lib/IR/Mangler.cpp

   1 //===-- Mangler.cpp - Self-contained c/asm llvm name mangler --------------===//
   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 // Unified name mangler for assembly backends.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/IR/Mangler.h"
  15 #include "llvm/ADT/SmallString.h"
  16 #include "llvm/ADT/Triple.h"
  17 #include "llvm/ADT/Twine.h"
  18 #include "llvm/IR/DataLayout.h"
  19 #include "llvm/IR/DerivedTypes.h"
  20 #include "llvm/IR/Function.h"
  21 #include "llvm/IR/Module.h"
  22 #include "llvm/Support/raw_ostream.h"
  23 using namespace llvm;
  24
  25 namespace {
  26 enum ManglerPrefixTy {
  27   Default,      ///< Emit default string before each symbol.
  28   Private,      ///< Emit "private" prefix before each symbol.
  29   LinkerPrivate ///< Emit "linker private" prefix before each symbol.
  30 };
  31 }
  32
  33 static void getNameWithPrefixImpl(raw_ostream &OS, const Twine &GVName,
  34                                   ManglerPrefixTy PrefixTy,
  35                                   const DataLayout &DL, char Prefix) {
  36   SmallString<256> TmpData;
  37   StringRef Name = GVName.toStringRef(TmpData);
  38   assert(!Name.empty() && "getNameWithPrefix requires non-empty name");
  39
  40   // No need to do anything special if the global has the special "do not
  41   // mangle" flag in the name.
  42   if (Name[0] == '\1') {
  43     OS << Name.substr(1);
  44     return;
  45   }
  46
  47   if (PrefixTy == Private)
  48     OS << DL.getPrivateGlobalPrefix();
  49   else if (PrefixTy == LinkerPrivate)
  50     OS << DL.getLinkerPrivateGlobalPrefix();
  51
  52   if (Prefix != '\0')
  53     OS << Prefix;
  54
  55   // If this is a simple string that doesn't need escaping, just append it.
  56   OS << Name;
  57 }
  58
  59 static void getNameWithPrefixImpl(raw_ostream &OS, const Twine &GVName,
  60                                   const DataLayout &DL,
  61                                   ManglerPrefixTy PrefixTy) {
  62   char Prefix = DL.getGlobalPrefix();
  63   return getNameWithPrefixImpl(OS, GVName, PrefixTy, DL, Prefix);
  64 }
  65
  66 void Mangler::getNameWithPrefix(raw_ostream &OS, const Twine &GVName,
  67                                 const DataLayout &DL) {
  68   return getNameWithPrefixImpl(OS, GVName, DL, Default);
  69 }
  70
  71 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
  72                                 const Twine &GVName, const DataLayout &DL) {
  73   raw_svector_ostream OS(OutName);
  74   char Prefix = DL.getGlobalPrefix();
  75   return getNameWithPrefixImpl(OS, GVName, Default, DL, Prefix);
  76 }
  77
  78 static bool hasByteCountSuffix(CallingConv::ID CC) {
  79   switch (CC) {
  80   case CallingConv::X86_FastCall:
  81   case CallingConv::X86_StdCall:
  82   case CallingConv::X86_VectorCall:
  83     return true;
  84   default:
  85     return false;
  86   }
  87 }
  88
  89 /// Microsoft fastcall and stdcall functions require a suffix on their name
  90 /// indicating the number of words of arguments they take.
  91 static void addByteCountSuffix(raw_ostream &OS, const Function *F,
  92                                const DataLayout &DL) {
  93   // Calculate arguments size total.
  94   unsigned ArgWords = 0;
  95   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
  96        AI != AE; ++AI) {
  97     Type *Ty = AI->getType();
  98     // 'Dereference' type in case of byval or inalloca parameter attribute.
  99     if (AI->hasByValOrInAllocaAttr())
 100       Ty = cast<PointerType>(Ty)->getElementType();
 101     // Size should be aligned to pointer size.
 102     unsigned PtrSize = DL.getPointerSize();
 103     ArgWords += alignTo(DL.getTypeAllocSize(Ty), PtrSize);
 104   }
 105
 106   OS << '@' << ArgWords;
 107 }
 108
 109 void Mangler::getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV,
 110                                 bool CannotUsePrivateLabel) const {
 111   ManglerPrefixTy PrefixTy = Default;
 112   if (GV->hasPrivateLinkage()) {
 113     if (CannotUsePrivateLabel)
 114       PrefixTy = LinkerPrivate;
 115     else
 116       PrefixTy = Private;
 117   }
 118
 119   const DataLayout &DL = GV->getParent()->getDataLayout();
 120   if (!GV->hasName()) {
 121     // Get the ID for the global, assigning a new one if we haven't got one
 122     // already.
 123     unsigned &ID = AnonGlobalIDs[GV];
 124     if (ID == 0)
 125       ID = AnonGlobalIDs.size();
 126
 127     // Must mangle the global into a unique ID.
 128     getNameWithPrefixImpl(OS, "__unnamed_" + Twine(ID), DL, PrefixTy);
 129     return;
 130   }
 131
 132   StringRef Name = GV->getName();
 133   char Prefix = DL.getGlobalPrefix();
 134
 135   // Mangle functions with Microsoft calling conventions specially.  Only do
 136   // this mangling for x86_64 vectorcall and 32-bit x86.
 137   const Function *MSFunc = dyn_cast<Function>(GV);
 138   if (Name.startswith("\01"))
 139     MSFunc = nullptr; // Don't mangle when \01 is present.
 140   CallingConv::ID CC =
 141       MSFunc ? MSFunc->getCallingConv() : (unsigned)CallingConv::C;
 142   if (!DL.hasMicrosoftFastStdCallMangling() &&
 143       CC != CallingConv::X86_VectorCall)
 144     MSFunc = nullptr;
 145   if (MSFunc) {
 146     if (CC == CallingConv::X86_FastCall)
 147       Prefix = '@'; // fastcall functions have an @ prefix instead of _.
 148     else if (CC == CallingConv::X86_VectorCall)
 149       Prefix = '\0'; // vectorcall functions have no prefix.
 150   }
 151
 152   getNameWithPrefixImpl(OS, Name, PrefixTy, DL, Prefix);
 153
 154   if (!MSFunc)
 155     return;
 156
 157   // If we are supposed to add a microsoft-style suffix for stdcall, fastcall,
 158   // or vectorcall, add it.  These functions have a suffix of @N where N is the
 159   // cumulative byte size of all of the parameters to the function in decimal.
 160   if (CC == CallingConv::X86_VectorCall)
 161     OS << '@'; // vectorcall functions use a double @ suffix.
 162   FunctionType *FT = MSFunc->getFunctionType();
 163   if (hasByteCountSuffix(CC) &&
 164       // "Pure" variadic functions do not receive @0 suffix.
 165       (!FT->isVarArg() || FT->getNumParams() == 0 ||
 166        (FT->getNumParams() == 1 && MSFunc->hasStructRetAttr())))
 167     addByteCountSuffix(OS, MSFunc, DL);
 168 }
 169
 170 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
 171                                 const GlobalValue *GV,
 172                                 bool CannotUsePrivateLabel) const {
 173   raw_svector_ostream OS(OutName);
 174   getNameWithPrefix(OS, GV, CannotUsePrivateLabel);
 175 }
 176
 177 void llvm::emitLinkerFlagsForGlobalCOFF(raw_ostream &OS, const GlobalValue *GV,
 178                                         const Triple &TT, Mangler &Mangler) {
 179   if (!GV->hasDLLExportStorageClass() || GV->isDeclaration())
 180     return;
 181
 182   if (TT.isKnownWindowsMSVCEnvironment())
 183     OS << " /EXPORT:";
 184   else
 185     OS << " -export:";
 186
 187   if (TT.isWindowsGNUEnvironment() || TT.isWindowsCygwinEnvironment()) {
 188     std::string Flag;
 189     raw_string_ostream FlagOS(Flag);
 190     Mangler.getNameWithPrefix(FlagOS, GV, false);
 191     FlagOS.flush();
 192     if (Flag[0] == GV->getParent()->getDataLayout().getGlobalPrefix())
 193       OS << Flag.substr(1);
 194     else
 195       OS << Flag;
 196   } else {
 197     Mangler.getNameWithPrefix(OS, GV, false);
 198   }
 199
 200   if (!GV->getValueType()->isFunctionTy()) {
 201     if (TT.isKnownWindowsMSVCEnvironment())
 202       OS << ",DATA";
 203     else
 204       OS << ",data";
 205   }
 206 }