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#include "llvm/Support/ErrorHandling.h"
24#include "llvm/Support/SourceMgr.h"
25#include "llvm/Support/Signals.h"
26using namespace llvm;
27
28typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
29typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
30typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
31
32
33MCContext::MCContext(const MCAsmInfo &mai, const MCRegisterInfo &mri,
34                     const MCObjectFileInfo *mofi, const SourceMgr *mgr) :
35  SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi),
36  Allocator(), Symbols(Allocator), UsedNames(Allocator),
37  NextUniqueID(0),
38  CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
39  AllowTemporaryLabels(true) {
40  MachOUniquingMap = 0;
41  ELFUniquingMap = 0;
42  COFFUniquingMap = 0;
43
44  SecureLogFile = getenv("AS_SECURE_LOG_FILE");
45  SecureLog = 0;
46  SecureLogUsed = false;
47
48  DwarfLocSeen = false;
49  GenDwarfForAssembly = false;
50  GenDwarfFileNumber = 0;
51}
52
53MCContext::~MCContext() {
54  // NOTE: The symbols are all allocated out of a bump pointer allocator,
55  // we don't need to free them here.
56
57  // If we have the MachO uniquing map, free it.
58  delete (MachOUniqueMapTy*)MachOUniquingMap;
59  delete (ELFUniqueMapTy*)ELFUniquingMap;
60  delete (COFFUniqueMapTy*)COFFUniquingMap;
61
62  // If the stream for the .secure_log_unique directive was created free it.
63  delete (raw_ostream*)SecureLog;
64}
65
66//===----------------------------------------------------------------------===//
67// Symbol Manipulation
68//===----------------------------------------------------------------------===//
69
70MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
71  assert(!Name.empty() && "Normal symbols cannot be unnamed!");
72
73  // Do the lookup and get the entire StringMapEntry.  We want access to the
74  // key if we are creating the entry.
75  StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
76  MCSymbol *Sym = Entry.getValue();
77
78  if (Sym)
79    return Sym;
80
81  Sym = CreateSymbol(Name);
82  Entry.setValue(Sym);
83  return Sym;
84}
85
86MCSymbol *MCContext::CreateSymbol(StringRef Name) {
87  // Determine whether this is an assembler temporary or normal label, if used.
88  bool isTemporary = false;
89  if (AllowTemporaryLabels)
90    isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
91
92  StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
93  if (NameEntry->getValue()) {
94    assert(isTemporary && "Cannot rename non temporary symbols");
95    SmallString<128> NewName = Name;
96    do {
97      NewName.resize(Name.size());
98      raw_svector_ostream(NewName) << NextUniqueID++;
99      NameEntry = &UsedNames.GetOrCreateValue(NewName);
100    } while (NameEntry->getValue());
101  }
102  NameEntry->setValue(true);
103
104  // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
105  // to the copy of the string that is embedded in the UsedNames entry.
106  MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
107
108  return Result;
109}
110
111MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
112  SmallString<128> NameSV;
113  Name.toVector(NameSV);
114  return GetOrCreateSymbol(NameSV.str());
115}
116
117MCSymbol *MCContext::CreateTempSymbol() {
118  SmallString<128> NameSV;
119  raw_svector_ostream(NameSV)
120    << MAI.getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
121  return CreateSymbol(NameSV);
122}
123
124unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
125  MCLabel *&Label = Instances[LocalLabelVal];
126  if (!Label)
127    Label = new (*this) MCLabel(0);
128  return Label->incInstance();
129}
130
131unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
132  MCLabel *&Label = Instances[LocalLabelVal];
133  if (!Label)
134    Label = new (*this) MCLabel(0);
135  return Label->getInstance();
136}
137
138MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
139  return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
140                           Twine(LocalLabelVal) +
141                           "\2" +
142                           Twine(NextInstance(LocalLabelVal)));
143}
144MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
145                                               int bORf) {
146  return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
147                           Twine(LocalLabelVal) +
148                           "\2" +
149                           Twine(GetInstance(LocalLabelVal) + bORf));
150}
151
152MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
153  return Symbols.lookup(Name);
154}
155
156MCSymbol *MCContext::LookupSymbol(const Twine &Name) const {
157  SmallString<128> NameSV;
158  Name.toVector(NameSV);
159  return LookupSymbol(NameSV.str());
160}
161
162//===----------------------------------------------------------------------===//
163// Section Management
164//===----------------------------------------------------------------------===//
165
166const MCSectionMachO *MCContext::
167getMachOSection(StringRef Segment, StringRef Section,
168                unsigned TypeAndAttributes,
169                unsigned Reserved2, SectionKind Kind) {
170
171  // We unique sections by their segment/section pair.  The returned section
172  // may not have the same flags as the requested section, if so this should be
173  // diagnosed by the client as an error.
174
175  // Create the map if it doesn't already exist.
176  if (MachOUniquingMap == 0)
177    MachOUniquingMap = new MachOUniqueMapTy();
178  MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
179
180  // Form the name to look up.
181  SmallString<64> Name;
182  Name += Segment;
183  Name.push_back(',');
184  Name += Section;
185
186  // Do the lookup, if we have a hit, return it.
187  const MCSectionMachO *&Entry = Map[Name.str()];
188  if (Entry) return Entry;
189
190  // Otherwise, return a new section.
191  return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
192                                            Reserved2, Kind);
193}
194
195const MCSectionELF *MCContext::
196getELFSection(StringRef Section, unsigned Type, unsigned Flags,
197              SectionKind Kind) {
198  return getELFSection(Section, Type, Flags, Kind, 0, "");
199}
200
201const MCSectionELF *MCContext::
202getELFSection(StringRef Section, unsigned Type, unsigned Flags,
203              SectionKind Kind, unsigned EntrySize, StringRef Group) {
204  if (ELFUniquingMap == 0)
205    ELFUniquingMap = new ELFUniqueMapTy();
206  ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
207
208  // Do the lookup, if we have a hit, return it.
209  StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
210  if (Entry.getValue()) return Entry.getValue();
211
212  // Possibly refine the entry size first.
213  if (!EntrySize) {
214    EntrySize = MCSectionELF::DetermineEntrySize(Kind);
215  }
216
217  MCSymbol *GroupSym = NULL;
218  if (!Group.empty())
219    GroupSym = GetOrCreateSymbol(Group);
220
221  MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags,
222                                                  Kind, EntrySize, GroupSym);
223  Entry.setValue(Result);
224  return Result;
225}
226
227const MCSectionELF *MCContext::CreateELFGroupSection() {
228  MCSectionELF *Result =
229    new (*this) MCSectionELF(".group", ELF::SHT_GROUP, 0,
230                             SectionKind::getReadOnly(), 4, NULL);
231  return Result;
232}
233
234const MCSection *MCContext::getCOFFSection(StringRef Section,
235                                           unsigned Characteristics,
236                                           int Selection,
237                                           SectionKind Kind) {
238  if (COFFUniquingMap == 0)
239    COFFUniquingMap = new COFFUniqueMapTy();
240  COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
241
242  // Do the lookup, if we have a hit, return it.
243  StringMapEntry<const MCSectionCOFF*> &Entry = Map.GetOrCreateValue(Section);
244  if (Entry.getValue()) return Entry.getValue();
245
246  MCSectionCOFF *Result = new (*this) MCSectionCOFF(Entry.getKey(),
247                                                    Characteristics,
248                                                    Selection, Kind);
249
250  Entry.setValue(Result);
251  return Result;
252}
253
254//===----------------------------------------------------------------------===//
255// Dwarf Management
256//===----------------------------------------------------------------------===//
257
258/// GetDwarfFile - takes a file name an number to place in the dwarf file and
259/// directory tables.  If the file number has already been allocated it is an
260/// error and zero is returned and the client reports the error, else the
261/// allocated file number is returned.  The file numbers may be in any order.
262unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
263                                 unsigned FileNumber) {
264  // TODO: a FileNumber of zero says to use the next available file number.
265  // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
266  // to not be less than one.  This needs to be change to be not less than zero.
267
268  // Make space for this FileNumber in the MCDwarfFiles vector if needed.
269  if (FileNumber >= MCDwarfFiles.size()) {
270    MCDwarfFiles.resize(FileNumber + 1);
271  } else {
272    MCDwarfFile *&ExistingFile = MCDwarfFiles[FileNumber];
273    if (ExistingFile)
274      // It is an error to use see the same number more than once.
275      return 0;
276  }
277
278  // Get the new MCDwarfFile slot for this FileNumber.
279  MCDwarfFile *&File = MCDwarfFiles[FileNumber];
280
281  if (Directory.empty()) {
282    // Separate the directory part from the basename of the FileName.
283    StringRef tFileName = sys::path::filename(FileName);
284    if (!tFileName.empty()) {
285      Directory = sys::path::parent_path(FileName);
286      if (!Directory.empty())
287        FileName = tFileName;
288    }
289  }
290
291  // Find or make a entry in the MCDwarfDirs vector for this Directory.
292  // Capture directory name.
293  unsigned DirIndex;
294  if (Directory.empty()) {
295    // For FileNames with no directories a DirIndex of 0 is used.
296    DirIndex = 0;
297  } else {
298    DirIndex = 0;
299    for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
300      if (Directory == MCDwarfDirs[DirIndex])
301        break;
302    }
303    if (DirIndex >= MCDwarfDirs.size()) {
304      char *Buf = static_cast<char *>(Allocate(Directory.size()));
305      memcpy(Buf, Directory.data(), Directory.size());
306      MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
307    }
308    // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
309    // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
310    // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
311    // are stored at MCDwarfFiles[FileNumber].Name .
312    DirIndex++;
313  }
314
315  // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
316  // vector.
317  char *Buf = static_cast<char *>(Allocate(FileName.size()));
318  memcpy(Buf, FileName.data(), FileName.size());
319  File = new (*this) MCDwarfFile(StringRef(Buf, FileName.size()), DirIndex);
320
321  // return the allocated FileNumber.
322  return FileNumber;
323}
324
325/// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
326/// currently is assigned and false otherwise.
327bool MCContext::isValidDwarfFileNumber(unsigned FileNumber) {
328  if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
329    return false;
330
331  return MCDwarfFiles[FileNumber] != 0;
332}
333
334void MCContext::FatalError(SMLoc Loc, const Twine &Msg) {
335  // If we have a source manager and a location, use it. Otherwise just
336  // use the generic report_fatal_error().
337  if (!SrcMgr || Loc == SMLoc())
338    report_fatal_error(Msg);
339
340  // Use the source manager to print the message.
341  SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
342
343  // If we reached here, we are failing ungracefully. Run the interrupt handlers
344  // to make sure any special cleanups get done, in particular that we remove
345  // files registered with RemoveFileOnSignal.
346  sys::RunInterruptHandlers();
347  exit(1);
348}
349