1 //===-- Mangler.cpp - Self-contained c/asm llvm name mangler --------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Unified name mangler for assembly backends.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/IR/Mangler.h"
14 #include "llvm/ADT/SmallString.h"
15 #include "llvm/ADT/StringExtras.h"
16 #include "llvm/ADT/Triple.h"
17 #include "llvm/ADT/Twine.h"
18 #include "llvm/IR/DataLayout.h"
19 #include "llvm/IR/DerivedTypes.h"
20 #include "llvm/IR/Function.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/Support/raw_ostream.h"
23 using namespace llvm;
24
25 namespace {
26 enum ManglerPrefixTy {
27 Default, ///< Emit default string before each symbol.
28 Private, ///< Emit "private" prefix before each symbol.
29 LinkerPrivate ///< Emit "linker private" prefix before each symbol.
30 };
31 }
32
getNameWithPrefixImpl(raw_ostream & OS,const Twine & GVName,ManglerPrefixTy PrefixTy,const DataLayout & DL,char Prefix)33 static void getNameWithPrefixImpl(raw_ostream &OS, const Twine &GVName,
34 ManglerPrefixTy PrefixTy,
35 const DataLayout &DL, char Prefix) {
36 SmallString<256> TmpData;
37 StringRef Name = GVName.toStringRef(TmpData);
38 assert(!Name.empty() && "getNameWithPrefix requires non-empty name");
39
40 // No need to do anything special if the global has the special "do not
41 // mangle" flag in the name.
42 if (Name[0] == '\1') {
43 OS << Name.substr(1);
44 return;
45 }
46
47 if (DL.doNotMangleLeadingQuestionMark() && Name[0] == '?')
48 Prefix = '\0';
49
50 if (PrefixTy == Private)
51 OS << DL.getPrivateGlobalPrefix();
52 else if (PrefixTy == LinkerPrivate)
53 OS << DL.getLinkerPrivateGlobalPrefix();
54
55 if (Prefix != '\0')
56 OS << Prefix;
57
58 // If this is a simple string that doesn't need escaping, just append it.
59 OS << Name;
60 }
61
getNameWithPrefixImpl(raw_ostream & OS,const Twine & GVName,const DataLayout & DL,ManglerPrefixTy PrefixTy)62 static void getNameWithPrefixImpl(raw_ostream &OS, const Twine &GVName,
63 const DataLayout &DL,
64 ManglerPrefixTy PrefixTy) {
65 char Prefix = DL.getGlobalPrefix();
66 return getNameWithPrefixImpl(OS, GVName, PrefixTy, DL, Prefix);
67 }
68
getNameWithPrefix(raw_ostream & OS,const Twine & GVName,const DataLayout & DL)69 void Mangler::getNameWithPrefix(raw_ostream &OS, const Twine &GVName,
70 const DataLayout &DL) {
71 return getNameWithPrefixImpl(OS, GVName, DL, Default);
72 }
73
getNameWithPrefix(SmallVectorImpl<char> & OutName,const Twine & GVName,const DataLayout & DL)74 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
75 const Twine &GVName, const DataLayout &DL) {
76 raw_svector_ostream OS(OutName);
77 char Prefix = DL.getGlobalPrefix();
78 return getNameWithPrefixImpl(OS, GVName, Default, DL, Prefix);
79 }
80
hasByteCountSuffix(CallingConv::ID CC)81 static bool hasByteCountSuffix(CallingConv::ID CC) {
82 switch (CC) {
83 case CallingConv::X86_FastCall:
84 case CallingConv::X86_StdCall:
85 case CallingConv::X86_VectorCall:
86 return true;
87 default:
88 return false;
89 }
90 }
91
92 /// Microsoft fastcall and stdcall functions require a suffix on their name
93 /// indicating the number of words of arguments they take.
addByteCountSuffix(raw_ostream & OS,const Function * F,const DataLayout & DL)94 static void addByteCountSuffix(raw_ostream &OS, const Function *F,
95 const DataLayout &DL) {
96 // Calculate arguments size total.
97 unsigned ArgWords = 0;
98
99 const unsigned PtrSize = DL.getPointerSize();
100
101 for (const Argument &A : F->args()) {
102 // 'Dereference' type in case of byval or inalloca parameter attribute.
103 uint64_t AllocSize = A.hasPassPointeeByValueCopyAttr() ?
104 A.getPassPointeeByValueCopySize(DL) :
105 DL.getTypeAllocSize(A.getType());
106
107 // Size should be aligned to pointer size.
108 ArgWords += alignTo(AllocSize, PtrSize);
109 }
110
111 OS << '@' << ArgWords;
112 }
113
getNameWithPrefix(raw_ostream & OS,const GlobalValue * GV,bool CannotUsePrivateLabel) const114 void Mangler::getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV,
115 bool CannotUsePrivateLabel) const {
116 ManglerPrefixTy PrefixTy = Default;
117 if (GV->hasPrivateLinkage()) {
118 if (CannotUsePrivateLabel)
119 PrefixTy = LinkerPrivate;
120 else
121 PrefixTy = Private;
122 }
123
124 const DataLayout &DL = GV->getParent()->getDataLayout();
125 if (!GV->hasName()) {
126 // Get the ID for the global, assigning a new one if we haven't got one
127 // already.
128 unsigned &ID = AnonGlobalIDs[GV];
129 if (ID == 0)
130 ID = AnonGlobalIDs.size();
131
132 // Must mangle the global into a unique ID.
133 getNameWithPrefixImpl(OS, "__unnamed_" + Twine(ID), DL, PrefixTy);
134 return;
135 }
136
137 StringRef Name = GV->getName();
138 char Prefix = DL.getGlobalPrefix();
139
140 // Mangle functions with Microsoft calling conventions specially. Only do
141 // this mangling for x86_64 vectorcall and 32-bit x86.
142 const Function *MSFunc = dyn_cast<Function>(GV);
143
144 // Don't add byte count suffixes when '\01' or '?' are in the first
145 // character.
146 if (Name.startswith("\01") ||
147 (DL.doNotMangleLeadingQuestionMark() && Name.startswith("?")))
148 MSFunc = nullptr;
149
150 CallingConv::ID CC =
151 MSFunc ? MSFunc->getCallingConv() : (unsigned)CallingConv::C;
152 if (!DL.hasMicrosoftFastStdCallMangling() &&
153 CC != CallingConv::X86_VectorCall)
154 MSFunc = nullptr;
155 if (MSFunc) {
156 if (CC == CallingConv::X86_FastCall)
157 Prefix = '@'; // fastcall functions have an @ prefix instead of _.
158 else if (CC == CallingConv::X86_VectorCall)
159 Prefix = '\0'; // vectorcall functions have no prefix.
160 }
161
162 getNameWithPrefixImpl(OS, Name, PrefixTy, DL, Prefix);
163
164 if (!MSFunc)
165 return;
166
167 // If we are supposed to add a microsoft-style suffix for stdcall, fastcall,
168 // or vectorcall, add it. These functions have a suffix of @N where N is the
169 // cumulative byte size of all of the parameters to the function in decimal.
170 if (CC == CallingConv::X86_VectorCall)
171 OS << '@'; // vectorcall functions use a double @ suffix.
172 FunctionType *FT = MSFunc->getFunctionType();
173 if (hasByteCountSuffix(CC) &&
174 // "Pure" variadic functions do not receive @0 suffix.
175 (!FT->isVarArg() || FT->getNumParams() == 0 ||
176 (FT->getNumParams() == 1 && MSFunc->hasStructRetAttr())))
177 addByteCountSuffix(OS, MSFunc, DL);
178 }
179
getNameWithPrefix(SmallVectorImpl<char> & OutName,const GlobalValue * GV,bool CannotUsePrivateLabel) const180 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
181 const GlobalValue *GV,
182 bool CannotUsePrivateLabel) const {
183 raw_svector_ostream OS(OutName);
184 getNameWithPrefix(OS, GV, CannotUsePrivateLabel);
185 }
186
187 // Check if the name needs quotes to be safe for the linker to interpret.
canBeUnquotedInDirective(char C)188 static bool canBeUnquotedInDirective(char C) {
189 return isAlnum(C) || C == '_' || C == '$' || C == '.' || C == '@';
190 }
191
canBeUnquotedInDirective(StringRef Name)192 static bool canBeUnquotedInDirective(StringRef Name) {
193 if (Name.empty())
194 return false;
195
196 // If any of the characters in the string is an unacceptable character, force
197 // quotes.
198 for (char C : Name) {
199 if (!canBeUnquotedInDirective(C))
200 return false;
201 }
202
203 return true;
204 }
205
emitLinkerFlagsForGlobalCOFF(raw_ostream & OS,const GlobalValue * GV,const Triple & TT,Mangler & Mangler)206 void llvm::emitLinkerFlagsForGlobalCOFF(raw_ostream &OS, const GlobalValue *GV,
207 const Triple &TT, Mangler &Mangler) {
208 if (!GV->hasDLLExportStorageClass() || GV->isDeclaration())
209 return;
210
211 if (TT.isWindowsMSVCEnvironment())
212 OS << " /EXPORT:";
213 else
214 OS << " -export:";
215
216 bool NeedQuotes = GV->hasName() && !canBeUnquotedInDirective(GV->getName());
217 if (NeedQuotes)
218 OS << "\"";
219 if (TT.isWindowsGNUEnvironment() || TT.isWindowsCygwinEnvironment()) {
220 std::string Flag;
221 raw_string_ostream FlagOS(Flag);
222 Mangler.getNameWithPrefix(FlagOS, GV, false);
223 FlagOS.flush();
224 if (Flag[0] == GV->getParent()->getDataLayout().getGlobalPrefix())
225 OS << Flag.substr(1);
226 else
227 OS << Flag;
228 } else {
229 Mangler.getNameWithPrefix(OS, GV, false);
230 }
231 if (NeedQuotes)
232 OS << "\"";
233
234 if (!GV->getValueType()->isFunctionTy()) {
235 if (TT.isWindowsMSVCEnvironment())
236 OS << ",DATA";
237 else
238 OS << ",data";
239 }
240 }
241
emitLinkerFlagsForUsedCOFF(raw_ostream & OS,const GlobalValue * GV,const Triple & T,Mangler & M)242 void llvm::emitLinkerFlagsForUsedCOFF(raw_ostream &OS, const GlobalValue *GV,
243 const Triple &T, Mangler &M) {
244 if (!T.isWindowsMSVCEnvironment())
245 return;
246
247 OS << " /INCLUDE:";
248 bool NeedQuotes = GV->hasName() && !canBeUnquotedInDirective(GV->getName());
249 if (NeedQuotes)
250 OS << "\"";
251 M.getNameWithPrefix(OS, GV, false);
252 if (NeedQuotes)
253 OS << "\"";
254 }
255
256