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 (DL.doNotMangleLeadingQuestionMark() && Name[0] == '?')
  48     Prefix = '\0';
  49
  50   if (PrefixTy == Private)
  51     OS << DL.getPrivateGlobalPrefix();
  52   else if (PrefixTy == LinkerPrivate)
  53     OS << DL.getLinkerPrivateGlobalPrefix();
  54
  55   if (Prefix != '\0')
  56     OS << Prefix;
  57
  58   // If this is a simple string that doesn't need escaping, just append it.
  59   OS << Name;
  60 }
  61
  62 static void getNameWithPrefixImpl(raw_ostream &OS, const Twine &GVName,
  63                                   const DataLayout &DL,
  64                                   ManglerPrefixTy PrefixTy) {
  65   char Prefix = DL.getGlobalPrefix();
  66   return getNameWithPrefixImpl(OS, GVName, PrefixTy, DL, Prefix);
  67 }
  68
  69 void Mangler::getNameWithPrefix(raw_ostream &OS, const Twine &GVName,
  70                                 const DataLayout &DL) {
  71   return getNameWithPrefixImpl(OS, GVName, DL, Default);
  72 }
  73
  74 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
  75                                 const Twine &GVName, const DataLayout &DL) {
  76   raw_svector_ostream OS(OutName);
  77   char Prefix = DL.getGlobalPrefix();
  78   return getNameWithPrefixImpl(OS, GVName, Default, DL, Prefix);
  79 }
  80
  81 static bool hasByteCountSuffix(CallingConv::ID CC) {
  82   switch (CC) {
  83   case CallingConv::X86_FastCall:
  84   case CallingConv::X86_StdCall:
  85   case CallingConv::X86_VectorCall:
  86     return true;
  87   default:
  88     return false;
  89   }
  90 }
  91
  92 /// Microsoft fastcall and stdcall functions require a suffix on their name
  93 /// indicating the number of words of arguments they take.
  94 static void addByteCountSuffix(raw_ostream &OS, const Function *F,
  95                                const DataLayout &DL) {
  96   // Calculate arguments size total.
  97   unsigned ArgWords = 0;
  98   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
  99        AI != AE; ++AI) {
 100     Type *Ty = AI->getType();
 101     // 'Dereference' type in case of byval or inalloca parameter attribute.
 102     if (AI->hasByValOrInAllocaAttr())
 103       Ty = cast<PointerType>(Ty)->getElementType();
 104     // Size should be aligned to pointer size.
 105     unsigned PtrSize = DL.getPointerSize();
 106     ArgWords += alignTo(DL.getTypeAllocSize(Ty), PtrSize);
 107   }
 108
 109   OS << '@' << ArgWords;
 110 }
 111
 112 void Mangler::getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV,
 113                                 bool CannotUsePrivateLabel) const {
 114   ManglerPrefixTy PrefixTy = Default;
 115   if (GV->hasPrivateLinkage()) {
 116     if (CannotUsePrivateLabel)
 117       PrefixTy = LinkerPrivate;
 118     else
 119       PrefixTy = Private;
 120   }
 121
 122   const DataLayout &DL = GV->getParent()->getDataLayout();
 123   if (!GV->hasName()) {
 124     // Get the ID for the global, assigning a new one if we haven't got one
 125     // already.
 126     unsigned &ID = AnonGlobalIDs[GV];
 127     if (ID == 0)
 128       ID = AnonGlobalIDs.size();
 129
 130     // Must mangle the global into a unique ID.
 131     getNameWithPrefixImpl(OS, "__unnamed_" + Twine(ID), DL, PrefixTy);
 132     return;
 133   }
 134
 135   StringRef Name = GV->getName();
 136   char Prefix = DL.getGlobalPrefix();
 137
 138   // Mangle functions with Microsoft calling conventions specially.  Only do
 139   // this mangling for x86_64 vectorcall and 32-bit x86.
 140   const Function *MSFunc = dyn_cast<Function>(GV);
 141
 142   // Don't add byte count suffixes when '\01' or '?' are in the first
 143   // character.
 144   if (Name.startswith("\01") ||
 145       (DL.doNotMangleLeadingQuestionMark() && Name.startswith("?")))
 146     MSFunc = nullptr;
 147
 148   CallingConv::ID CC =
 149       MSFunc ? MSFunc->getCallingConv() : (unsigned)CallingConv::C;
 150   if (!DL.hasMicrosoftFastStdCallMangling() &&
 151       CC != CallingConv::X86_VectorCall)
 152     MSFunc = nullptr;
 153   if (MSFunc) {
 154     if (CC == CallingConv::X86_FastCall)
 155       Prefix = '@'; // fastcall functions have an @ prefix instead of _.
 156     else if (CC == CallingConv::X86_VectorCall)
 157       Prefix = '\0'; // vectorcall functions have no prefix.
 158   }
 159
 160   getNameWithPrefixImpl(OS, Name, PrefixTy, DL, Prefix);
 161
 162   if (!MSFunc)
 163     return;
 164
 165   // If we are supposed to add a microsoft-style suffix for stdcall, fastcall,
 166   // or vectorcall, add it.  These functions have a suffix of @N where N is the
 167   // cumulative byte size of all of the parameters to the function in decimal.
 168   if (CC == CallingConv::X86_VectorCall)
 169     OS << '@'; // vectorcall functions use a double @ suffix.
 170   FunctionType *FT = MSFunc->getFunctionType();
 171   if (hasByteCountSuffix(CC) &&
 172       // "Pure" variadic functions do not receive @0 suffix.
 173       (!FT->isVarArg() || FT->getNumParams() == 0 ||
 174        (FT->getNumParams() == 1 && MSFunc->hasStructRetAttr())))
 175     addByteCountSuffix(OS, MSFunc, DL);
 176 }
 177
 178 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
 179                                 const GlobalValue *GV,
 180                                 bool CannotUsePrivateLabel) const {
 181   raw_svector_ostream OS(OutName);
 182   getNameWithPrefix(OS, GV, CannotUsePrivateLabel);
 183 }
 184
 185 void llvm::emitLinkerFlagsForGlobalCOFF(raw_ostream &OS, const GlobalValue *GV,
 186                                         const Triple &TT, Mangler &Mangler) {
 187   if (!GV->hasDLLExportStorageClass() || GV->isDeclaration())
 188     return;
 189
 190   if (TT.isKnownWindowsMSVCEnvironment())
 191     OS << " /EXPORT:";
 192   else
 193     OS << " -export:";
 194
 195   if (TT.isWindowsGNUEnvironment() || TT.isWindowsCygwinEnvironment()) {
 196     std::string Flag;
 197     raw_string_ostream FlagOS(Flag);
 198     Mangler.getNameWithPrefix(FlagOS, GV, false);
 199     FlagOS.flush();
 200     if (Flag[0] == GV->getParent()->getDataLayout().getGlobalPrefix())
 201       OS << Flag.substr(1);
 202     else
 203       OS << Flag;
 204   } else {
 205     Mangler.getNameWithPrefix(OS, GV, false);
 206   }
 207
 208   if (!GV->getValueType()->isFunctionTy()) {
 209     if (TT.isKnownWindowsMSVCEnvironment())
 210       OS << ",DATA";
 211     else
 212       OS << ",data";
 213   }
 214 }
 215
 216 void llvm::emitLinkerFlagsForUsedCOFF(raw_ostream &OS, const GlobalValue *GV,
 217                                       const Triple &T, Mangler &M) {
 218   if (!T.isKnownWindowsMSVCEnvironment())
 219     return;
 220
 221   OS << " /INCLUDE:";
 222   M.getNameWithPrefix(OS, GV, false);
 223 }
 224