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