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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 CCMangling {
     53   CCM_Other,
     54   CCM_Fast,
     55   CCM_Vector,
     56   CCM_Std
     57 };
     58 
     59 static bool isExternC(const NamedDecl *ND) {
     60   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))
     61     return FD->isExternC();
     62   return cast<VarDecl>(ND)->isExternC();
     63 }
     64 
     65 static CCMangling getCallingConvMangling(const ASTContext &Context,
     66                                          const NamedDecl *ND) {
     67   const TargetInfo &TI = Context.getTargetInfo();
     68   const llvm::Triple &Triple = TI.getTriple();
     69   if (!Triple.isOSWindows() ||
     70       !(Triple.getArch() == llvm::Triple::x86 ||
     71         Triple.getArch() == llvm::Triple::x86_64))
     72     return CCM_Other;
     73 
     74   if (Context.getLangOpts().CPlusPlus && !isExternC(ND) &&
     75       TI.getCXXABI() == TargetCXXABI::Microsoft)
     76     return CCM_Other;
     77 
     78   const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND);
     79   if (!FD)
     80     return CCM_Other;
     81   QualType T = FD->getType();
     82 
     83   const FunctionType *FT = T->castAs<FunctionType>();
     84 
     85   CallingConv CC = FT->getCallConv();
     86   switch (CC) {
     87   default:
     88     return CCM_Other;
     89   case CC_X86FastCall:
     90     return CCM_Fast;
     91   case CC_X86StdCall:
     92     return CCM_Std;
     93   case CC_X86VectorCall:
     94     return CCM_Vector;
     95   }
     96 }
     97 
     98 bool MangleContext::shouldMangleDeclName(const NamedDecl *D) {
     99   const ASTContext &ASTContext = getASTContext();
    100 
    101   CCMangling CC = getCallingConvMangling(ASTContext, D);
    102   if (CC != CCM_Other)
    103     return true;
    104 
    105   // In C, functions with no attributes never need to be mangled. Fastpath them.
    106   if (!getASTContext().getLangOpts().CPlusPlus && !D->hasAttrs())
    107     return false;
    108 
    109   // Any decl can be declared with __asm("foo") on it, and this takes precedence
    110   // over all other naming in the .o file.
    111   if (D->hasAttr<AsmLabelAttr>())
    112     return true;
    113 
    114   return shouldMangleCXXName(D);
    115 }
    116 
    117 void MangleContext::mangleName(const NamedDecl *D, raw_ostream &Out) {
    118   // Any decl can be declared with __asm("foo") on it, and this takes precedence
    119   // over all other naming in the .o file.
    120   if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
    121     // If we have an asm name, then we use it as the mangling.
    122 
    123     // Adding the prefix can cause problems when one file has a "foo" and
    124     // another has a "\01foo". That is known to happen on ELF with the
    125     // tricks normally used for producing aliases (PR9177). Fortunately the
    126     // llvm mangler on ELF is a nop, so we can just avoid adding the \01
    127     // marker.  We also avoid adding the marker if this is an alias for an
    128     // LLVM intrinsic.
    129     char GlobalPrefix =
    130         getASTContext().getTargetInfo().getDataLayout().getGlobalPrefix();
    131     if (GlobalPrefix && !ALA->getLabel().startswith("llvm."))
    132       Out << '\01'; // LLVM IR Marker for __asm("foo")
    133 
    134     Out << ALA->getLabel();
    135     return;
    136   }
    137 
    138   const ASTContext &ASTContext = getASTContext();
    139   CCMangling CC = getCallingConvMangling(ASTContext, D);
    140   bool MCXX = shouldMangleCXXName(D);
    141   const TargetInfo &TI = Context.getTargetInfo();
    142   if (CC == CCM_Other || (MCXX && TI.getCXXABI() == TargetCXXABI::Microsoft)) {
    143     if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D))
    144       mangleObjCMethodName(OMD, Out);
    145     else
    146       mangleCXXName(D, Out);
    147     return;
    148   }
    149 
    150   Out << '\01';
    151   if (CC == CCM_Std)
    152     Out << '_';
    153   else if (CC == CCM_Fast)
    154     Out << '@';
    155 
    156   if (!MCXX)
    157     Out << D->getIdentifier()->getName();
    158   else if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D))
    159     mangleObjCMethodName(OMD, Out);
    160   else
    161     mangleCXXName(D, Out);
    162 
    163   const FunctionDecl *FD = cast<FunctionDecl>(D);
    164   const FunctionType *FT = FD->getType()->castAs<FunctionType>();
    165   const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT);
    166   if (CC == CCM_Vector)
    167     Out << '@';
    168   Out << '@';
    169   if (!Proto) {
    170     Out << '0';
    171     return;
    172   }
    173   assert(!Proto->isVariadic());
    174   unsigned ArgWords = 0;
    175   if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
    176     if (!MD->isStatic())
    177       ++ArgWords;
    178   for (const auto &AT : Proto->param_types())
    179     // Size should be aligned to pointer size.
    180     ArgWords +=
    181         llvm::alignTo(ASTContext.getTypeSize(AT), TI.getPointerWidth(0)) /
    182         TI.getPointerWidth(0);
    183   Out << ((TI.getPointerWidth(0) / 8) * ArgWords);
    184 }
    185 
    186 void MangleContext::mangleGlobalBlock(const BlockDecl *BD,
    187                                       const NamedDecl *ID,
    188                                       raw_ostream &Out) {
    189   unsigned discriminator = getBlockId(BD, false);
    190   if (ID) {
    191     if (shouldMangleDeclName(ID))
    192       mangleName(ID, Out);
    193     else {
    194       Out << ID->getIdentifier()->getName();
    195     }
    196   }
    197   if (discriminator == 0)
    198     Out << "_block_invoke";
    199   else
    200     Out << "_block_invoke_" << discriminator+1;
    201 }
    202 
    203 void MangleContext::mangleCtorBlock(const CXXConstructorDecl *CD,
    204                                     CXXCtorType CT, const BlockDecl *BD,
    205                                     raw_ostream &ResStream) {
    206   SmallString<64> Buffer;
    207   llvm::raw_svector_ostream Out(Buffer);
    208   mangleCXXCtor(CD, CT, Out);
    209   mangleFunctionBlock(*this, Buffer, BD, ResStream);
    210 }
    211 
    212 void MangleContext::mangleDtorBlock(const CXXDestructorDecl *DD,
    213                                     CXXDtorType DT, const BlockDecl *BD,
    214                                     raw_ostream &ResStream) {
    215   SmallString<64> Buffer;
    216   llvm::raw_svector_ostream Out(Buffer);
    217   mangleCXXDtor(DD, DT, Out);
    218   mangleFunctionBlock(*this, Buffer, BD, ResStream);
    219 }
    220 
    221 void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD,
    222                                 raw_ostream &Out) {
    223   assert(!isa<CXXConstructorDecl>(DC) && !isa<CXXDestructorDecl>(DC));
    224 
    225   SmallString<64> Buffer;
    226   llvm::raw_svector_ostream Stream(Buffer);
    227   if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC)) {
    228     mangleObjCMethodName(Method, Stream);
    229   } else {
    230     assert((isa<NamedDecl>(DC) || isa<BlockDecl>(DC)) &&
    231            "expected a NamedDecl or BlockDecl");
    232     if (isa<BlockDecl>(DC))
    233       for (; DC && isa<BlockDecl>(DC); DC = DC->getParent())
    234         (void) getBlockId(cast<BlockDecl>(DC), true);
    235     assert((isa<TranslationUnitDecl>(DC) || isa<NamedDecl>(DC)) &&
    236            "expected a TranslationUnitDecl or a NamedDecl");
    237     if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC))
    238       mangleCtorBlock(CD, /*CT*/ Ctor_Complete, BD, Out);
    239     else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC))
    240       mangleDtorBlock(DD, /*DT*/ Dtor_Complete, BD, Out);
    241     else if (auto ND = dyn_cast<NamedDecl>(DC)) {
    242       if (!shouldMangleDeclName(ND) && ND->getIdentifier())
    243         Stream << ND->getIdentifier()->getName();
    244       else {
    245         // FIXME: We were doing a mangleUnqualifiedName() before, but that's
    246         // a private member of a class that will soon itself be private to the
    247         // Itanium C++ ABI object. What should we do now? Right now, I'm just
    248         // calling the mangleName() method on the MangleContext; is there a
    249         // better way?
    250         mangleName(ND, Stream);
    251       }
    252     }
    253   }
    254   mangleFunctionBlock(*this, Buffer, BD, Out);
    255 }
    256 
    257 void MangleContext::mangleObjCMethodNameWithoutSize(const ObjCMethodDecl *MD,
    258                                                     raw_ostream &OS) {
    259   const ObjCContainerDecl *CD =
    260   dyn_cast<ObjCContainerDecl>(MD->getDeclContext());
    261   assert (CD && "Missing container decl in GetNameForMethod");
    262   OS << (MD->isInstanceMethod() ? '-' : '+') << '[' << CD->getName();
    263   if (const ObjCCategoryImplDecl *CID = dyn_cast<ObjCCategoryImplDecl>(CD))
    264     OS << '(' << *CID << ')';
    265   OS << ' ';
    266   MD->getSelector().print(OS);
    267   OS << ']';
    268 }
    269 
    270 void MangleContext::mangleObjCMethodName(const ObjCMethodDecl *MD,
    271                                          raw_ostream &Out) {
    272   SmallString<64> Name;
    273   llvm::raw_svector_ostream OS(Name);
    274 
    275   mangleObjCMethodNameWithoutSize(MD, OS);
    276   Out << OS.str().size() << OS.str();
    277 }
    278