lib/Target/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/Target/Mangler.h"
  15 #include "llvm/DerivedTypes.h"
  16 #include "llvm/Function.h"
  17 #include "llvm/Target/TargetData.h"
  18 #include "llvm/MC/MCAsmInfo.h"
  19 #include "llvm/MC/MCContext.h"
  20 #include "llvm/Support/raw_ostream.h"
  21 #include "llvm/ADT/SmallString.h"
  22 #include "llvm/ADT/Twine.h"
  23 using namespace llvm;
  24
  25 static bool isAcceptableChar(char C, bool AllowPeriod) {
  26   if ((C < 'a' || C > 'z') &&
  27       (C < 'A' || C > 'Z') &&
  28       (C < '0' || C > '9') &&
  29       C != '_' && C != '$' && C != '@' &&
  30       !(AllowPeriod && C == '.'))
  31     return false;
  32   return true;
  33 }
  34
  35 static char HexDigit(int V) {
  36   return V < 10 ? V+'0' : V+'A'-10;
  37 }
  38
  39 static void MangleLetter(SmallVectorImpl<char> &OutName, unsigned char C) {
  40   OutName.push_back('_');
  41   OutName.push_back(HexDigit(C >> 4));
  42   OutName.push_back(HexDigit(C & 15));
  43   OutName.push_back('_');
  44 }
  45
  46 /// NameNeedsEscaping - Return true if the identifier \arg Str needs quotes
  47 /// for this assembler.
  48 static bool NameNeedsEscaping(StringRef Str, const MCAsmInfo &MAI) {
  49   assert(!Str.empty() && "Cannot create an empty MCSymbol");
  50
  51   // If the first character is a number and the target does not allow this, we
  52   // need quotes.
  53   if (!MAI.doesAllowNameToStartWithDigit() && Str[0] >= '0' && Str[0] <= '9')
  54     return true;
  55
  56   // If any of the characters in the string is an unacceptable character, force
  57   // quotes.
  58   bool AllowPeriod = MAI.doesAllowPeriodsInName();
  59   for (unsigned i = 0, e = Str.size(); i != e; ++i)
  60     if (!isAcceptableChar(Str[i], AllowPeriod))
  61       return true;
  62   return false;
  63 }
  64
  65 /// appendMangledName - Add the specified string in mangled form if it uses
  66 /// any unusual characters.
  67 static void appendMangledName(SmallVectorImpl<char> &OutName, StringRef Str,
  68                               const MCAsmInfo &MAI) {
  69   // The first character is not allowed to be a number unless the target
  70   // explicitly allows it.
  71   if (!MAI.doesAllowNameToStartWithDigit() && Str[0] >= '0' && Str[0] <= '9') {
  72     MangleLetter(OutName, Str[0]);
  73     Str = Str.substr(1);
  74   }
  75
  76   bool AllowPeriod = MAI.doesAllowPeriodsInName();
  77   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
  78     if (!isAcceptableChar(Str[i], AllowPeriod))
  79       MangleLetter(OutName, Str[i]);
  80     else
  81       OutName.push_back(Str[i]);
  82   }
  83 }
  84
  85
  86 /// appendMangledQuotedName - On systems that support quoted symbols, we still
  87 /// have to escape some (obscure) characters like " and \n which would break the
  88 /// assembler's lexing.
  89 static void appendMangledQuotedName(SmallVectorImpl<char> &OutName,
  90                                    StringRef Str) {
  91   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
  92     if (Str[i] == '"' || Str[i] == '\n')
  93       MangleLetter(OutName, Str[i]);
  94     else
  95       OutName.push_back(Str[i]);
  96   }
  97 }
  98
  99
 100 /// getNameWithPrefix - Fill OutName with the name of the appropriate prefix
 101 /// and the specified name as the global variable name.  GVName must not be
 102 /// empty.
 103 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
 104                                 const Twine &GVName, ManglerPrefixTy PrefixTy) {
 105   SmallString<256> TmpData;
 106   StringRef Name = GVName.toStringRef(TmpData);
 107   assert(!Name.empty() && "getNameWithPrefix requires non-empty name");
 108
 109   const MCAsmInfo &MAI = Context.getAsmInfo();
 110
 111   // If the global name is not led with \1, add the appropriate prefixes.
 112   if (Name[0] == '\1') {
 113     Name = Name.substr(1);
 114   } else {
 115     if (PrefixTy == Mangler::Private) {
 116       const char *Prefix = MAI.getPrivateGlobalPrefix();
 117       OutName.append(Prefix, Prefix+strlen(Prefix));
 118     } else if (PrefixTy == Mangler::LinkerPrivate) {
 119       const char *Prefix = MAI.getLinkerPrivateGlobalPrefix();
 120       OutName.append(Prefix, Prefix+strlen(Prefix));
 121     }
 122
 123     const char *Prefix = MAI.getGlobalPrefix();
 124     if (Prefix[0] == 0)
 125       ; // Common noop, no prefix.
 126     else if (Prefix[1] == 0)
 127       OutName.push_back(Prefix[0]);  // Common, one character prefix.
 128     else
 129       OutName.append(Prefix, Prefix+strlen(Prefix)); // Arbitrary length prefix.
 130   }
 131
 132   // If this is a simple string that doesn't need escaping, just append it.
 133   if (!NameNeedsEscaping(Name, MAI) ||
 134       // If quotes are supported, they can be used unless the string contains
 135       // a quote or newline.
 136       (MAI.doesAllowQuotesInName() &&
 137        Name.find_first_of("\n\"") == StringRef::npos)) {
 138     OutName.append(Name.begin(), Name.end());
 139     return;
 140   }
 141
 142   // On systems that do not allow quoted names, we need to mangle most
 143   // strange characters.
 144   if (!MAI.doesAllowQuotesInName())
 145     return appendMangledName(OutName, Name, MAI);
 146
 147   // Okay, the system allows quoted strings.  We can quote most anything, the
 148   // only characters that need escaping are " and \n.
 149   assert(Name.find_first_of("\n\"") != StringRef::npos);
 150   return appendMangledQuotedName(OutName, Name);
 151 }
 152
 153 /// AddFastCallStdCallSuffix - Microsoft fastcall and stdcall functions require
 154 /// a suffix on their name indicating the number of words of arguments they
 155 /// take.
 156 static void AddFastCallStdCallSuffix(SmallVectorImpl<char> &OutName,
 157                                      const Function *F, const TargetData &TD) {
 158   // Calculate arguments size total.
 159   unsigned ArgWords = 0;
 160   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
 161        AI != AE; ++AI) {
 162     const Type *Ty = AI->getType();
 163     // 'Dereference' type in case of byval parameter attribute
 164     if (AI->hasByValAttr())
 165       Ty = cast<PointerType>(Ty)->getElementType();
 166     // Size should be aligned to DWORD boundary
 167     ArgWords += ((TD.getTypeAllocSize(Ty) + 3)/4)*4;
 168   }
 169
 170   raw_svector_ostream(OutName) << '@' << ArgWords;
 171 }
 172
 173
 174 /// getNameWithPrefix - Fill OutName with the name of the appropriate prefix
 175 /// and the specified global variable's name.  If the global variable doesn't
 176 /// have a name, this fills in a unique name for the global.
 177 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
 178                                 const GlobalValue *GV,
 179                                 bool isImplicitlyPrivate) {
 180   ManglerPrefixTy PrefixTy = Mangler::Default;
 181   if (GV->hasPrivateLinkage() || isImplicitlyPrivate)
 182     PrefixTy = Mangler::Private;
 183   else if (GV->hasLinkerPrivateLinkage() || GV->hasLinkerPrivateWeakLinkage() ||
 184            GV->hasLinkerPrivateWeakDefAutoLinkage())
 185     PrefixTy = Mangler::LinkerPrivate;
 186
 187   // If this global has a name, handle it simply.
 188   if (GV->hasName()) {
 189     getNameWithPrefix(OutName, GV->getName(), PrefixTy);
 190   } else {
 191     // Get the ID for the global, assigning a new one if we haven't got one
 192     // already.
 193     unsigned &ID = AnonGlobalIDs[GV];
 194     if (ID == 0) ID = NextAnonGlobalID++;
 195
 196     // Must mangle the global into a unique ID.
 197     getNameWithPrefix(OutName, "__unnamed_" + Twine(ID), PrefixTy);
 198   }
 199
 200   // If we are supposed to add a microsoft-style suffix for stdcall/fastcall,
 201   // add it.
 202   if (Context.getAsmInfo().hasMicrosoftFastStdCallMangling()) {
 203     if (const Function *F = dyn_cast<Function>(GV)) {
 204       CallingConv::ID CC = F->getCallingConv();
 205
 206       // fastcall functions need to start with @.
 207       // FIXME: This logic seems unlikely to be right.
 208       if (CC == CallingConv::X86_FastCall) {
 209         if (OutName[0] == '_')
 210           OutName[0] = '@';
 211         else
 212           OutName.insert(OutName.begin(), '@');
 213       }
 214
 215       // fastcall and stdcall functions usually need @42 at the end to specify
 216       // the argument info.
 217       const FunctionType *FT = F->getFunctionType();
 218       if ((CC == CallingConv::X86_FastCall || CC == CallingConv::X86_StdCall) &&
 219           // "Pure" variadic functions do not receive @0 suffix.
 220           (!FT->isVarArg() || FT->getNumParams() == 0 ||
 221            (FT->getNumParams() == 1 && F->hasStructRetAttr())))
 222         AddFastCallStdCallSuffix(OutName, F, TD);
 223     }
 224   }
 225 }
 226
 227 /// getSymbol - Return the MCSymbol for the specified global value.  This
 228 /// symbol is the main label that is the address of the global.
 229 MCSymbol *Mangler::getSymbol(const GlobalValue *GV) {
 230   SmallString<60> NameStr;
 231   getNameWithPrefix(NameStr, GV, false);
 232   return Context.GetOrCreateSymbol(NameStr.str());
 233 }
 234
 235