Mangler.cpp revision 206083 
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"
23using namespace llvm;
24
25static bool isAcceptableChar(char C) {
26  if ((C < 'a' || C > 'z') &&
27      (C < 'A' || C > 'Z') &&
28      (C < '0' || C > '9') &&
29      C != '_' && C != '$' && C != '.' && C != '@')
30    return false;
31  return true;
32}
33
34static char HexDigit(int V) {
35  return V < 10 ? V+'0' : V+'A'-10;
36}
37
38static void MangleLetter(SmallVectorImpl<char> &OutName, unsigned char C) {
39  OutName.push_back('_');
40  OutName.push_back(HexDigit(C >> 4));
41  OutName.push_back(HexDigit(C & 15));
42  OutName.push_back('_');
43}
44
45/// NameNeedsEscaping - Return true if the identifier \arg Str needs quotes
46/// for this assembler.
47static bool NameNeedsEscaping(StringRef Str, const MCAsmInfo &MAI) {
48  assert(!Str.empty() && "Cannot create an empty MCSymbol");
49
50  // If the first character is a number and the target does not allow this, we
51  // need quotes.
52  if (!MAI.doesAllowNameToStartWithDigit() && Str[0] >= '0' && Str[0] <= '9')
53    return true;
54
55  // If any of the characters in the string is an unacceptable character, force
56  // quotes.
57  for (unsigned i = 0, e = Str.size(); i != e; ++i)
58    if (!isAcceptableChar(Str[i]))
59      return true;
60  return false;
61}
62
63/// appendMangledName - Add the specified string in mangled form if it uses
64/// any unusual characters.
65static void appendMangledName(SmallVectorImpl<char> &OutName, StringRef Str,
66                              const MCAsmInfo &MAI) {
67  // The first character is not allowed to be a number unless the target
68  // explicitly allows it.
69  if (!MAI.doesAllowNameToStartWithDigit() && Str[0] >= '0' && Str[0] <= '9') {
70    MangleLetter(OutName, Str[0]);
71    Str = Str.substr(1);
72  }
73
74  for (unsigned i = 0, e = Str.size(); i != e; ++i) {
75    if (!isAcceptableChar(Str[i]))
76      MangleLetter(OutName, Str[i]);
77    else
78      OutName.push_back(Str[i]);
79  }
80}
81
82
83/// appendMangledQuotedName - On systems that support quoted symbols, we still
84/// have to escape some (obscure) characters like " and \n which would break the
85/// assembler's lexing.
86static void appendMangledQuotedName(SmallVectorImpl<char> &OutName,
87                                   StringRef Str) {
88  for (unsigned i = 0, e = Str.size(); i != e; ++i) {
89    if (Str[i] == '"' || Str[i] == '\n')
90      MangleLetter(OutName, Str[i]);
91    else
92      OutName.push_back(Str[i]);
93  }
94}
95
96
97/// getNameWithPrefix - Fill OutName with the name of the appropriate prefix
98/// and the specified name as the global variable name.  GVName must not be
99/// empty.
100void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
101                                const Twine &GVName, ManglerPrefixTy PrefixTy) {
102  SmallString<256> TmpData;
103  StringRef Name = GVName.toStringRef(TmpData);
104  assert(!Name.empty() && "getNameWithPrefix requires non-empty name");
105
106  const MCAsmInfo &MAI = Context.getAsmInfo();
107
108  // If the global name is not led with \1, add the appropriate prefixes.
109  if (Name[0] == '\1') {
110    Name = Name.substr(1);
111  } else {
112    if (PrefixTy == Mangler::Private) {
113      const char *Prefix = MAI.getPrivateGlobalPrefix();
114      OutName.append(Prefix, Prefix+strlen(Prefix));
115    } else if (PrefixTy == Mangler::LinkerPrivate) {
116      const char *Prefix = MAI.getLinkerPrivateGlobalPrefix();
117      OutName.append(Prefix, Prefix+strlen(Prefix));
118    }
119
120    const char *Prefix = MAI.getGlobalPrefix();
121    if (Prefix[0] == 0)
122      ; // Common noop, no prefix.
123    else if (Prefix[1] == 0)
124      OutName.push_back(Prefix[0]);  // Common, one character prefix.
125    else
126      OutName.append(Prefix, Prefix+strlen(Prefix)); // Arbitrary length prefix.
127  }
128
129  // If this is a simple string that doesn't need escaping, just append it.
130  if (!NameNeedsEscaping(Name, MAI) ||
131      // If quotes are supported, they can be used unless the string contains
132      // a quote or newline.
133      (MAI.doesAllowQuotesInName() &&
134       Name.find_first_of("\n\"") == StringRef::npos)) {
135    OutName.append(Name.begin(), Name.end());
136    return;
137  }
138
139  // On systems that do not allow quoted names, we need to mangle most
140  // strange characters.
141  if (!MAI.doesAllowQuotesInName())
142    return appendMangledName(OutName, Name, MAI);
143
144  // Okay, the system allows quoted strings.  We can quote most anything, the
145  // only characters that need escaping are " and \n.
146  assert(Name.find_first_of("\n\"") != StringRef::npos);
147  return appendMangledQuotedName(OutName, Name);
148}
149
150/// AddFastCallStdCallSuffix - Microsoft fastcall and stdcall functions require
151/// a suffix on their name indicating the number of words of arguments they
152/// take.
153static void AddFastCallStdCallSuffix(SmallVectorImpl<char> &OutName,
154                                     const Function *F, const TargetData &TD) {
155  // Calculate arguments size total.
156  unsigned ArgWords = 0;
157  for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
158       AI != AE; ++AI) {
159    const Type *Ty = AI->getType();
160    // 'Dereference' type in case of byval parameter attribute
161    if (AI->hasByValAttr())
162      Ty = cast<PointerType>(Ty)->getElementType();
163    // Size should be aligned to DWORD boundary
164    ArgWords += ((TD.getTypeAllocSize(Ty) + 3)/4)*4;
165  }
166
167  raw_svector_ostream(OutName) << '@' << ArgWords;
168}
169
170
171/// getNameWithPrefix - Fill OutName with the name of the appropriate prefix
172/// and the specified global variable's name.  If the global variable doesn't
173/// have a name, this fills in a unique name for the global.
174void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
175                                const GlobalValue *GV,
176                                bool isImplicitlyPrivate) {
177  ManglerPrefixTy PrefixTy = Mangler::Default;
178  if (GV->hasPrivateLinkage() || isImplicitlyPrivate)
179    PrefixTy = Mangler::Private;
180  else if (GV->hasLinkerPrivateLinkage())
181    PrefixTy = Mangler::LinkerPrivate;
182
183  // If this global has a name, handle it simply.
184  if (GV->hasName()) {
185    getNameWithPrefix(OutName, GV->getName(), PrefixTy);
186  } else {
187    // Get the ID for the global, assigning a new one if we haven't got one
188    // already.
189    unsigned &ID = AnonGlobalIDs[GV];
190    if (ID == 0) ID = NextAnonGlobalID++;
191
192    // Must mangle the global into a unique ID.
193    getNameWithPrefix(OutName, "__unnamed_" + Twine(ID), PrefixTy);
194  }
195
196  // If we are supposed to add a microsoft-style suffix for stdcall/fastcall,
197  // add it.
198  if (Context.getAsmInfo().hasMicrosoftFastStdCallMangling()) {
199    if (const Function *F = dyn_cast<Function>(GV)) {
200      CallingConv::ID CC = F->getCallingConv();
201
202      // fastcall functions need to start with @.
203      // FIXME: This logic seems unlikely to be right.
204      if (CC == CallingConv::X86_FastCall) {
205        if (OutName[0] == '_')
206          OutName[0] = '@';
207        else
208          OutName.insert(OutName.begin(), '@');
209      }
210
211      // fastcall and stdcall functions usually need @42 at the end to specify
212      // the argument info.
213      const FunctionType *FT = F->getFunctionType();
214      if ((CC == CallingConv::X86_FastCall || CC == CallingConv::X86_StdCall) &&
215          // "Pure" variadic functions do not receive @0 suffix.
216          (!FT->isVarArg() || FT->getNumParams() == 0 ||
217           (FT->getNumParams() == 1 && F->hasStructRetAttr())))
218        AddFastCallStdCallSuffix(OutName, F, TD);
219    }
220  }
221}
222
223/// getNameWithPrefix - Fill OutName with the name of the appropriate prefix
224/// and the specified global variable's name.  If the global variable doesn't
225/// have a name, this fills in a unique name for the global.
226std::string Mangler::getNameWithPrefix(const GlobalValue *GV,
227                                       bool isImplicitlyPrivate) {
228  SmallString<64> Buf;
229  getNameWithPrefix(Buf, GV, isImplicitlyPrivate);
230  return std::string(Buf.begin(), Buf.end());
231}
232
233/// getSymbol - Return the MCSymbol for the specified global value.  This
234/// symbol is the main label that is the address of the global.
235MCSymbol *Mangler::getSymbol(const GlobalValue *GV) {
236  SmallString<60> NameStr;
237  getNameWithPrefix(NameStr, GV, false);
238  return Context.GetOrCreateSymbol(NameStr.str());
239}
240
241
242