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      1 //===--- Mangle.cpp - Mangle C++ Names --------------------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // Implements generic name mangling support for blocks and Objective-C.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 #include "clang/AST/Attr.h"
     14 #include "clang/AST/ASTContext.h"
     15 #include "clang/AST/Decl.h"
     16 #include "clang/AST/DeclCXX.h"
     17 #include "clang/AST/DeclObjC.h"
     18 #include "clang/AST/DeclTemplate.h"
     19 #include "clang/AST/ExprCXX.h"
     20 #include "clang/AST/Mangle.h"
     21 #include "clang/Basic/ABI.h"
     22 #include "clang/Basic/SourceManager.h"
     23 #include "clang/Basic/TargetInfo.h"
     24 #include "llvm/ADT/StringExtras.h"
     25 #include "llvm/Support/ErrorHandling.h"
     26 #include "llvm/Support/raw_ostream.h"
     27 
     28 #define MANGLE_CHECKER 0
     29 
     30 #if MANGLE_CHECKER
     31 #include <cxxabi.h>
     32 #endif
     33 
     34 using namespace clang;
     35 
     36 // FIXME: For blocks we currently mimic GCC's mangling scheme, which leaves
     37 // much to be desired. Come up with a better mangling scheme.
     38 
     39 static void mangleFunctionBlock(MangleContext &Context,
     40                                 StringRef Outer,
     41                                 const BlockDecl *BD,
     42                                 raw_ostream &Out) {
     43   unsigned discriminator = Context.getBlockId(BD, true);
     44   if (discriminator == 0)
     45     Out << "__" << Outer << "_block_invoke";
     46   else
     47     Out << "__" << Outer << "_block_invoke_" << discriminator+1;
     48 }
     49 
     50 void MangleContext::anchor() { }
     51 
     52 enum StdOrFastCC {
     53   SOF_OTHER,
     54   SOF_FAST,
     55   SOF_STD
     56 };
     57 
     58 static bool isExternC(const NamedDecl *ND) {
     59   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))
     60     return FD->isExternC();
     61   return cast<VarDecl>(ND)->isExternC();
     62 }
     63 
     64 static StdOrFastCC getStdOrFastCallMangling(const ASTContext &Context,
     65                                             const NamedDecl *ND) {
     66   const TargetInfo &TI = Context.getTargetInfo();
     67   const llvm::Triple &Triple = TI.getTriple();
     68   if (!Triple.isOSWindows() || Triple.getArch() != llvm::Triple::x86)
     69     return SOF_OTHER;
     70 
     71   if (Context.getLangOpts().CPlusPlus && !isExternC(ND) &&
     72       TI.getCXXABI() == TargetCXXABI::Microsoft)
     73     return SOF_OTHER;
     74 
     75   const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND);
     76   if (!FD)
     77     return SOF_OTHER;
     78   QualType T = FD->getType();
     79 
     80   const FunctionType *FT = T->castAs<FunctionType>();
     81 
     82   CallingConv CC = FT->getCallConv();
     83   switch (CC) {
     84   default:
     85     return SOF_OTHER;
     86   case CC_X86FastCall:
     87     return SOF_FAST;
     88   case CC_X86StdCall:
     89     return SOF_STD;
     90   }
     91 }
     92 
     93 bool MangleContext::shouldMangleDeclName(const NamedDecl *D) {
     94   const ASTContext &ASTContext = getASTContext();
     95 
     96   StdOrFastCC CC = getStdOrFastCallMangling(ASTContext, D);
     97   if (CC != SOF_OTHER)
     98     return true;
     99 
    100   // In C, functions with no attributes never need to be mangled. Fastpath them.
    101   if (!getASTContext().getLangOpts().CPlusPlus && !D->hasAttrs())
    102     return false;
    103 
    104   // Any decl can be declared with __asm("foo") on it, and this takes precedence
    105   // over all other naming in the .o file.
    106   if (D->hasAttr<AsmLabelAttr>())
    107     return true;
    108 
    109   return shouldMangleCXXName(D);
    110 }
    111 
    112 void MangleContext::mangleName(const NamedDecl *D, raw_ostream &Out) {
    113   // Any decl can be declared with __asm("foo") on it, and this takes precedence
    114   // over all other naming in the .o file.
    115   if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
    116     // If we have an asm name, then we use it as the mangling.
    117 
    118     // Adding the prefix can cause problems when one file has a "foo" and
    119     // another has a "\01foo". That is known to happen on ELF with the
    120     // tricks normally used for producing aliases (PR9177). Fortunately the
    121     // llvm mangler on ELF is a nop, so we can just avoid adding the \01
    122     // marker.  We also avoid adding the marker if this is an alias for an
    123     // LLVM intrinsic.
    124     StringRef UserLabelPrefix =
    125         getASTContext().getTargetInfo().getUserLabelPrefix();
    126     if (!UserLabelPrefix.empty() && !ALA->getLabel().startswith("llvm."))
    127       Out << '\01'; // LLVM IR Marker for __asm("foo")
    128 
    129     Out << ALA->getLabel();
    130     return;
    131   }
    132 
    133   const ASTContext &ASTContext = getASTContext();
    134   StdOrFastCC CC = getStdOrFastCallMangling(ASTContext, D);
    135   bool MCXX = shouldMangleCXXName(D);
    136   const TargetInfo &TI = Context.getTargetInfo();
    137   if (CC == SOF_OTHER || (MCXX && TI.getCXXABI() == TargetCXXABI::Microsoft)) {
    138     mangleCXXName(D, Out);
    139     return;
    140   }
    141 
    142   Out << '\01';
    143   if (CC == SOF_STD)
    144     Out << '_';
    145   else
    146     Out << '@';
    147 
    148   if (!MCXX)
    149     Out << D->getIdentifier()->getName();
    150   else
    151     mangleCXXName(D, Out);
    152 
    153   const FunctionDecl *FD = cast<FunctionDecl>(D);
    154   const FunctionType *FT = FD->getType()->castAs<FunctionType>();
    155   const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT);
    156   Out << '@';
    157   if (!Proto) {
    158     Out << '0';
    159     return;
    160   }
    161   assert(!Proto->isVariadic());
    162   unsigned ArgWords = 0;
    163   if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
    164     if (!MD->isStatic())
    165       ++ArgWords;
    166   for (const auto &AT : Proto->param_types())
    167     // Size should be aligned to DWORD boundary
    168     ArgWords += llvm::RoundUpToAlignment(ASTContext.getTypeSize(AT), 32) / 32;
    169   Out << 4 * ArgWords;
    170 }
    171 
    172 void MangleContext::mangleGlobalBlock(const BlockDecl *BD,
    173                                       const NamedDecl *ID,
    174                                       raw_ostream &Out) {
    175   unsigned discriminator = getBlockId(BD, false);
    176   if (ID) {
    177     if (shouldMangleDeclName(ID))
    178       mangleName(ID, Out);
    179     else {
    180       Out << ID->getIdentifier()->getName();
    181     }
    182   }
    183   if (discriminator == 0)
    184     Out << "_block_invoke";
    185   else
    186     Out << "_block_invoke_" << discriminator+1;
    187 }
    188 
    189 void MangleContext::mangleCtorBlock(const CXXConstructorDecl *CD,
    190                                     CXXCtorType CT, const BlockDecl *BD,
    191                                     raw_ostream &ResStream) {
    192   SmallString<64> Buffer;
    193   llvm::raw_svector_ostream Out(Buffer);
    194   mangleCXXCtor(CD, CT, Out);
    195   Out.flush();
    196   mangleFunctionBlock(*this, Buffer, BD, ResStream);
    197 }
    198 
    199 void MangleContext::mangleDtorBlock(const CXXDestructorDecl *DD,
    200                                     CXXDtorType DT, const BlockDecl *BD,
    201                                     raw_ostream &ResStream) {
    202   SmallString<64> Buffer;
    203   llvm::raw_svector_ostream Out(Buffer);
    204   mangleCXXDtor(DD, DT, Out);
    205   Out.flush();
    206   mangleFunctionBlock(*this, Buffer, BD, ResStream);
    207 }
    208 
    209 void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD,
    210                                 raw_ostream &Out) {
    211   assert(!isa<CXXConstructorDecl>(DC) && !isa<CXXDestructorDecl>(DC));
    212 
    213   SmallString<64> Buffer;
    214   llvm::raw_svector_ostream Stream(Buffer);
    215   if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC)) {
    216     mangleObjCMethodName(Method, Stream);
    217   } else {
    218     const NamedDecl *ND = cast<NamedDecl>(DC);
    219     if (!shouldMangleDeclName(ND) && ND->getIdentifier())
    220       Stream << ND->getIdentifier()->getName();
    221     else {
    222       // FIXME: We were doing a mangleUnqualifiedName() before, but that's
    223       // a private member of a class that will soon itself be private to the
    224       // Itanium C++ ABI object. What should we do now? Right now, I'm just
    225       // calling the mangleName() method on the MangleContext; is there a
    226       // better way?
    227       mangleName(ND, Stream);
    228     }
    229   }
    230   Stream.flush();
    231   mangleFunctionBlock(*this, Buffer, BD, Out);
    232 }
    233 
    234 void MangleContext::mangleObjCMethodName(const ObjCMethodDecl *MD,
    235                                          raw_ostream &Out) {
    236   SmallString<64> Name;
    237   llvm::raw_svector_ostream OS(Name);
    238 
    239   const ObjCContainerDecl *CD =
    240   dyn_cast<ObjCContainerDecl>(MD->getDeclContext());
    241   assert (CD && "Missing container decl in GetNameForMethod");
    242   OS << (MD->isInstanceMethod() ? '-' : '+') << '[' << CD->getName();
    243   if (const ObjCCategoryImplDecl *CID = dyn_cast<ObjCCategoryImplDecl>(CD))
    244     OS << '(' << *CID << ')';
    245   OS << ' ';
    246   MD->getSelector().print(OS);
    247   OS << ']';
    248 
    249   Out << OS.str().size() << OS.str();
    250 }
    251