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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/ADT/SmallString.h"
12 #include "llvm/ADT/Twine.h"
13 #include "llvm/MC/MCAsmInfo.h"
14 #include "llvm/MC/MCDwarf.h"
15 #include "llvm/MC/MCLabel.h"
16 #include "llvm/MC/MCObjectFileInfo.h"
17 #include "llvm/MC/MCRegisterInfo.h"
18 #include "llvm/MC/MCSectionCOFF.h"
19 #include "llvm/MC/MCSectionELF.h"
20 #include "llvm/MC/MCSectionMachO.h"
21 #include "llvm/MC/MCSymbol.h"
22 #include "llvm/Support/ELF.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/FileSystem.h"
25 #include "llvm/Support/MemoryBuffer.h"
26 #include "llvm/Support/Signals.h"
27 #include "llvm/Support/SourceMgr.h"
28 using namespace llvm;
29 
30 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
31 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
32 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
33 
34 
MCContext(const MCAsmInfo * mai,const MCRegisterInfo * mri,const MCObjectFileInfo * mofi,const SourceMgr * mgr,bool DoAutoReset)35 MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
36                      const MCObjectFileInfo *mofi, const SourceMgr *mgr,
37                      bool DoAutoReset) :
38   SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi),
39   Allocator(), Symbols(Allocator), UsedNames(Allocator),
40   NextUniqueID(0),
41   CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
42   DwarfLocSeen(false), GenDwarfForAssembly(false), GenDwarfFileNumber(0),
43   AllowTemporaryLabels(true), DwarfCompileUnitID(0), AutoReset(DoAutoReset) {
44 
45   error_code EC = llvm::sys::fs::current_path(CompilationDir);
46   assert(!EC && "Could not determine the current directory");
47   (void)EC;
48 
49   MachOUniquingMap = 0;
50   ELFUniquingMap = 0;
51   COFFUniquingMap = 0;
52 
53   SecureLogFile = getenv("AS_SECURE_LOG_FILE");
54   SecureLog = 0;
55   SecureLogUsed = false;
56 
57   if (SrcMgr && SrcMgr->getNumBuffers() > 0)
58     MainFileName = SrcMgr->getMemoryBuffer(0)->getBufferIdentifier();
59   else
60     MainFileName = "";
61 }
62 
~MCContext()63 MCContext::~MCContext() {
64 
65   if (AutoReset)
66     reset();
67 
68   // NOTE: The symbols are all allocated out of a bump pointer allocator,
69   // we don't need to free them here.
70 
71   // If the stream for the .secure_log_unique directive was created free it.
72   delete (raw_ostream*)SecureLog;
73 }
74 
75 //===----------------------------------------------------------------------===//
76 // Module Lifetime Management
77 //===----------------------------------------------------------------------===//
78 
reset()79 void MCContext::reset() {
80   UsedNames.clear();
81   Symbols.clear();
82   Allocator.Reset();
83   Instances.clear();
84   MCDwarfFilesCUMap.clear();
85   MCDwarfDirsCUMap.clear();
86   MCGenDwarfLabelEntries.clear();
87   DwarfDebugFlags = StringRef();
88   MCLineSections.clear();
89   MCLineSectionOrder.clear();
90   DwarfCompileUnitID = 0;
91   MCLineTableSymbols.clear();
92   CurrentDwarfLoc = MCDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0);
93 
94   // If we have the MachO uniquing map, free it.
95   delete (MachOUniqueMapTy*)MachOUniquingMap;
96   delete (ELFUniqueMapTy*)ELFUniquingMap;
97   delete (COFFUniqueMapTy*)COFFUniquingMap;
98   MachOUniquingMap = 0;
99   ELFUniquingMap = 0;
100   COFFUniquingMap = 0;
101 
102   NextUniqueID = 0;
103   AllowTemporaryLabels = true;
104   DwarfLocSeen = false;
105   GenDwarfForAssembly = false;
106   GenDwarfFileNumber = 0;
107 }
108 
109 //===----------------------------------------------------------------------===//
110 // Symbol Manipulation
111 //===----------------------------------------------------------------------===//
112 
GetOrCreateSymbol(StringRef Name)113 MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
114   assert(!Name.empty() && "Normal symbols cannot be unnamed!");
115 
116   // Do the lookup and get the entire StringMapEntry.  We want access to the
117   // key if we are creating the entry.
118   StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
119   MCSymbol *Sym = Entry.getValue();
120 
121   if (Sym)
122     return Sym;
123 
124   Sym = CreateSymbol(Name);
125   Entry.setValue(Sym);
126   return Sym;
127 }
128 
CreateSymbol(StringRef Name)129 MCSymbol *MCContext::CreateSymbol(StringRef Name) {
130   // Determine whether this is an assembler temporary or normal label, if used.
131   bool isTemporary = false;
132   if (AllowTemporaryLabels)
133     isTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
134 
135   StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
136   if (NameEntry->getValue()) {
137     assert(isTemporary && "Cannot rename non temporary symbols");
138     SmallString<128> NewName = Name;
139     do {
140       NewName.resize(Name.size());
141       raw_svector_ostream(NewName) << NextUniqueID++;
142       NameEntry = &UsedNames.GetOrCreateValue(NewName);
143     } while (NameEntry->getValue());
144   }
145   NameEntry->setValue(true);
146 
147   // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
148   // to the copy of the string that is embedded in the UsedNames entry.
149   MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
150 
151   return Result;
152 }
153 
GetOrCreateSymbol(const Twine & Name)154 MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
155   SmallString<128> NameSV;
156   Name.toVector(NameSV);
157   return GetOrCreateSymbol(NameSV.str());
158 }
159 
CreateTempSymbol()160 MCSymbol *MCContext::CreateTempSymbol() {
161   SmallString<128> NameSV;
162   raw_svector_ostream(NameSV)
163     << MAI->getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
164   return CreateSymbol(NameSV);
165 }
166 
NextInstance(int64_t LocalLabelVal)167 unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
168   MCLabel *&Label = Instances[LocalLabelVal];
169   if (!Label)
170     Label = new (*this) MCLabel(0);
171   return Label->incInstance();
172 }
173 
GetInstance(int64_t LocalLabelVal)174 unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
175   MCLabel *&Label = Instances[LocalLabelVal];
176   if (!Label)
177     Label = new (*this) MCLabel(0);
178   return Label->getInstance();
179 }
180 
CreateDirectionalLocalSymbol(int64_t LocalLabelVal)181 MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
182   return GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) +
183                            Twine(LocalLabelVal) +
184                            "\2" +
185                            Twine(NextInstance(LocalLabelVal)));
186 }
GetDirectionalLocalSymbol(int64_t LocalLabelVal,int bORf)187 MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
188                                                int bORf) {
189   return GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) +
190                            Twine(LocalLabelVal) +
191                            "\2" +
192                            Twine(GetInstance(LocalLabelVal) + bORf));
193 }
194 
LookupSymbol(StringRef Name) const195 MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
196   return Symbols.lookup(Name);
197 }
198 
LookupSymbol(const Twine & Name) const199 MCSymbol *MCContext::LookupSymbol(const Twine &Name) const {
200   SmallString<128> NameSV;
201   Name.toVector(NameSV);
202   return LookupSymbol(NameSV.str());
203 }
204 
205 //===----------------------------------------------------------------------===//
206 // Section Management
207 //===----------------------------------------------------------------------===//
208 
209 const MCSectionMachO *MCContext::
getMachOSection(StringRef Segment,StringRef Section,unsigned TypeAndAttributes,unsigned Reserved2,SectionKind Kind)210 getMachOSection(StringRef Segment, StringRef Section,
211                 unsigned TypeAndAttributes,
212                 unsigned Reserved2, SectionKind Kind) {
213 
214   // We unique sections by their segment/section pair.  The returned section
215   // may not have the same flags as the requested section, if so this should be
216   // diagnosed by the client as an error.
217 
218   // Create the map if it doesn't already exist.
219   if (MachOUniquingMap == 0)
220     MachOUniquingMap = new MachOUniqueMapTy();
221   MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
222 
223   // Form the name to look up.
224   SmallString<64> Name;
225   Name += Segment;
226   Name.push_back(',');
227   Name += Section;
228 
229   // Do the lookup, if we have a hit, return it.
230   const MCSectionMachO *&Entry = Map[Name.str()];
231   if (Entry) return Entry;
232 
233   // Otherwise, return a new section.
234   return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
235                                             Reserved2, Kind);
236 }
237 
238 const MCSectionELF *MCContext::
getELFSection(StringRef Section,unsigned Type,unsigned Flags,SectionKind Kind)239 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
240               SectionKind Kind) {
241   return getELFSection(Section, Type, Flags, Kind, 0, "");
242 }
243 
244 const MCSectionELF *MCContext::
getELFSection(StringRef Section,unsigned Type,unsigned Flags,SectionKind Kind,unsigned EntrySize,StringRef Group)245 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
246               SectionKind Kind, unsigned EntrySize, StringRef Group) {
247   if (ELFUniquingMap == 0)
248     ELFUniquingMap = new ELFUniqueMapTy();
249   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
250 
251   // Do the lookup, if we have a hit, return it.
252   StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
253   if (Entry.getValue()) return Entry.getValue();
254 
255   // Possibly refine the entry size first.
256   if (!EntrySize) {
257     EntrySize = MCSectionELF::DetermineEntrySize(Kind);
258   }
259 
260   MCSymbol *GroupSym = NULL;
261   if (!Group.empty())
262     GroupSym = GetOrCreateSymbol(Group);
263 
264   MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags,
265                                                   Kind, EntrySize, GroupSym);
266   Entry.setValue(Result);
267   return Result;
268 }
269 
CreateELFGroupSection()270 const MCSectionELF *MCContext::CreateELFGroupSection() {
271   MCSectionELF *Result =
272     new (*this) MCSectionELF(".group", ELF::SHT_GROUP, 0,
273                              SectionKind::getReadOnly(), 4, NULL);
274   return Result;
275 }
276 
getCOFFSection(StringRef Section,unsigned Characteristics,SectionKind Kind,int Selection,const MCSectionCOFF * Assoc)277 const MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
278                                                unsigned Characteristics,
279                                                SectionKind Kind, int Selection,
280                                                const MCSectionCOFF *Assoc) {
281   if (COFFUniquingMap == 0)
282     COFFUniquingMap = new COFFUniqueMapTy();
283   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
284 
285   // Do the lookup, if we have a hit, return it.
286   StringMapEntry<const MCSectionCOFF*> &Entry = Map.GetOrCreateValue(Section);
287   if (Entry.getValue()) return Entry.getValue();
288 
289   MCSectionCOFF *Result = new (*this) MCSectionCOFF(Entry.getKey(),
290                                                     Characteristics,
291                                                     Selection, Assoc, Kind);
292 
293   Entry.setValue(Result);
294   return Result;
295 }
296 
getCOFFSection(StringRef Section)297 const MCSectionCOFF *MCContext::getCOFFSection(StringRef Section) {
298   if (COFFUniquingMap == 0)
299     COFFUniquingMap = new COFFUniqueMapTy();
300   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
301 
302   return Map.lookup(Section);
303 }
304 
305 //===----------------------------------------------------------------------===//
306 // Dwarf Management
307 //===----------------------------------------------------------------------===//
308 
309 /// GetDwarfFile - takes a file name an number to place in the dwarf file and
310 /// directory tables.  If the file number has already been allocated it is an
311 /// error and zero is returned and the client reports the error, else the
312 /// allocated file number is returned.  The file numbers may be in any order.
GetDwarfFile(StringRef Directory,StringRef FileName,unsigned FileNumber,unsigned CUID)313 unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
314                                  unsigned FileNumber, unsigned CUID) {
315   // TODO: a FileNumber of zero says to use the next available file number.
316   // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
317   // to not be less than one.  This needs to be change to be not less than zero.
318 
319   SmallVectorImpl<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
320   SmallVectorImpl<StringRef>& MCDwarfDirs = MCDwarfDirsCUMap[CUID];
321   // Make space for this FileNumber in the MCDwarfFiles vector if needed.
322   if (FileNumber >= MCDwarfFiles.size()) {
323     MCDwarfFiles.resize(FileNumber + 1);
324   } else {
325     MCDwarfFile *&ExistingFile = MCDwarfFiles[FileNumber];
326     if (ExistingFile)
327       // It is an error to use see the same number more than once.
328       return 0;
329   }
330 
331   // Get the new MCDwarfFile slot for this FileNumber.
332   MCDwarfFile *&File = MCDwarfFiles[FileNumber];
333 
334   if (Directory.empty()) {
335     // Separate the directory part from the basename of the FileName.
336     StringRef tFileName = sys::path::filename(FileName);
337     if (!tFileName.empty()) {
338       Directory = sys::path::parent_path(FileName);
339       if (!Directory.empty())
340         FileName = tFileName;
341     }
342   }
343 
344   // Find or make a entry in the MCDwarfDirs vector for this Directory.
345   // Capture directory name.
346   unsigned DirIndex;
347   if (Directory.empty()) {
348     // For FileNames with no directories a DirIndex of 0 is used.
349     DirIndex = 0;
350   } else {
351     DirIndex = 0;
352     for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
353       if (Directory == MCDwarfDirs[DirIndex])
354         break;
355     }
356     if (DirIndex >= MCDwarfDirs.size()) {
357       char *Buf = static_cast<char *>(Allocate(Directory.size()));
358       memcpy(Buf, Directory.data(), Directory.size());
359       MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
360     }
361     // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
362     // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
363     // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
364     // are stored at MCDwarfFiles[FileNumber].Name .
365     DirIndex++;
366   }
367 
368   // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
369   // vector.
370   char *Buf = static_cast<char *>(Allocate(FileName.size()));
371   memcpy(Buf, FileName.data(), FileName.size());
372   File = new (*this) MCDwarfFile(StringRef(Buf, FileName.size()), DirIndex);
373 
374   // return the allocated FileNumber.
375   return FileNumber;
376 }
377 
378 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
379 /// currently is assigned and false otherwise.
isValidDwarfFileNumber(unsigned FileNumber,unsigned CUID)380 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
381   SmallVectorImpl<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
382   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
383     return false;
384 
385   return MCDwarfFiles[FileNumber] != 0;
386 }
387 
FatalError(SMLoc Loc,const Twine & Msg)388 void MCContext::FatalError(SMLoc Loc, const Twine &Msg) {
389   // If we have a source manager and a location, use it. Otherwise just
390   // use the generic report_fatal_error().
391   if (!SrcMgr || Loc == SMLoc())
392     report_fatal_error(Msg);
393 
394   // Use the source manager to print the message.
395   SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
396 
397   // If we reached here, we are failing ungracefully. Run the interrupt handlers
398   // to make sure any special cleanups get done, in particular that we remove
399   // files registered with RemoveFileOnSignal.
400   sys::RunInterruptHandlers();
401   exit(1);
402 }
403