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, bool AllowUTF8) { 26 if ((C < 'a' || C > 'z') && 27 (C < 'A' || C > 'Z') && 28 (C < '0' || C > '9') && 29 C != '_' && C != '$' && C != '@' && 30 !(AllowPeriod && C == '.') && 31 !(AllowUTF8 && (C & 0x80))) 32 return false; 33 return true; 34 } 35 36 static char HexDigit(int V) { 37 return V < 10 ? V+'0' : V+'A'-10; 38 } 39 40 static void MangleLetter(SmallVectorImpl<char> &OutName, unsigned char C) { 41 OutName.push_back('_'); 42 OutName.push_back(HexDigit(C >> 4)); 43 OutName.push_back(HexDigit(C & 15)); 44 OutName.push_back('_'); 45 } 46 47 /// NameNeedsEscaping - Return true if the identifier \arg Str needs quotes 48 /// for this assembler. 49 static bool NameNeedsEscaping(StringRef Str, const MCAsmInfo &MAI) { 50 assert(!Str.empty() && "Cannot create an empty MCSymbol"); 51 52 // If the first character is a number and the target does not allow this, we 53 // need quotes. 54 if (!MAI.doesAllowNameToStartWithDigit() && Str[0] >= '0' && Str[0] <= '9') 55 return true; 56 57 // If any of the characters in the string is an unacceptable character, force 58 // quotes. 59 bool AllowPeriod = MAI.doesAllowPeriodsInName(); 60 bool AllowUTF8 = MAI.doesAllowUTF8(); 61 for (unsigned i = 0, e = Str.size(); i != e; ++i) 62 if (!isAcceptableChar(Str[i], AllowPeriod, AllowUTF8)) 63 return true; 64 return false; 65 } 66 67 /// appendMangledName - Add the specified string in mangled form if it uses 68 /// any unusual characters. 69 static void appendMangledName(SmallVectorImpl<char> &OutName, StringRef Str, 70 const MCAsmInfo &MAI) { 71 // The first character is not allowed to be a number unless the target 72 // explicitly allows it. 73 if (!MAI.doesAllowNameToStartWithDigit() && Str[0] >= '0' && Str[0] <= '9') { 74 MangleLetter(OutName, Str[0]); 75 Str = Str.substr(1); 76 } 77 78 bool AllowPeriod = MAI.doesAllowPeriodsInName(); 79 bool AllowUTF8 = MAI.doesAllowUTF8(); 80 for (unsigned i = 0, e = Str.size(); i != e; ++i) { 81 if (!isAcceptableChar(Str[i], AllowPeriod, AllowUTF8)) 82 MangleLetter(OutName, Str[i]); 83 else 84 OutName.push_back(Str[i]); 85 } 86 } 87 88 89 /// appendMangledQuotedName - On systems that support quoted symbols, we still 90 /// have to escape some (obscure) characters like " and \n which would break the 91 /// assembler's lexing. 92 static void appendMangledQuotedName(SmallVectorImpl<char> &OutName, 93 StringRef Str) { 94 for (unsigned i = 0, e = Str.size(); i != e; ++i) { 95 if (Str[i] == '"' || Str[i] == '\n') 96 MangleLetter(OutName, Str[i]); 97 else 98 OutName.push_back(Str[i]); 99 } 100 } 101 102 103 /// getNameWithPrefix - Fill OutName with the name of the appropriate prefix 104 /// and the specified name as the global variable name. GVName must not be 105 /// empty. 106 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName, 107 const Twine &GVName, ManglerPrefixTy PrefixTy) { 108 SmallString<256> TmpData; 109 StringRef Name = GVName.toStringRef(TmpData); 110 assert(!Name.empty() && "getNameWithPrefix requires non-empty name"); 111 112 const MCAsmInfo &MAI = Context.getAsmInfo(); 113 114 // If the global name is not led with \1, add the appropriate prefixes. 115 if (Name[0] == '\1') { 116 Name = Name.substr(1); 117 } else { 118 if (PrefixTy == Mangler::Private) { 119 const char *Prefix = MAI.getPrivateGlobalPrefix(); 120 OutName.append(Prefix, Prefix+strlen(Prefix)); 121 } else if (PrefixTy == Mangler::LinkerPrivate) { 122 const char *Prefix = MAI.getLinkerPrivateGlobalPrefix(); 123 OutName.append(Prefix, Prefix+strlen(Prefix)); 124 } 125 126 const char *Prefix = MAI.getGlobalPrefix(); 127 if (Prefix[0] == 0) 128 ; // Common noop, no prefix. 129 else if (Prefix[1] == 0) 130 OutName.push_back(Prefix[0]); // Common, one character prefix. 131 else 132 OutName.append(Prefix, Prefix+strlen(Prefix)); // Arbitrary length prefix. 133 } 134 135 // If this is a simple string that doesn't need escaping, just append it. 136 if (!NameNeedsEscaping(Name, MAI) || 137 // If quotes are supported, they can be used unless the string contains 138 // a quote or newline. 139 (MAI.doesAllowQuotesInName() && 140 Name.find_first_of("\n\"") == StringRef::npos)) { 141 OutName.append(Name.begin(), Name.end()); 142 return; 143 } 144 145 // On systems that do not allow quoted names, we need to mangle most 146 // strange characters. 147 if (!MAI.doesAllowQuotesInName()) 148 return appendMangledName(OutName, Name, MAI); 149 150 // Okay, the system allows quoted strings. We can quote most anything, the 151 // only characters that need escaping are " and \n. 152 assert(Name.find_first_of("\n\"") != StringRef::npos); 153 return appendMangledQuotedName(OutName, Name); 154 } 155 156 /// AddFastCallStdCallSuffix - Microsoft fastcall and stdcall functions require 157 /// a suffix on their name indicating the number of words of arguments they 158 /// take. 159 static void AddFastCallStdCallSuffix(SmallVectorImpl<char> &OutName, 160 const Function *F, const TargetData &TD) { 161 // Calculate arguments size total. 162 unsigned ArgWords = 0; 163 for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end(); 164 AI != AE; ++AI) { 165 Type *Ty = AI->getType(); 166 // 'Dereference' type in case of byval parameter attribute 167 if (AI->hasByValAttr()) 168 Ty = cast<PointerType>(Ty)->getElementType(); 169 // Size should be aligned to DWORD boundary 170 ArgWords += ((TD.getTypeAllocSize(Ty) + 3)/4)*4; 171 } 172 173 raw_svector_ostream(OutName) << '@' << ArgWords; 174 } 175 176 177 /// getNameWithPrefix - Fill OutName with the name of the appropriate prefix 178 /// and the specified global variable's name. If the global variable doesn't 179 /// have a name, this fills in a unique name for the global. 180 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName, 181 const GlobalValue *GV, 182 bool isImplicitlyPrivate) { 183 ManglerPrefixTy PrefixTy = Mangler::Default; 184 if (GV->hasPrivateLinkage() || isImplicitlyPrivate) 185 PrefixTy = Mangler::Private; 186 else if (GV->hasLinkerPrivateLinkage() || GV->hasLinkerPrivateWeakLinkage() || 187 GV->hasLinkerPrivateWeakDefAutoLinkage()) 188 PrefixTy = Mangler::LinkerPrivate; 189 190 // If this global has a name, handle it simply. 191 if (GV->hasName()) { 192 getNameWithPrefix(OutName, GV->getName(), PrefixTy); 193 } else { 194 // Get the ID for the global, assigning a new one if we haven't got one 195 // already. 196 unsigned &ID = AnonGlobalIDs[GV]; 197 if (ID == 0) ID = NextAnonGlobalID++; 198 199 // Must mangle the global into a unique ID. 200 getNameWithPrefix(OutName, "__unnamed_" + Twine(ID), PrefixTy); 201 } 202 203 // If we are supposed to add a microsoft-style suffix for stdcall/fastcall, 204 // add it. 205 if (Context.getAsmInfo().hasMicrosoftFastStdCallMangling()) { 206 if (const Function *F = dyn_cast<Function>(GV)) { 207 CallingConv::ID CC = F->getCallingConv(); 208 209 // fastcall functions need to start with @. 210 // FIXME: This logic seems unlikely to be right. 211 if (CC == CallingConv::X86_FastCall) { 212 if (OutName[0] == '_') 213 OutName[0] = '@'; 214 else 215 OutName.insert(OutName.begin(), '@'); 216 } 217 218 // fastcall and stdcall functions usually need @42 at the end to specify 219 // the argument info. 220 FunctionType *FT = F->getFunctionType(); 221 if ((CC == CallingConv::X86_FastCall || CC == CallingConv::X86_StdCall) && 222 // "Pure" variadic functions do not receive @0 suffix. 223 (!FT->isVarArg() || FT->getNumParams() == 0 || 224 (FT->getNumParams() == 1 && F->hasStructRetAttr()))) 225 AddFastCallStdCallSuffix(OutName, F, TD); 226 } 227 } 228 } 229 230 /// getSymbol - Return the MCSymbol for the specified global value. This 231 /// symbol is the main label that is the address of the global. 232 MCSymbol *Mangler::getSymbol(const GlobalValue *GV) { 233 SmallString<60> NameStr; 234 getNameWithPrefix(NameStr, GV, false); 235 return Context.GetOrCreateSymbol(NameStr.str()); 236 } 237 238 239