//===--- Mangle.cpp - Mangle C++ Names --------------------------*- C++ -*-===//

//

// 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 generic name mangling support for blocks and Objective-C.

//

//===----------------------------------------------------------------------===//

#include "clang/AST/Attr.h"

#include "clang/AST/ASTContext.h"

#include "clang/AST/Decl.h"

#include "clang/AST/DeclCXX.h"

#include "clang/AST/DeclObjC.h"

#include "clang/AST/DeclTemplate.h"

#include "clang/AST/ExprCXX.h"

#include "clang/AST/Mangle.h"

#include "clang/AST/VTableBuilder.h"

#include "clang/Basic/ABI.h"

#include "clang/Basic/SourceManager.h"

#include "clang/Basic/TargetInfo.h"

#include "llvm/ADT/StringExtras.h"

#include "llvm/IR/DataLayout.h"

#include "llvm/IR/Mangler.h"

#include "llvm/Support/ErrorHandling.h"

#include "llvm/Support/Format.h"

#include "llvm/Support/raw_ostream.h"

using namespace clang;

// FIXME: For blocks we currently mimic GCC's mangling scheme, which leaves

// much to be desired. Come up with a better mangling scheme.

static void mangleFunctionBlock(MangleContext &Context,

                                StringRef Outer,

                                const BlockDecl *BD,

                                raw_ostream &Out) {

  unsigned discriminator = Context.getBlockId(BD, true);

  if (discriminator == 0)

    Out << "__" << Outer << "_block_invoke";

  else

    Out << "__" << Outer << "_block_invoke_" << discriminator+1;

}

void MangleContext::anchor() { }

enum CCMangling {

  CCM_Other,

  CCM_Fast,

  CCM_RegCall,

  CCM_Vector,

  CCM_Std,

  CCM_WasmMainArgcArgv

};

static bool isExternC(const NamedDecl *ND) {

  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))

    return FD->isExternC();

  if (const VarDecl *VD = dyn_cast<VarDecl>(ND))

    return VD->isExternC();

  return false;

}

static CCMangling getCallingConvMangling(const ASTContext &Context,

                                         const NamedDecl *ND) {

  const TargetInfo &TI = Context.getTargetInfo();

  const llvm::Triple &Triple = TI.getTriple();

  // On wasm, the argc/argv form of "main" is renamed so that the startup code

  // can call it with the correct function signature.

  if (Triple.isWasm())

    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))

      if (FD->isMain() && FD->getNumParams() == 2)

        return CCM_WasmMainArgcArgv;

  if (!Triple.isOSWindows() || !Triple.isX86())

    return CCM_Other;

  if (Context.getLangOpts().CPlusPlus && !isExternC(ND) &&

      TI.getCXXABI() == TargetCXXABI::Microsoft)

    return CCM_Other;

  const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND);

  if (!FD)

    return CCM_Other;

  QualType T = FD->getType();

  const FunctionType *FT = T->castAs<FunctionType>();

  CallingConv CC = FT->getCallConv();

  switch (CC) {

  default:

    return CCM_Other;

  case CC_X86FastCall:

    return CCM_Fast;

  case CC_X86StdCall:

    return CCM_Std;

  case CC_X86VectorCall:

    return CCM_Vector;

  }

}

bool MangleContext::shouldMangleDeclName(const NamedDecl *D) {

  const ASTContext &ASTContext = getASTContext();

  CCMangling CC = getCallingConvMangling(ASTContext, D);

  if (CC != CCM_Other)

    return true;

  // If the declaration has an owning module for linkage purposes that needs to

  // be mangled, we must mangle its name.

  if (!D->hasExternalFormalLinkage() && D->getOwningModuleForLinkage())

    return true;

  // C functions with internal linkage have to be mangled with option

  // -funique-internal-linkage-names.

  if (!getASTContext().getLangOpts().CPlusPlus &&

      isUniqueInternalLinkageDecl(D))

    return true;

  // In C, functions with no attributes never need to be mangled. Fastpath them.

  if (!getASTContext().getLangOpts().CPlusPlus && !D->hasAttrs())

    return false;

  // Any decl can be declared with __asm("foo") on it, and this takes precedence

  // over all other naming in the .o file.

  if (D->hasAttr<AsmLabelAttr>())

    return true;

  // Declarations that don't have identifier names always need to be mangled.

  if (isa<MSGuidDecl>(D))

    return true;

  return shouldMangleCXXName(D);

}

void MangleContext::mangleName(GlobalDecl GD, raw_ostream &Out) {

  const ASTContext &ASTContext = getASTContext();

  const NamedDecl *D = cast<NamedDecl>(GD.getDecl());

  // Any decl can be declared with __asm("foo") on it, and this takes precedence

  // over all other naming in the .o file.

  if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {

    // If we have an asm name, then we use it as the mangling.

    // If the label isn't literal, or if this is an alias for an LLVM intrinsic,

    // do not add a "\01" prefix.

    if (!ALA->getIsLiteralLabel() || ALA->getLabel().starts_with("llvm.")) {

      Out << ALA->getLabel();

      return;

    }

    // Adding the prefix can cause problems when one file has a "foo" and

    // another has a "\01foo". That is known to happen on ELF with the

    // tricks normally used for producing aliases (PR9177). Fortunately the

    // llvm mangler on ELF is a nop, so we can just avoid adding the \01

    // marker.

    StringRef UserLabelPrefix =

        getASTContext().getTargetInfo().getUserLabelPrefix();

#ifndef NDEBUG

    char GlobalPrefix =

        llvm::DataLayout(getASTContext().getTargetInfo().getDataLayoutString())

            .getGlobalPrefix();

    assert((UserLabelPrefix.empty() && !GlobalPrefix) ||

           (UserLabelPrefix.size() == 1 && UserLabelPrefix[0] == GlobalPrefix));

#endif

    if (!UserLabelPrefix.empty())

      Out << '\01'; // LLVM IR Marker for __asm("foo")

    Out << ALA->getLabel();

    return;

  }

  if (auto *GD = dyn_cast<MSGuidDecl>(D))

    return mangleMSGuidDecl(GD, Out);

  CCMangling CC = getCallingConvMangling(ASTContext, D);

  if (CC == CCM_WasmMainArgcArgv) {

    Out << "__main_argc_argv";

    return;

  }

  bool MCXX = shouldMangleCXXName(D);

  const TargetInfo &TI = Context.getTargetInfo();

  if (CC == CCM_Other || (MCXX && TI.getCXXABI() == TargetCXXABI::Microsoft)) {

    if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D))

      mangleObjCMethodNameAsSourceName(OMD, Out);

    else

      mangleCXXName(GD, Out);

    return;

  }

  Out << '\01';

  if (CC == CCM_Std)

    Out << '_';

  else if (CC == CCM_Fast)

    Out << '@';

  else if (CC == CCM_RegCall) {

    if (getASTContext().getLangOpts().RegCall4)

      Out << "__regcall4__";

    else

      Out << "__regcall3__";

  }

  if (!MCXX)

    Out << D->getIdentifier()->getName();

  else if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D))

    mangleObjCMethodNameAsSourceName(OMD, Out);

  else

    mangleCXXName(GD, Out);

  const FunctionDecl *FD = cast<FunctionDecl>(D);

  const FunctionType *FT = FD->getType()->castAs<FunctionType>();

  const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT);

  if (CC == CCM_Vector)

    Out << '@';

  Out << '@';

  if (!Proto) {

    Out << '0';

    return;

  }

  assert(!Proto->isVariadic());

  unsigned ArgWords = 0;

  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))

    if (MD->isImplicitObjectMemberFunction())

      ++ArgWords;

  uint64_t DefaultPtrWidth = TI.getPointerWidth(LangAS::Default);

  for (const auto &AT : Proto->param_types()) {

    // If an argument type is incomplete there is no way to get its size to

    // correctly encode into the mangling scheme.

    // Follow GCCs behaviour by simply breaking out of the loop.

    if (AT->isIncompleteType())

      break;

    // Size should be aligned to pointer size.

    ArgWords += llvm::alignTo(ASTContext.getTypeSize(AT), DefaultPtrWidth) /

                DefaultPtrWidth;

  }

  Out << ((DefaultPtrWidth / 8) * ArgWords);

}

void MangleContext::mangleMSGuidDecl(const MSGuidDecl *GD, raw_ostream &Out) {

  // For now, follow the MSVC naming convention for GUID objects on all

  // targets.

  MSGuidDecl::Parts P = GD->getParts();

  Out << llvm::format("_GUID_%08" PRIx32 "_%04" PRIx32 "_%04" PRIx32 "_",

                      P.Part1, P.Part2, P.Part3);

  unsigned I = 0;

  for (uint8_t C : P.Part4And5) {

    Out << llvm::format("%02" PRIx8, C);

    if (++I == 2)

      Out << "_";

  }

}

void MangleContext::mangleGlobalBlock(const BlockDecl *BD,

                                      const NamedDecl *ID,

                                      raw_ostream &Out) {

  unsigned discriminator = getBlockId(BD, false);

  if (ID) {

    if (shouldMangleDeclName(ID))

      mangleName(ID, Out);

    else {

      Out << ID->getIdentifier()->getName();

    }

  }

  if (discriminator == 0)

    Out << "_block_invoke";

  else

    Out << "_block_invoke_" << discriminator+1;

}

void MangleContext::mangleCtorBlock(const CXXConstructorDecl *CD,

                                    CXXCtorType CT, const BlockDecl *BD,

                                    raw_ostream &ResStream) {

  SmallString<64> Buffer;

  llvm::raw_svector_ostream Out(Buffer);

  mangleName(GlobalDecl(CD, CT), Out);

  mangleFunctionBlock(*this, Buffer, BD, ResStream);

}

void MangleContext::mangleDtorBlock(const CXXDestructorDecl *DD,

                                    CXXDtorType DT, const BlockDecl *BD,

                                    raw_ostream &ResStream) {

  SmallString<64> Buffer;

  llvm::raw_svector_ostream Out(Buffer);

  mangleName(GlobalDecl(DD, DT), Out);

  mangleFunctionBlock(*this, Buffer, BD, ResStream);

}

void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD,

                                raw_ostream &Out) {

  assert(!isa<CXXConstructorDecl>(DC) && !isa<CXXDestructorDecl>(DC));

  SmallString<64> Buffer;

  llvm::raw_svector_ostream Stream(Buffer);

  if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC)) {

    mangleObjCMethodNameAsSourceName(Method, Stream);

  } else {

    assert((isa<NamedDecl>(DC) || isa<BlockDecl>(DC)) &&

           "expected a NamedDecl or BlockDecl");

    if (isa<BlockDecl>(DC))

      for (; DC && isa<BlockDecl>(DC); DC = DC->getParent())

        (void) getBlockId(cast<BlockDecl>(DC), true);

    assert((isa<TranslationUnitDecl>(DC) || isa<NamedDecl>(DC)) &&

           "expected a TranslationUnitDecl or a NamedDecl");

    if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC))

      mangleCtorBlock(CD, /*CT*/ Ctor_Complete, BD, Out);

    else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC))

      mangleDtorBlock(DD, /*DT*/ Dtor_Complete, BD, Out);

    else if (auto ND = dyn_cast<NamedDecl>(DC)) {

      if (!shouldMangleDeclName(ND) && ND->getIdentifier())

        Stream << ND->getIdentifier()->getName();

      else {

        // FIXME: We were doing a mangleUnqualifiedName() before, but that's

        // a private member of a class that will soon itself be private to the

        // Itanium C++ ABI object. What should we do now? Right now, I'm just

        // calling the mangleName() method on the MangleContext; is there a

        // better way?

        mangleName(ND, Stream);

      }

    }

  }

  mangleFunctionBlock(*this, Buffer, BD, Out);

}

void MangleContext::mangleObjCMethodName(const ObjCMethodDecl *MD,

                                         raw_ostream &OS,

                                         bool includePrefixByte,

                                         bool includeCategoryNamespace) {

  if (getASTContext().getLangOpts().ObjCRuntime.isGNUFamily()) {

    // This is the mangling we've always used on the GNU runtimes, but it

    // has obvious collisions in the face of underscores within class

    // names, category names, and selectors; maybe we should improve it.

    OS << (MD->isClassMethod() ? "_c_" : "_i_")

       << MD->getClassInterface()->getName() << '_';

    if (includeCategoryNamespace) {

      if (auto category = MD->getCategory())

        OS << category->getName();

    }

    OS << '_';

    auto selector = MD->getSelector();

    for (unsigned slotIndex = 0,

                  numArgs = selector.getNumArgs(),

                  slotEnd = std::max(numArgs, 1U);

           slotIndex != slotEnd; ++slotIndex) {

      if (auto name = selector.getIdentifierInfoForSlot(slotIndex))

        OS << name->getName();

      // Replace all the positions that would've been ':' with '_'.

      // That's after each slot except that a unary selector doesn't

      // end in ':'.

      if (numArgs)

        OS << '_';

    }

    return;

  }

  // \01+[ContainerName(CategoryName) SelectorName]

  if (includePrefixByte) {

    OS << '\01';

  }

  OS << (MD->isInstanceMethod() ? '-' : '+') << '[';

  if (const auto *CID = MD->getCategory()) {

    OS << CID->getClassInterface()->getName();

    if (includeCategoryNamespace) {

      OS << '(' << *CID << ')';

    }

  } else if (const auto *CD =

                 dyn_cast<ObjCContainerDecl>(MD->getDeclContext())) {

    OS << CD->getName();

  } else {

    llvm_unreachable("Unexpected ObjC method decl context");

  }

  OS << ' ';

  MD->getSelector().print(OS);

  OS << ']';

}

void MangleContext::mangleObjCMethodNameAsSourceName(const ObjCMethodDecl *MD,

                                                     raw_ostream &Out) {

  SmallString<64> Name;

  llvm::raw_svector_ostream OS(Name);

  mangleObjCMethodName(MD, OS, /*includePrefixByte=*/false,

                       /*includeCategoryNamespace=*/true);

  Out << OS.str().size() << OS.str();

}

class ASTNameGenerator::Implementation {

  std::unique_ptr<MangleContext> MC;

  llvm::DataLayout DL;

public:

  explicit Implementation(ASTContext &Ctx)

      : MC(Ctx.createMangleContext()),

        DL(Ctx.getTargetInfo().getDataLayoutString()) {}

  bool writeName(const Decl *D, raw_ostream &OS) {

    // First apply frontend mangling.

    SmallString<128> FrontendBuf;

    llvm::raw_svector_ostream FrontendBufOS(FrontendBuf);

    if (auto *FD = dyn_cast<FunctionDecl>(D)) {

      if (FD->isDependentContext())

        return true;

      if (writeFuncOrVarName(FD, FrontendBufOS))

        return true;

    } else if (auto *VD = dyn_cast<VarDecl>(D)) {

      if (writeFuncOrVarName(VD, FrontendBufOS))

        return true;

    } else if (auto *MD = dyn_cast<ObjCMethodDecl>(D)) {

      MC->mangleObjCMethodName(MD, OS, /*includePrefixByte=*/false,

                               /*includeCategoryNamespace=*/true);

      return false;

    } else if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) {

      writeObjCClassName(ID, FrontendBufOS);

    } else {

      return true;

    }

    // Now apply backend mangling.

    llvm::Mangler::getNameWithPrefix(OS, FrontendBufOS.str(), DL);

    return false;

  }

  std::string getName(const Decl *D) {

    std::string Name;

    {

      llvm::raw_string_ostream OS(Name);

      writeName(D, OS);

    }

    return Name;

  }

  enum ObjCKind {

    ObjCClass,

    ObjCMetaclass,

  };

  static StringRef getClassSymbolPrefix(ObjCKind Kind,

                                        const ASTContext &Context) {

    if (Context.getLangOpts().ObjCRuntime.isGNUFamily())

      return Kind == ObjCMetaclass ? "_OBJC_METACLASS_" : "_OBJC_CLASS_";

    return Kind == ObjCMetaclass ? "OBJC_METACLASS_$_" : "OBJC_CLASS_$_";

  }

  std::vector<std::string> getAllManglings(const ObjCContainerDecl *OCD) {

    StringRef ClassName;

    if (const auto *OID = dyn_cast<ObjCInterfaceDecl>(OCD))

      ClassName = OID->getObjCRuntimeNameAsString();

    else if (const auto *OID = dyn_cast<ObjCImplementationDecl>(OCD))

      ClassName = OID->getObjCRuntimeNameAsString();

    if (ClassName.empty())

      return {};

    auto Mangle = [&](ObjCKind Kind, StringRef ClassName) -> std::string {

      SmallString<40> Mangled;

      auto Prefix = getClassSymbolPrefix(Kind, OCD->getASTContext());

      llvm::Mangler::getNameWithPrefix(Mangled, Prefix + ClassName, DL);

      return std::string(Mangled.str());

    };

    return {

        Mangle(ObjCClass, ClassName),

        Mangle(ObjCMetaclass, ClassName),

    };

  }

  std::vector<std::string> getAllManglings(const Decl *D) {

    if (const auto *OCD = dyn_cast<ObjCContainerDecl>(D))

      return getAllManglings(OCD);

    if (!(isa<CXXRecordDecl>(D) || isa<CXXMethodDecl>(D)))

      return {};

    const NamedDecl *ND = cast<NamedDecl>(D);

    ASTContext &Ctx = ND->getASTContext();

    std::unique_ptr<MangleContext> M(Ctx.createMangleContext());

    std::vector<std::string> Manglings;

    auto hasDefaultCXXMethodCC = [](ASTContext &C, const CXXMethodDecl *MD) {

      auto DefaultCC = C.getDefaultCallingConvention(/*IsVariadic=*/false,

                                                     /*IsCXXMethod=*/true);

      auto CC = MD->getType()->castAs<FunctionProtoType>()->getCallConv();

      return CC == DefaultCC;

    };

    if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) {

      Manglings.emplace_back(getMangledStructor(CD, Ctor_Base));

      if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily())

        if (!CD->getParent()->isAbstract())

          Manglings.emplace_back(getMangledStructor(CD, Ctor_Complete));

      if (Ctx.getTargetInfo().getCXXABI().isMicrosoft())

        if (CD->hasAttr<DLLExportAttr>() && CD->isDefaultConstructor())

          if (!(hasDefaultCXXMethodCC(Ctx, CD) && CD->getNumParams() == 0))

            Manglings.emplace_back(getMangledStructor(CD, Ctor_DefaultClosure));

    } else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) {

      Manglings.emplace_back(getMangledStructor(DD, Dtor_Base));

      if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) {

        Manglings.emplace_back(getMangledStructor(DD, Dtor_Complete));

        if (DD->isVirtual())

          Manglings.emplace_back(getMangledStructor(DD, Dtor_Deleting));

      }

    } else if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(ND)) {

      Manglings.emplace_back(getName(ND));

      if (MD->isVirtual())

        if (const auto *TIV = Ctx.getVTableContext()->getThunkInfo(MD))

          for (const auto &T : *TIV)

            Manglings.emplace_back(getMangledThunk(MD, T));

    }

    return Manglings;

  }

private:

  bool writeFuncOrVarName(const NamedDecl *D, raw_ostream &OS) {

    if (MC->shouldMangleDeclName(D)) {

      GlobalDecl GD;

      if (const auto *CtorD = dyn_cast<CXXConstructorDecl>(D))

        GD = GlobalDecl(CtorD, Ctor_Complete);

      else if (const auto *DtorD = dyn_cast<CXXDestructorDecl>(D))

        GD = GlobalDecl(DtorD, Dtor_Complete);

      else if (D->hasAttr<CUDAGlobalAttr>())

        GD = GlobalDecl(cast<FunctionDecl>(D));

      else

        GD = GlobalDecl(D);

      MC->mangleName(GD, OS);

      return false;

    } else {

      IdentifierInfo *II = D->getIdentifier();

      if (!II)

        return true;

      OS << II->getName();

      return false;

    }

  }

  void writeObjCClassName(const ObjCInterfaceDecl *D, raw_ostream &OS) {

    OS << getClassSymbolPrefix(ObjCClass, D->getASTContext());

    OS << D->getObjCRuntimeNameAsString();

  }

  std::string getMangledStructor(const NamedDecl *ND, unsigned StructorType) {

    std::string FrontendBuf;

    llvm::raw_string_ostream FOS(FrontendBuf);

    GlobalDecl GD;

    if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND))

      GD = GlobalDecl(CD, static_cast<CXXCtorType>(StructorType));

    else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND))

      GD = GlobalDecl(DD, static_cast<CXXDtorType>(StructorType));

    MC->mangleName(GD, FOS);

    std::string BackendBuf;

    llvm::raw_string_ostream BOS(BackendBuf);

    llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL);

    return BOS.str();

  }

  std::string getMangledThunk(const CXXMethodDecl *MD, const ThunkInfo &T) {

    std::string FrontendBuf;

    llvm::raw_string_ostream FOS(FrontendBuf);

    MC->mangleThunk(MD, T, FOS);

    std::string BackendBuf;

    llvm::raw_string_ostream BOS(BackendBuf);

    llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL);

    return BOS.str();

  }

};

ASTNameGenerator::ASTNameGenerator(ASTContext &Ctx)

    : Impl(std::make_unique<Implementation>(Ctx)) {}

ASTNameGenerator::~ASTNameGenerator() {}

bool ASTNameGenerator::writeName(const Decl *D, raw_ostream &OS) {

  return Impl->writeName(D, OS);

}

std::string ASTNameGenerator::getName(const Decl *D) {

  return Impl->getName(D);

}

std::vector<std::string> ASTNameGenerator::getAllManglings(const Decl *D) {

  return Impl->getAllManglings(D);

}