path: root/lib/Analysis/NaCl/PNaClABIVerifyModule.cpp

//===- PNaClABIVerifyModule.cpp - Verify PNaCl ABI rules ------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Verify module-level PNaCl ABI requirements (specifically those that do not
// require looking at the function bodies)
//
//
//===----------------------------------------------------------------------===//

#include "llvm/Pass.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/NaCl.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"

#include "PNaClABITypeChecker.h"
using namespace llvm;

namespace llvm {
cl::opt<bool>
PNaClABIAllowDebugMetadata("pnaclabi-allow-debug-metadata",
  cl::desc("Allow debug metadata during PNaCl ABI verification."),
  cl::init(false));

}

static cl::opt<bool>
PNaClABIAllowDevIntrinsics("pnaclabi-allow-dev-intrinsics",
  cl::desc("Allow all LLVM intrinsics during PNaCl ABI verification."),
  cl::init(true));  // TODO(jvoung): Make this false by default.

namespace {
// This pass should not touch function bodies, to stay streaming-friendly
class PNaClABIVerifyModule : public ModulePass {
 public:
  static char ID;
  PNaClABIVerifyModule() :
      ModulePass(ID),
      Reporter(new PNaClABIErrorReporter),
      ReporterIsOwned(true) {
    initializePNaClABIVerifyModulePass(*PassRegistry::getPassRegistry());
  }
  explicit PNaClABIVerifyModule(PNaClABIErrorReporter *Reporter_,
                                bool StreamingMode) :
      ModulePass(ID),
      Reporter(Reporter_),
      ReporterIsOwned(false),
      StreamingMode(StreamingMode) {
    initializePNaClABIVerifyModulePass(*PassRegistry::getPassRegistry());
  }
  ~PNaClABIVerifyModule() {
    if (ReporterIsOwned)
      delete Reporter;
  }
  bool runOnModule(Module &M);
  virtual void print(raw_ostream &O, const Module *M) const;
 private:
  void checkGlobalValueCommon(const GlobalValue *GV);
  bool isWhitelistedIntrinsic(const Function *F, unsigned ID);
  bool isWhitelistedMetadata(const NamedMDNode *MD);
  void checkGlobalIsFlattened(const GlobalVariable *GV);
  PNaClABIErrorReporter *Reporter;
  bool ReporterIsOwned;
  bool StreamingMode;
};

static const char *linkageName(GlobalValue::LinkageTypes LT) {
  // This logic is taken from PrintLinkage in lib/VMCore/AsmWriter.cpp
  switch (LT) {
    case GlobalValue::ExternalLinkage: return "external";
    case GlobalValue::PrivateLinkage:       return "private ";
    case GlobalValue::LinkerPrivateLinkage: return "linker_private ";
    case GlobalValue::LinkerPrivateWeakLinkage: return "linker_private_weak ";
    case GlobalValue::InternalLinkage:      return "internal ";
    case GlobalValue::LinkOnceAnyLinkage:   return "linkonce ";
    case GlobalValue::LinkOnceODRLinkage:   return "linkonce_odr ";
    case GlobalValue::LinkOnceODRAutoHideLinkage:
      return "linkonce_odr_auto_hide ";
    case GlobalValue::WeakAnyLinkage:       return "weak ";
    case GlobalValue::WeakODRLinkage:       return "weak_odr ";
    case GlobalValue::CommonLinkage:        return "common ";
    case GlobalValue::AppendingLinkage:     return "appending ";
    case GlobalValue::DLLImportLinkage:     return "dllimport ";
    case GlobalValue::DLLExportLinkage:     return "dllexport ";
    case GlobalValue::ExternalWeakLinkage:  return "extern_weak ";
    case GlobalValue::AvailableExternallyLinkage:
      return "available_externally ";
    default:
      return "unknown";
  }
}

} // end anonymous namespace

// Check linkage type and section attributes, which are the same for
// GlobalVariables and Functions.
void PNaClABIVerifyModule::checkGlobalValueCommon(const GlobalValue *GV) {
  assert(!isa<GlobalAlias>(GV));
  const char *GVTypeName = isa<GlobalVariable>(GV) ?
      "Variable " : "Function ";
  switch (GV->getLinkage()) {
    // TODO(dschuff): Disallow external linkage
    case GlobalValue::ExternalLinkage:
    case GlobalValue::InternalLinkage:
      break;
    default:
      Reporter->addError() << GVTypeName << GV->getName()
                           << " has disallowed linkage type: "
                           << linkageName(GV->getLinkage()) << "\n";
  }
  if (GV->getVisibility() != GlobalValue::DefaultVisibility) {
    std::string Text = "unknown";
    if (GV->getVisibility() == GlobalValue::HiddenVisibility) {
      Text = "hidden";
    } else if (GV->getVisibility() == GlobalValue::ProtectedVisibility) {
      Text = "protected";
    }
    Reporter->addError() << GVTypeName << GV->getName()
                         << " has disallowed visibility: " << Text << "\n";
  }
  if (GV->hasSection()) {
    Reporter->addError() << GVTypeName << GV->getName() <<
        " has disallowed \"section\" attribute\n";
  }
  if (GV->getType()->getAddressSpace() != 0) {
    Reporter->addError() << GVTypeName << GV->getName()
                         << " has addrspace attribute (disallowed)\n";
  }
  // The "unnamed_addr" attribute can be used to merge duplicate
  // definitions, but that should be done by user-toolchain
  // optimization passes, not by the PNaCl translator.
  if (GV->hasUnnamedAddr()) {
    Reporter->addError() << GVTypeName << GV->getName()
                         << " has disallowed \"unnamed_addr\" attribute\n";
  }
}

static bool TypeAcceptable(const Type *T,
                           const ArrayRef<Type*> &AcceptableTypes) {
  for (ArrayRef<Type*>::iterator I = AcceptableTypes.begin(),
       E = AcceptableTypes.end(); I != E; ++I)
    if (*I == T)
      return true;
  return false;
}

// We accept bswap for a limited set of types (i16, i32, i64).
// The various backends are able to generate instructions to
// implement the intrinsic.  Also, i16 and i64 are easy to
// implement as along as there is a way to do i32.
static bool isWhitelistedBswap(const Function *F) {
  FunctionType *FT = F->getFunctionType();
  if (FT->getNumParams() != 1)
    return false;
  Type *ParamType = FT->getParamType(0);
  LLVMContext &C = F->getContext();
  Type *AcceptableTypes[] = { Type::getInt16Ty(C),
                              Type::getInt32Ty(C),
                              Type::getInt64Ty(C) };
  return TypeAcceptable(ParamType, AcceptableTypes);
}

// We accept cttz, ctlz, and ctpop for a limited set of types (i32, i64).
static bool isWhitelistedCountBits(const Function *F, unsigned num_params) {
  FunctionType *FT = F->getFunctionType();
  if (FT->getNumParams() != num_params)
    return false;
  Type *ParamType = FT->getParamType(0);
  LLVMContext &C = F->getContext();
  Type *AcceptableTypes[] = { Type::getInt32Ty(C), Type::getInt64Ty(C) };
  return TypeAcceptable(ParamType, AcceptableTypes);
}

bool PNaClABIVerifyModule::isWhitelistedIntrinsic(const Function *F,
                                                  unsigned ID) {
  // Keep 3 categories of intrinsics for now.
  // (1) Allowed always
  // (2) Never allowed
  // (3) "Dev" intrinsics, which may or may not be allowed.
  // "Dev" intrinsics are controlled by the PNaClABIAllowDevIntrinsics flag.
  // Please keep these sorted or grouped in a sensible way, within
  // each category.
  switch(ID) {
    // Disallow by default.
    default: return false;
    // (1) Always allowed.
    case Intrinsic::bswap: return isWhitelistedBswap(F);
    case Intrinsic::ctlz:
    case Intrinsic::cttz: return isWhitelistedCountBits(F, 2);
    case Intrinsic::ctpop: return isWhitelistedCountBits(F, 1);
    case Intrinsic::memcpy:
    case Intrinsic::memmove:
    case Intrinsic::<