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1 //===- lib/MC/MCContext.cpp - Machine Code Context ------------------------===//
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 #include "llvm/MC/MCContext.h"
11 #include "llvm/MC/MCAsmInfo.h"
12 #include "llvm/MC/MCObjectFileInfo.h"
13 #include "llvm/MC/MCRegisterInfo.h"
14 #include "llvm/MC/MCSectionMachO.h"
15 #include "llvm/MC/MCSectionELF.h"
16 #include "llvm/MC/MCSectionCOFF.h"
17 #include "llvm/MC/MCSymbol.h"
18 #include "llvm/MC/MCLabel.h"
19 #include "llvm/MC/MCDwarf.h"
20 #include "llvm/ADT/SmallString.h"
21 #include "llvm/ADT/Twine.h"
22 #include "llvm/Support/ELF.h"
23 using namespace llvm;
24 
25 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
26 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
27 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
28 
29 
MCContext(const MCAsmInfo & mai,const MCRegisterInfo & mri,const MCObjectFileInfo * mofi)30 MCContext::MCContext(const MCAsmInfo &mai, const MCRegisterInfo &mri,
31                      const MCObjectFileInfo *mofi) :
32   MAI(mai), MRI(mri), MOFI(mofi),
33   Allocator(), Symbols(Allocator), UsedNames(Allocator),
34   NextUniqueID(0),
35   CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
36   AllowTemporaryLabels(true) {
37   MachOUniquingMap = 0;
38   ELFUniquingMap = 0;
39   COFFUniquingMap = 0;
40 
41   SecureLogFile = getenv("AS_SECURE_LOG_FILE");
42   SecureLog = 0;
43   SecureLogUsed = false;
44 
45   DwarfLocSeen = false;
46 }
47 
~MCContext()48 MCContext::~MCContext() {
49   // NOTE: The symbols are all allocated out of a bump pointer allocator,
50   // we don't need to free them here.
51 
52   // If we have the MachO uniquing map, free it.
53   delete (MachOUniqueMapTy*)MachOUniquingMap;
54   delete (ELFUniqueMapTy*)ELFUniquingMap;
55   delete (COFFUniqueMapTy*)COFFUniquingMap;
56 
57   // If the stream for the .secure_log_unique directive was created free it.
58   delete (raw_ostream*)SecureLog;
59 }
60 
61 //===----------------------------------------------------------------------===//
62 // Symbol Manipulation
63 //===----------------------------------------------------------------------===//
64 
GetOrCreateSymbol(StringRef Name)65 MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
66   assert(!Name.empty() && "Normal symbols cannot be unnamed!");
67 
68   // Do the lookup and get the entire StringMapEntry.  We want access to the
69   // key if we are creating the entry.
70   StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
71   MCSymbol *Sym = Entry.getValue();
72 
73   if (Sym)
74     return Sym;
75 
76   Sym = CreateSymbol(Name);
77   Entry.setValue(Sym);
78   return Sym;
79 }
80 
CreateSymbol(StringRef Name)81 MCSymbol *MCContext::CreateSymbol(StringRef Name) {
82   // Determine whether this is an assembler temporary or normal label, if used.
83   bool isTemporary = false;
84   if (AllowTemporaryLabels)
85     isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
86 
87   StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
88   if (NameEntry->getValue()) {
89     assert(isTemporary && "Cannot rename non temporary symbols");
90     SmallString<128> NewName = Name;
91     do {
92       NewName.resize(Name.size());
93       raw_svector_ostream(NewName) << NextUniqueID++;
94       NameEntry = &UsedNames.GetOrCreateValue(NewName);
95     } while (NameEntry->getValue());
96   }
97   NameEntry->setValue(true);
98 
99   // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
100   // to the copy of the string that is embedded in the UsedNames entry.
101   MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
102 
103   return Result;
104 }
105 
GetOrCreateSymbol(const Twine & Name)106 MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
107   SmallString<128> NameSV;
108   Name.toVector(NameSV);
109   return GetOrCreateSymbol(NameSV.str());
110 }
111 
CreateTempSymbol()112 MCSymbol *MCContext::CreateTempSymbol() {
113   SmallString<128> NameSV;
114   raw_svector_ostream(NameSV)
115     << MAI.getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
116   return CreateSymbol(NameSV);
117 }
118 
NextInstance(int64_t LocalLabelVal)119 unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
120   MCLabel *&Label = Instances[LocalLabelVal];
121   if (!Label)
122     Label = new (*this) MCLabel(0);
123   return Label->incInstance();
124 }
125 
GetInstance(int64_t LocalLabelVal)126 unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
127   MCLabel *&Label = Instances[LocalLabelVal];
128   if (!Label)
129     Label = new (*this) MCLabel(0);
130   return Label->getInstance();
131 }
132 
CreateDirectionalLocalSymbol(int64_t LocalLabelVal)133 MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
134   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
135                            Twine(LocalLabelVal) +
136                            "\2" +
137                            Twine(NextInstance(LocalLabelVal)));
138 }
GetDirectionalLocalSymbol(int64_t LocalLabelVal,int bORf)139 MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
140                                                int bORf) {
141   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
142                            Twine(LocalLabelVal) +
143                            "\2" +
144                            Twine(GetInstance(LocalLabelVal) + bORf));
145 }
146 
LookupSymbol(StringRef Name) const147 MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
148   return Symbols.lookup(Name);
149 }
150 
151 //===----------------------------------------------------------------------===//
152 // Section Management
153 //===----------------------------------------------------------------------===//
154 
155 const MCSectionMachO *MCContext::
getMachOSection(StringRef Segment,StringRef Section,unsigned TypeAndAttributes,unsigned Reserved2,SectionKind Kind)156 getMachOSection(StringRef Segment, StringRef Section,
157                 unsigned TypeAndAttributes,
158                 unsigned Reserved2, SectionKind Kind) {
159 
160   // We unique sections by their segment/section pair.  The returned section
161   // may not have the same flags as the requested section, if so this should be
162   // diagnosed by the client as an error.
163 
164   // Create the map if it doesn't already exist.
165   if (MachOUniquingMap == 0)
166     MachOUniquingMap = new MachOUniqueMapTy();
167   MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
168 
169   // Form the name to look up.
170   SmallString<64> Name;
171   Name += Segment;
172   Name.push_back(',');
173   Name += Section;
174 
175   // Do the lookup, if we have a hit, return it.
176   const MCSectionMachO *&Entry = Map[Name.str()];
177   if (Entry) return Entry;
178 
179   // Otherwise, return a new section.
180   return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
181                                             Reserved2, Kind);
182 }
183 
184 const MCSectionELF *MCContext::
getELFSection(StringRef Section,unsigned Type,unsigned Flags,SectionKind Kind)185 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
186               SectionKind Kind) {
187   return getELFSection(Section, Type, Flags, Kind, 0, "");
188 }
189 
190 const MCSectionELF *MCContext::
getELFSection(StringRef Section,unsigned Type,unsigned Flags,SectionKind Kind,unsigned EntrySize,StringRef Group)191 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
192               SectionKind Kind, unsigned EntrySize, StringRef Group) {
193   if (ELFUniquingMap == 0)
194     ELFUniquingMap = new ELFUniqueMapTy();
195   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
196 
197   // Do the lookup, if we have a hit, return it.
198   StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
199   if (Entry.getValue()) return Entry.getValue();
200 
201   // Possibly refine the entry size first.
202   if (!EntrySize) {
203     EntrySize = MCSectionELF::DetermineEntrySize(Kind);
204   }
205 
206   MCSymbol *GroupSym = NULL;
207   if (!Group.empty())
208     GroupSym = GetOrCreateSymbol(Group);
209 
210   MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags,
211                                                   Kind, EntrySize, GroupSym);
212   Entry.setValue(Result);
213   return Result;
214 }
215 
CreateELFGroupSection()216 const MCSectionELF *MCContext::CreateELFGroupSection() {
217   MCSectionELF *Result =
218     new (*this) MCSectionELF(".group", ELF::SHT_GROUP, 0,
219                              SectionKind::getReadOnly(), 4, NULL);
220   return Result;
221 }
222 
getCOFFSection(StringRef Section,unsigned Characteristics,int Selection,SectionKind Kind)223 const MCSection *MCContext::getCOFFSection(StringRef Section,
224                                            unsigned Characteristics,
225                                            int Selection,
226                                            SectionKind Kind) {
227   if (COFFUniquingMap == 0)
228     COFFUniquingMap = new COFFUniqueMapTy();
229   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
230 
231   // Do the lookup, if we have a hit, return it.
232   StringMapEntry<const MCSectionCOFF*> &Entry = Map.GetOrCreateValue(Section);
233   if (Entry.getValue()) return Entry.getValue();
234 
235   MCSectionCOFF *Result = new (*this) MCSectionCOFF(Entry.getKey(),
236                                                     Characteristics,
237                                                     Selection, Kind);
238 
239   Entry.setValue(Result);
240   return Result;
241 }
242 
243 //===----------------------------------------------------------------------===//
244 // Dwarf Management
245 //===----------------------------------------------------------------------===//
246 
247 /// GetDwarfFile - takes a file name an number to place in the dwarf file and
248 /// directory tables.  If the file number has already been allocated it is an
249 /// error and zero is returned and the client reports the error, else the
250 /// allocated file number is returned.  The file numbers may be in any order.
GetDwarfFile(StringRef FileName,unsigned FileNumber)251 unsigned MCContext::GetDwarfFile(StringRef FileName, unsigned FileNumber) {
252   // TODO: a FileNumber of zero says to use the next available file number.
253   // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
254   // to not be less than one.  This needs to be change to be not less than zero.
255 
256   // Make space for this FileNumber in the MCDwarfFiles vector if needed.
257   if (FileNumber >= MCDwarfFiles.size()) {
258     MCDwarfFiles.resize(FileNumber + 1);
259   } else {
260     MCDwarfFile *&ExistingFile = MCDwarfFiles[FileNumber];
261     if (ExistingFile)
262       // It is an error to use see the same number more than once.
263       return 0;
264   }
265 
266   // Get the new MCDwarfFile slot for this FileNumber.
267   MCDwarfFile *&File = MCDwarfFiles[FileNumber];
268 
269   // Separate the directory part from the basename of the FileName.
270   std::pair<StringRef, StringRef> Slash = FileName.rsplit('/');
271 
272   // Find or make a entry in the MCDwarfDirs vector for this Directory.
273   StringRef Name;
274   unsigned DirIndex;
275   // Capture directory name.
276   if (Slash.second.empty()) {
277     Name = Slash.first;
278     DirIndex = 0; // For FileNames with no directories a DirIndex of 0 is used.
279   } else {
280     StringRef Directory = Slash.first;
281     Name = Slash.second;
282     DirIndex = 0;
283     for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
284       if (Directory == MCDwarfDirs[DirIndex])
285         break;
286     }
287     if (DirIndex >= MCDwarfDirs.size()) {
288       char *Buf = static_cast<char *>(Allocate(Directory.size()));
289       memcpy(Buf, Directory.data(), Directory.size());
290       MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
291     }
292     // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
293     // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
294     // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames are
295     // stored at MCDwarfFiles[FileNumber].Name .
296     DirIndex++;
297   }
298 
299   // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
300   // vector.
301   char *Buf = static_cast<char *>(Allocate(Name.size()));
302   memcpy(Buf, Name.data(), Name.size());
303   File = new (*this) MCDwarfFile(StringRef(Buf, Name.size()), DirIndex);
304 
305   // return the allocated FileNumber.
306   return FileNumber;
307 }
308 
309 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
310 /// currently is assigned and false otherwise.
isValidDwarfFileNumber(unsigned FileNumber)311 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber) {
312   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
313     return false;
314 
315   return MCDwarfFiles[FileNumber] != 0;
316 }
317