnAttr(Attribute::AlwaysInline);
  
    size_t id = 0;
    Path path({id_});
    for (auto it = ts_->lower_bound(path), up = ts_->upper_bound(path); it != up; ++it) {
      TableDesc &table = it->second;
      tables_.push_back(&it->second);
      table_names_[table.name] = id++;
    }
  }
  
  int BPFModule::annotate() {
    for (auto fn = mod_->getFunctionList().begin(); fn != mod_->getFunctionList().end(); ++fn)
      if (!fn->hasFnAttribute(Attribute::NoInline))
        fn->addFnAttr(Attribute::AlwaysInline);
  
    // separate module to hold the reader functions
    auto m = ebpf::make_unique<Module>("sscanf", *ctx_);
  
    size_t id = 0;
    Path path({id_});
    for (auto it = ts_->lower_bound(path), up = ts_->upper_bound(path); it != up; ++it) {
      TableDesc &table = it->second;
      tables_.push_back(&it->second);
      table_names_[table.name] = id++;
      GlobalValue *gvar = mod_->getNamedValue(table.name);
      if (!gvar) continue;
      if (PointerType *pt = dyn_cast<PointerType>(gvar->getType())) {
        if (StructType *st = dyn_cast<StructType>(pt->getElementType())) {
          if (st->getNumElements() < 2) continue;
          Type *key_type = st->elements()[0];
          Type *leaf_type = st->elements()[1];
  
          using std::placeholders::_1;
          using std::placeholders::_2;
          using std::placeholders::_3;
          table.key_sscanf = std::bind(&BPFModule::sscanf, this,
                                       make_reader(&*m, key_type), _1, _2);
          table.leaf_sscanf = std::bind(&BPFModule::sscanf, this,
                                        make_reader(&*m, leaf_type), _1, _2);
          table.key_snprintf = std::bind(&BPFModule::snprintf, this,
                                         make_writer(&*m, key_type), _1, _2, _3);
          table.leaf_snprintf =
              std::bind(&BPFModule::snprintf, this, make_writer(&*m, leaf_type),
                        _1, _2, _3);
        }
      }
    }
  
    rw_engine_ = finalize_rw(move(m));
    if (!rw_engine_)
      return -1;
    return 0;
  }
  
  StatusTuple BPFModule::sscanf(string fn_name, const char *str, void *val) {
    if (!rw_engine_enabled_)
      return StatusTuple(-1, "rw_engine not enabled");
    auto fn =
        (int (*)(const char *, void *))rw_engine_->getFunctionAddress(fn_name);
    if (!fn)
      return StatusTuple(-1, "sscanf not available");
    int rc = fn(str, val);
    if (rc < 0)
      return StatusTuple(rc, "error in sscanf: %s", std::strerror(errno));
    return StatusTuple(rc);
  }
  
  StatusTuple BPFModule::snprintf(string fn_name, char *str, size_t sz,
                                  const void *val) {
    if (!rw_engine_enabled_)
      return StatusTuple(-1, "rw_engine not enabled");
    auto fn = (int (*)(char *, size_t,
                       const void *))rw_engine_->getFunctionAddress(fn_name);
    if (!fn)
      return StatusTuple(-1, "snprintf not available");
    int rc = fn(str, sz, val);
    if (rc < 0)
      return StatusTuple(rc, "error in snprintf: %s", std::strerror(errno));
    if ((size_t)rc == sz)
      return StatusTuple(-1, "buffer of size %zd too small", sz);
    return StatusTuple(0);
  }
  
  void BPFModule::dump_ir(Module &mod) {
    legacy::PassManager PM;
    PM.add(createPrintModulePass(errs()));
    PM.run(mod);
  }
  
  int BPFModule::run_pass_manager(Module &mod) {
    if (verifyModule(mod, &errs())) {
      if (flags_ & DEBUG_LLVM_IR)
        dump_ir(mod);
      return -1;
    }
  
    legacy::PassManager PM;
    PassManagerBuilder PMB;
    PMB.OptLevel = 3;
    PM.add(createFunctionInliningPass());
    /*
     * llvm < 4.0 needs
     * PM.add(createAlwaysInlinerPass());
     * llvm >= 4.0 needs
     * PM.add(createAlwaysInlinerLegacyPass());
     * use below 'stable' workaround
     */
    LLVMAddAlwaysInlinerPass(reinterpret_cast<LLVMPassManagerRef>(&PM));
    PMB.populateModulePassManager(PM);
    if (flags_ & DEBUG_LLVM_IR)
      PM.add(createPrintModulePass(outs()));
    PM.run(mod);
    return 0;
  }
  
  int BPFModule::finalize() {
    Module *mod = &*mod_;
    std::map<std::string, std::tuple<uint8_t *, uintptr_t>> tmp_sections,
        *sections_p;
  
    mod->setTargetTriple("bpf-pc-linux");
    sections_p = rw_engine_enabled_ ? &sections_ : &tmp_sections;
  
    string err;
    EngineBuilder builder(move(mod_));
    builder.setErrorStr(&err);
    builder.setMCJITMemoryManager(ebpf::make_unique<MyMemoryManager>(sections_p));
    builder.setMArch("bpf");
    builder.setUseOrcMCJITReplacement(false);
    engine_ = unique_ptr<ExecutionEngine>(builder.create());
    if (!engine_) {
      fprintf(stderr, "Could not create ExecutionEngine: %s\n", err.c_str());
      return -1;
    }
  
    if (flags_ & DEBUG_SOURCE)
      engine_->setProcessAllSections(true);
  
    if (int rc = run_pass_manager(*mod))
      return rc;
  
    engine_->finalizeObject();
  
    if (flags_ & DEBUG_SOURCE) {
      SourceDebugger src_debugger(mod, *sections_p, FN_PREFIX, mod_src_,
                                  src_dbg_fmap_);
      src_debugger.dump();
    }
  
    if (!rw_engine_enabled_) {
      // Setup sections_ correctly and then free llvm internal memory
      for (auto section : tmp_sections) {
        auto fname = section.first;
        uintptr_t size = get<1>(section.second);
        uint8_t *tmp_p = NULL;
        // Only copy data for non-map sections
        if (strncmp("maps/", section.first.c_str(), 5)) {
          uint8_t *addr = get<0>(section.second);
          tmp_p = new uint8_t[size];
          memcpy(tmp_p, addr, size);
        }
        sections_[fname] = make_tuple(tmp_p, size);
      }
      engine_.reset();
      ctx_.reset();
    }
  
    // give functions an id
    for (auto section : sections_)
      if (!strncmp(FN_PREFIX.c_str(), section.first.c_str(), FN_PREFIX.size()))
        function_names_.push_back(section.first);
  
    return 0;
  }
  
  size_t BPFModule::num_functions() const {
    return function_names_.size();
  }
  
  const char * BPFModule::function_name(size_t id) const {
    if (id >= function_names_.size())
      return nullptr;
    return function_names_[id].c_str() + FN_PREFIX.size();
  }
  
  uint8_t * BPFModule::function_start(size_t id) const {
    if (id >= function_names_.size())
      return nullptr;
    auto section = sections_.find(function_names_[id]);
    if (section == sections_.end())
      return nullptr;
    return get<0>(section->second);
  }
  
  uint8_t * BPFModule::function_start(const string &name) const {
    auto section = sections_.find(FN_PREFIX + name);
    if (section == sections_.end())
      return nullptr;
  
    return get<0>(section->second);
  }
  
  const char * BPFModule::function_source(const string &name) const {
    return func_src_->src(name);
  }
  
  const char * BPFModule::function_source_rewritten(const string &name) const {
    return func_src_->src_rewritten(name);
  }
  
  int BPFModule::annotate_prog_tag(const string &name, int prog_fd,
                                   struct bpf_insn *insns, int prog_len) {
    unsigned long long tag1, tag2;
    int err;
  
    err = bpf_prog_compute_tag(insns, prog_len, &tag1);
    if (err)
      return err;
    err = bpf_prog_get_tag(prog_fd, &tag2);
    if (err)
      return err;
    if (tag1 != tag2) {
      fprintf(stderr, "prog tag mismatch %llx %llx\n", tag1, tag2);
      return -1;
    }
  
    err = mkdir(BCC_PROG_TAG_DIR, 0777);
    if (err && errno != EEXIST) {
      fprintf(stderr, "cannot create " BCC_PROG_TAG_DIR "\n");
      return -1;
    }
  
    char buf[128];
    ::snprintf(buf, sizeof(buf), BCC_PROG_TAG_DIR "/bpf_prog_%llx", tag1);
    err = mkdir(buf, 0777);
    if (err && errno != EEXIST) {
      fprintf(stderr, "cannot create %s\n", buf);
      return -1;
    }
  
    ::snprintf(buf, sizeof(buf), BCC_PROG_TAG_DIR "/bpf_prog_%llx/%s.c",
               tag1, name.data());
    FileDesc fd(open(buf, O_CREAT | O_WRONLY | O_TRUNC, 0644));
    if (fd < 0) {
      fprintf(stderr, "cannot create %s\n", buf);
      return -1;
    }
  
    const char *src = function_source(name);
    write(fd, src, strlen(src));
  
    ::snprintf(buf, sizeof(buf), BCC_PROG_TAG_DIR "/bpf_prog_%llx/%s.rewritten.c",
               tag1, name.data());
    fd = open(buf, O_CREAT | O_WRONLY | O_TRUNC, 0644);
    if (fd < 0) {
      fprintf(stderr, "cannot create %s\n", buf);
      return -1;
    }
  
    src = function_source_rewritten(name);
    write(fd, src, strlen(src));
  
    if (!src_dbg_fmap_[name].empty()) {
      ::snprintf(buf, sizeof(buf), BCC_PROG_TAG_DIR "/bpf_prog_%llx/%s.dis.txt",
                 tag1, name.data());
      fd = open(buf, O_CREAT | O_WRONLY | O_TRUNC, 0644);
      if (fd < 0) {
        fprintf(stderr, "cannot create %s\n", buf);
        return -1;
      }
  
      const char *src = src_dbg_fmap_[name].c_str();
      write(fd, src, strlen(src));
    }
  
    return 0;
  }
  
  size_t BPFModule::function_size(size_t id) const {
    if (id >= function_names_.size())
      return 0;
    auto section = sections_.find(function_names_[id]);
    if (section == sections_.end())
      return 0;
    return get<1>(section->second);
  }
  
  size_t BPFModule::function_size(const string &name) const {
    auto section = sections_.find(FN_PREFIX + name);
    if (section == sections_.end())
      return 0;
  
    return get<1>(section->second);
  }
  
  char * BPFModule::license() const {
    auto section = sections_.find("license");
    if (section == sections_.end())
      return nullptr;
  
    return (char *)get<0>(section->second);
  }
  
  unsigned BPFModule::kern_version() const {
    auto section = sections_.find("version");
    if (section == sections_.end())
      return 0;
  
    return *(unsigned *)get<0>(section->second);
  }
  
  size_t BPFModule::num_tables() const { return tables_.size(); }
  
  size_t BPFModule::table_id(const string &name) const {
    auto it = table_names_.find(name);
    if (it == table_names_.end()) return ~0ull;
    return it->second;
  }
  
  int BPFModule::table_fd(const string &name) const {
    return table_fd(table_id(name));
  }
  
  int BPFModule::table_fd(size_t id) const {
    if (id >= tables_.size())
      return -1;
    return tables_[id]->fd;
  }
  
  int BPFModule::table_type(const string &name) const {
    return table_type(table_id(name));
  }
  
  int BPFModule::table_type(size_t id) const {
    if (id >= tables_.size())
      return -1;
    return tables_[id]->type;
  }
  
  size_t BPFModule::table_max_entries(const string &name) const {
    return table_max_entries(table_id(name));
  }
  
  size_t BPFModule::table_max_entries(size_t id) const {
    if (id >= tables_.size())
      return 0;
    return tables_[id]->max_entries;
  }
  
  int BPFModule::table_flags(const string &name) const {
    return table_flags(table_id(name));
  }
  
  int BPFModule::table_flags(size_t id) const {
    if (id >= tables_.size())
      return -1;
    return tables_[id]->flags;
  }
  
  const char * BPFModule::table_name(size_t id) const {
    if (id >= tables_.size())
      return nullptr;
    return tables_[id]->name.c_str();
  }
  
  const char * BPFModule::table_key_desc(size_t id) const {
    if (used_b_loader_) return nullptr;
    if (id >= tables_.size())
      return nullptr;
    return tables_[id]->key_desc.c_str();
  }
  
  const char * BPFModule::table_key_desc(const string &name) const {
    return table_key_desc(table_id(name));
  }
  
  const char * BPFModule::table_leaf_desc(size_t id) const {
    if (used_b_loader_) return nullptr;
    if (id >= tables_.size())
      return nullptr;
    return tables_[id]->leaf_desc.c_str();
  }
  
  const char * BPFModule::table_leaf_desc(const string &name) const {
    return table_leaf_desc(table_id(name));
  }
  size_t BPFModule::table_key_size(size_t id) const {
    if (id >= tables_.size())
      return 0;
    return tables_[id]->key_size;
  }
  size_t BPFModule::table_key_size(const string &name) const {
    return table_key_size(table_id(name));
  }
  
  size_t BPFModule::table_leaf_size(size_t id) const {
    if (id >= tables_.size())
      return 0;
    return tables_[id]->leaf_size;
  }
  size_t BPFModule::table_leaf_size(const string &name) const {
    return table_leaf_size(table_id(name));
  }
  
  struct TableIterator {
    TableIterator(size_t key_size, size_t leaf_size)
        : key(new uint8_t[key_size]), leaf(new uint8_t[leaf_size]) {
    }
    unique_ptr<uint8_t[]> key;
    unique_ptr<uint8_t[]> leaf;
    uint8_t keyb[512];
  };
  
  int BPFModule::table_key_printf(size_t id, char *buf, size_t buflen, const void *key) {
    if (id >= tables_.size())
      return -1;
    const TableDesc &desc = *tables_[id];
    StatusTuple rc = desc.key_snprintf(buf, buflen, key);
    if (rc.code() < 0) {
      fprintf(stderr, "%s\n", rc.msg().c_str());
      return -1;
    }
    return 0;
  }
  
  int BPFModule::table_leaf_printf(size_t id, char *buf, size_t buflen, const void *leaf) {
    if (id >= tables_.size())
      return -1;
    const TableDesc &desc = *tables_[id];
    StatusTuple rc = desc.leaf_snprintf(buf, buflen, leaf);
    if (rc.code() < 0) {
      fprintf(stderr, "%s\n", rc.msg().c_str());
      return -1;
    }
    return 0;
  }
  
  int BPFModule::table_key_scanf(size_t id, const char *key_str, void *key) {
    if (id >= tables_.size())
      return -1;
    const TableDesc &desc = *tables_[id];
    StatusTuple rc = desc.key_sscanf(key_str, key);
    if (rc.code() < 0) {
      fprintf(stderr, "%s\n", rc.msg().c_str());
      return -1;
    }
    return 0;
  }
  
  int BPFModule::table_leaf_scanf(size_t id, const char *leaf_str, void *leaf) {
    if (id >= tables_.size())
      return -1;
    const TableDesc &desc = *tables_[id];
    StatusTuple rc = desc.leaf_sscanf(leaf_str, leaf);
    if (rc.code() < 0) {
      fprintf(stderr, "%s\n", rc.msg().c_str());
      return -1;
    }
    return 0;
  }
  
  // load a B file, which comes in two parts
  int BPFModule::load_b(const string &filename, const string &proto_filename) {
    if (!sections_.empty()) {
      fprintf(stderr, "Program already initialized\n");
      return -1;
    }
    if (filename.empty() || proto_filename.empty()) {
      fprintf(stderr, "Invalid filenames\n");
      return -1;
    }
  
    // Helpers are inlined in the following file (C). Load the definitions and
    // pass the partially compiled module to the B frontend to continue with.
    auto helpers_h = ExportedFiles::headers().find("/virtual/include/bcc/helpers.h");
    if (helpers_h == ExportedFiles::headers().end()) {
      fprintf(stderr, "Internal error: missing bcc/helpers.h");
      return -1;
    }
    if (int rc = load_includes(helpers_h->second))
      return rc;
  
    BLoader b_loader(flags_);
    used_b_loader_ = true;
    if (int rc = b_loader.parse(&*mod_, filename, proto_filename, *ts_, id_))
      return rc;
    if (rw_engine_enabled_) {
      if (int rc = annotate())
        return rc;
    } else {
      annotate_light();
    }
    if (int rc = finalize())
      return rc;
    return 0;
  }
  
  // load a C file
  int BPFModule::load_c(const string &filename, const char *cflags[], int ncflags) {
    if (!sections_.empty()) {
      fprintf(stderr, "Program already initialized\n");
      return -1;
    }
    if (filename.empty()) {
      fprintf(stderr, "Invalid filename\n");
      return -1;
    }
    if (int rc = load_cfile(filename, false, cflags, ncflags))
      return rc;
    if (rw_engine_enabled_) {
      if (int rc = annotate())
        return rc;
    } else {
      annotate_light();
    }
    if (int rc = finalize())
      return rc;
    return 0;
  }
  
  // load a C text string
  int BPFModule::load_string(const string &text, const char *cflags[], int ncflags) {
    if (!sections_.empty()) {
      fprintf(stderr, "Program already initialized\n");
      return -1;
    }
    if (int rc = load_cfile(text, true, cflags, ncflags))
      return rc;
    if (rw_engine_enabled_) {
      if (int rc = annotate())
        return rc;
    } else {
      annotate_light();
    }
  
    if (int rc = finalize())
      return rc;
    return 0;
  }
  
  } // namespace ebpf
  