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 
29 #include <map>
30 
31 using namespace llvm;
32 
33 typedef std::pair<std::string, std::string> SectionGroupPair;
34 
35 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
36 typedef std::map<SectionGroupPair, const MCSectionELF *> ELFUniqueMapTy;
37 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
38 
39 
40 MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
41                      const MCObjectFileInfo *mofi, const SourceMgr *mgr,
42                      bool DoAutoReset) :
43   SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi),
44   Allocator(), Symbols(Allocator), UsedNames(Allocator),
45   NextUniqueID(0),
46   CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
47   DwarfLocSeen(false), GenDwarfForAssembly(false), GenDwarfFileNumber(0),
48   AllowTemporaryLabels(true), DwarfCompileUnitID(0), AutoReset(DoAutoReset) {
49 
50   error_code EC = llvm::sys::fs::current_path(CompilationDir);
51   assert(!EC && "Could not determine the current directory");
52   (void)EC;
53 
54   MachOUniquingMap = 0;
55   ELFUniquingMap = 0;
56   COFFUniquingMap = 0;
57 
58   SecureLogFile = getenv("AS_SECURE_LOG_FILE");
59   SecureLog = 0;
60   SecureLogUsed = false;
61 
62   if (SrcMgr && SrcMgr->getNumBuffers() > 0)
63     MainFileName = SrcMgr->getMemoryBuffer(0)->getBufferIdentifier();
64   else
65     MainFileName = "";
66 }
67 
68 MCContext::~MCContext() {
69 
70   if (AutoReset)
71     reset();
72 
73   // NOTE: The symbols are all allocated out of a bump pointer allocator,
74   // we don't need to free them here.
75 
76   // If the stream for the .secure_log_unique directive was created free it.
77   delete (raw_ostream*)SecureLog;
78 }
79 
80 //===----------------------------------------------------------------------===//
81 // Module Lifetime Management
82 //===----------------------------------------------------------------------===//
83 
84 void MCContext::reset() {
85   UsedNames.clear();
86   Symbols.clear();
87   Allocator.Reset();
88   Instances.clear();
89   MCDwarfFilesCUMap.clear();
90   MCDwarfDirsCUMap.clear();
91   MCGenDwarfLabelEntries.clear();
92   DwarfDebugFlags = StringRef();
93   MCLineSections.clear();
94   MCLineSectionOrder.clear();
95   DwarfCompileUnitID = 0;
96   MCLineTableSymbols.clear();
97   CurrentDwarfLoc = MCDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0);
98 
99   // If we have the MachO uniquing map, free it.
100   delete (MachOUniqueMapTy*)MachOUniquingMap;
101   delete (ELFUniqueMapTy*)ELFUniquingMap;
102   delete (COFFUniqueMapTy*)COFFUniquingMap;
103   MachOUniquingMap = 0;
104   ELFUniquingMap = 0;
105   COFFUniquingMap = 0;
106 
107   NextUniqueID = 0;
108   AllowTemporaryLabels = true;
109   DwarfLocSeen = false;
110   GenDwarfForAssembly = false;
111   GenDwarfFileNumber = 0;
112 }
113 
114 //===----------------------------------------------------------------------===//
115 // Symbol Manipulation
116 //===----------------------------------------------------------------------===//
117 
118 MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
119   assert(!Name.empty() && "Normal symbols cannot be unnamed!");
120 
121   // Do the lookup and get the entire StringMapEntry.  We want access to the
122   // key if we are creating the entry.
123   StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
124   MCSymbol *Sym = Entry.getValue();
125 
126   if (Sym)
127     return Sym;
128 
129   Sym = CreateSymbol(Name);
130   Entry.setValue(Sym);
131   return Sym;
132 }
133 
134 MCSymbol *MCContext::CreateSymbol(StringRef Name) {
135   // Determine whether this is an assembler temporary or normal label, if used.
136   bool isTemporary = false;
137   if (AllowTemporaryLabels)
138     isTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
139 
140   StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
141   if (NameEntry->getValue()) {
142     assert(isTemporary && "Cannot rename non temporary symbols");
143     SmallString<128> NewName = Name;
144     do {
145       NewName.resize(Name.size());
146       raw_svector_ostream(NewName) << NextUniqueID++;
147       NameEntry = &UsedNames.GetOrCreateValue(NewName);
148     } while (NameEntry->getValue());
149   }
150   NameEntry->setValue(true);
151 
152   // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
153   // to the copy of the string that is embedded in the UsedNames entry.
154   MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
155 
156   return Result;
157 }
158 
159 MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
160   SmallString<128> NameSV;
161   Name.toVector(NameSV);
162   return GetOrCreateSymbol(NameSV.str());
163 }
164 
165 MCSymbol *MCContext::CreateTempSymbol() {
166   SmallString<128> NameSV;
167   raw_svector_ostream(NameSV)
168     << MAI->getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
169   return CreateSymbol(NameSV);
170 }
171 
172 unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
173   MCLabel *&Label = Instances[LocalLabelVal];
174   if (!Label)
175     Label = new (*this) MCLabel(0);
176   return Label->incInstance();
177 }
178 
179 unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
180   MCLabel *&Label = Instances[LocalLabelVal];
181   if (!Label)
182     Label = new (*this) MCLabel(0);
183   return Label->getInstance();
184 }
185 
186 MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
187   return GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) +
188                            Twine(LocalLabelVal) +
189                            "\2" +
190                            Twine(NextInstance(LocalLabelVal)));
191 }
192 MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
193                                                int bORf) {
194   return GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) +
195                            Twine(LocalLabelVal) +
196                            "\2" +
197                            Twine(GetInstance(LocalLabelVal) + bORf));
198 }
199 
200 MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
201   return Symbols.lookup(Name);
202 }
203 
204 MCSymbol *MCContext::LookupSymbol(const Twine &Name) const {
205   SmallString<128> NameSV;
206   Name.toVector(NameSV);
207   return LookupSymbol(NameSV.str());
208 }
209 
210 //===----------------------------------------------------------------------===//
211 // Section Management
212 //===----------------------------------------------------------------------===//
213 
214 const MCSectionMachO *MCContext::
215 getMachOSection(StringRef Segment, StringRef Section,
216                 unsigned TypeAndAttributes,
217                 unsigned Reserved2, SectionKind Kind) {
218 
219   // We unique sections by their segment/section pair.  The returned section
220   // may not have the same flags as the requested section, if so this should be
221   // diagnosed by the client as an error.
222 
223   // Create the map if it doesn't already exist.
224   if (MachOUniquingMap == 0)
225     MachOUniquingMap = new MachOUniqueMapTy();
226   MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
227 
228   // Form the name to look up.
229   SmallString<64> Name;
230   Name += Segment;
231   Name.push_back(',');
232   Name += Section;
233 
234   // Do the lookup, if we have a hit, return it.
235   const MCSectionMachO *&Entry = Map[Name.str()];
236   if (Entry) return Entry;
237 
238   // Otherwise, return a new section.
239   return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
240                                             Reserved2, Kind);
241 }
242 
243 const MCSectionELF *MCContext::
244 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
245               SectionKind Kind) {
246   return getELFSection(Section, Type, Flags, Kind, 0, "");
247 }
248 
249 const MCSectionELF *MCContext::
250 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
251               SectionKind Kind, unsigned EntrySize, StringRef Group) {
252   if (ELFUniquingMap == 0)
253     ELFUniquingMap = new ELFUniqueMapTy();
254   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
255 
256   // Do the lookup, if we have a hit, return it.
257   std::pair<ELFUniqueMapTy::iterator, bool> Entry = Map.insert(
258       std::make_pair(SectionGroupPair(Section, Group), (MCSectionELF *)0));
259   if (!Entry.second) return Entry.first->second;
260 
261   // Possibly refine the entry size first.
262   if (!EntrySize) {
263     EntrySize = MCSectionELF::DetermineEntrySize(Kind);
264   }
265 
266   MCSymbol *GroupSym = NULL;
267   if (!Group.empty())
268     GroupSym = GetOrCreateSymbol(Group);
269 
270   MCSectionELF *Result = new (*this) MCSectionELF(
271       Entry.first->first.first, Type, Flags, Kind, EntrySize, GroupSym);
272   Entry.first->second = Result;
273   return Result;
274 }
275 
276 const MCSectionELF *MCContext::CreateELFGroupSection() {
277   MCSectionELF *Result =
278     new (*this) MCSectionELF(".group", ELF::SHT_GROUP, 0,
279                              SectionKind::getReadOnly(), 4, NULL);
280   return Result;
281 }
282 
283 const MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
284                                                unsigned Characteristics,
285                                                SectionKind Kind, int Selection,
286                                                const MCSectionCOFF *Assoc) {
287   if (COFFUniquingMap == 0)
288     COFFUniquingMap = new COFFUniqueMapTy();
289   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
290 
291   // Do the lookup, if we have a hit, return it.
292   StringMapEntry<const MCSectionCOFF*> &Entry = Map.GetOrCreateValue(Section);
293   if (Entry.getValue()) return Entry.getValue();
294 
295   MCSectionCOFF *Result = new (*this) MCSectionCOFF(Entry.getKey(),
296                                                     Characteristics,
297                                                     Selection, Assoc, Kind);
298 
299   Entry.setValue(Result);
300   return Result;
301 }
302 
303 const MCSectionCOFF *MCContext::getCOFFSection(StringRef Section) {
304   if (COFFUniquingMap == 0)
305     COFFUniquingMap = new COFFUniqueMapTy();
306   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
307 
308   return Map.lookup(Section);
309 }
310 
311 //===----------------------------------------------------------------------===//
312 // Dwarf Management
313 //===----------------------------------------------------------------------===//
314 
315 /// GetDwarfFile - takes a file name an number to place in the dwarf file and
316 /// directory tables.  If the file number has already been allocated it is an
317 /// error and zero is returned and the client reports the error, else the
318 /// allocated file number is returned.  The file numbers may be in any order.
319 unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
320                                  unsigned FileNumber, unsigned CUID) {
321   // TODO: a FileNumber of zero says to use the next available file number.
322   // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
323   // to not be less than one.  This needs to be change to be not less than zero.
324 
325   SmallVectorImpl<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
326   SmallVectorImpl<StringRef>& MCDwarfDirs = MCDwarfDirsCUMap[CUID];
327   // Make space for this FileNumber in the MCDwarfFiles vector if needed.
328   if (FileNumber >= MCDwarfFiles.size()) {
329     MCDwarfFiles.resize(FileNumber + 1);
330   } else {
331     MCDwarfFile *&ExistingFile = MCDwarfFiles[FileNumber];
332     if (ExistingFile)
333       // It is an error to use see the same number more than once.
334       return 0;
335   }
336 
337   // Get the new MCDwarfFile slot for this FileNumber.
338   MCDwarfFile *&File = MCDwarfFiles[FileNumber];
339 
340   if (Directory.empty()) {
341     // Separate the directory part from the basename of the FileName.
342     StringRef tFileName = sys::path::filename(FileName);
343     if (!tFileName.empty()) {
344       Directory = sys::path::parent_path(FileName);
345       if (!Directory.empty())
346         FileName = tFileName;
347     }
348   }
349 
350   // Find or make a entry in the MCDwarfDirs vector for this Directory.
351   // Capture directory name.
352   unsigned DirIndex;
353   if (Directory.empty()) {
354     // For FileNames with no directories a DirIndex of 0 is used.
355     DirIndex = 0;
356   } else {
357     DirIndex = 0;
358     for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
359       if (Directory == MCDwarfDirs[DirIndex])
360         break;
361     }
362     if (DirIndex >= MCDwarfDirs.size()) {
363       char *Buf = static_cast<char *>(Allocate(Directory.size()));
364       memcpy(Buf, Directory.data(), Directory.size());
365       MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
366     }
367     // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
368     // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
369     // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
370     // are stored at MCDwarfFiles[FileNumber].Name .
371     DirIndex++;
372   }
373 
374   // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
375   // vector.
376   char *Buf = static_cast<char *>(Allocate(FileName.size()));
377   memcpy(Buf, FileName.data(), FileName.size());
378   File = new (*this) MCDwarfFile(StringRef(Buf, FileName.size()), DirIndex);
379 
380   // return the allocated FileNumber.
381   return FileNumber;
382 }
383 
384 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
385 /// currently is assigned and false otherwise.
386 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
387   SmallVectorImpl<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
388   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
389     return false;
390 
391   return MCDwarfFiles[FileNumber] != 0;
392 }
393 
394 void MCContext::FatalError(SMLoc Loc, const Twine &Msg) {
395   // If we have a source manager and a location, use it. Otherwise just
396   // use the generic report_fatal_error().
397   if (!SrcMgr || Loc == SMLoc())
398     report_fatal_error(Msg);
399 
400   // Use the source manager to print the message.
401   SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
402 
403   // If we reached here, we are failing ungracefully. Run the interrupt handlers
404   // to make sure any special cleanups get done, in particular that we remove
405   // files registered with RemoveFileOnSignal.
406   sys::RunInterruptHandlers();
407   exit(1);
408 }
409