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 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 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 } 234 235 236
