Mangler.cpp revision 226633 
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, 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
35static char HexDigit(int V) {
36  return V < 10 ? V+'0' : V+'A'-10;
37}
38
39static 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.
48static 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.
67static 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.
89static 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.
103void 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.
156static 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.
177void 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.
229MCSymbol *Mangler::getSymbol(const GlobalValue *GV) {
230  SmallString<60> NameStr;
231  getNameWithPrefix(NameStr, GV, false);
232  return Context.GetOrCreateSymbol(NameStr.str());
233}
234
235
236