path: root/lib/CodeGen/Mangle.cpp

//===--- Mangle.cpp - Mangle C++ Names --------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Implements C++ name mangling according to the Itanium C++ ABI,
// which is used in GCC 3.2 and newer (and many compilers that are
// ABI-compatible with GCC):
//
//   http://www.codesourcery.com/public/cxx-abi/abi.html
//
//===----------------------------------------------------------------------===//
#include "Mangle.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/Basic/SourceManager.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/ErrorHandling.h"
using namespace clang;

namespace {
  class VISIBILITY_HIDDEN CXXNameMangler {
    ASTContext &Context;
    llvm::raw_ostream &Out;

    const CXXMethodDecl *Structor;
    unsigned StructorType;
    CXXCtorType CtorType;

  public:
    CXXNameMangler(ASTContext &C, llvm::raw_ostream &os)
      : Context(C), Out(os), Structor(0), StructorType(0) { }

    bool mangle(const NamedDecl *D);
    void mangleCalloffset(int64_t nv, int64_t v);
    void mangleThunk(const FunctionDecl *FD, int64_t nv, int64_t v);
    void mangleCovariantThunk(const FunctionDecl *FD,
                              int64_t nv_t, int64_t v_t,
                              int64_t nv_r, int64_t v_r);
    void mangleGuardVariable(const VarDecl *D);

    void mangleCXXVtable(QualType Type);
    void mangleCXXRtti(QualType Type);
    void mangleCXXCtor(const CXXConstructorDecl *D, CXXCtorType Type);
    void mangleCXXDtor(const CXXDestructorDecl *D, CXXDtorType Type);

  private:
    bool mangleFunctionDecl(const FunctionDecl *FD);

    void mangleFunctionEncoding(const FunctionDecl *FD);
    void mangleName(const NamedDecl *ND);
    void mangleUnqualifiedName(const NamedDecl *ND);
    void mangleSourceName(const IdentifierInfo *II);
    void mangleLocalName(const NamedDecl *ND);
    void mangleNestedName(const NamedDecl *ND);
    void manglePrefix(const DeclContext *DC);
    void mangleOperatorName(OverloadedOperatorKind OO, unsigned Arity);
    void mangleCVQualifiers(unsigned Quals);
    void mangleType(QualType T);

    // Declare manglers for every type class.
#define ABSTRACT_TYPE(CLASS, PARENT)
#define NON_CANONICAL_TYPE(CLASS, PARENT)
#define TYPE(CLASS, PARENT) void mangleType(const CLASS##Type *T);
#include "clang/AST/TypeNodes.def"

    void mangleType(const TagType*);
    void mangleBareFunctionType(const FunctionType *T,
                                bool MangleReturnType);
    void mangleExpression(Expr *E);
    void mangleCXXCtorType(CXXCtorType T);
    void mangleCXXDtorType(CXXDtorType T);

    void mangleTemplateArgumentList(const TemplateArgumentList &L);
    void mangleTemplateArgument(const TemplateArgument &A);
  };
}

static bool isInCLinkageSpecification(const Decl *D) {
  for (const DeclContext *DC = D->getDeclContext();
       !DC->isTranslationUnit(); DC = DC->getParent()) {
    if (const LinkageSpecDecl *Linkage = dyn_cast<LinkageSpecDecl>(DC))
      return Linkage->getLanguage() == LinkageSpecDecl::lang_c;
  }

  return false;
}

bool CXXNameMangler::mangleFunctionDecl(const FunctionDecl *FD) {
  // Clang's "overloadable" attribute extension to C/C++ implies name mangling
  // (always).
  if (!FD->hasAttr<OverloadableAttr>()) {
    // C functions are not mangled, and "main" is never mangled.
    if (!Context.getLangOptions().CPlusPlus || FD->isMain(Context))
      return false;

    // No mangling in an "implicit extern C" header.
    if (FD->getLocation().isValid() &&
        Context.getSourceManager().isInExternCSystemHeader(FD->getLocation()))
      return false;

    // No name mangling in a C linkage specification.
    if (isInCLinkageSpecification(FD))
      return false;
  }

  // If we get here, mangle the decl name!
  Out << "_Z";
  mangleFunctionEncoding(FD);
  return true;
}

bool CXXNameMangler::mangle(const NamedDecl *D) {
  // 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.
    Out << '\01';  // LLVM IR Marker for __asm("foo")
    Out << ALA->getLabel();
    return true;
  }

  // <mangled-name> ::= _Z <encoding>
  //            ::= <data name>
  //            ::= <special-name>

  // FIXME: Actually use a visitor to decode these?
  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
    return mangleFunctionDecl(FD);