MCContext.cpp revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338 
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#include <map>
29
30using namespace llvm;
31
32typedef std::pair<std::string, std::string> SectionGroupPair;
33
34typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
35typedef std::map<SectionGroupPair, const MCSectionELF *> ELFUniqueMapTy;
36typedef std::map<SectionGroupPair, const MCSectionCOFF *> COFFUniqueMapTy;
37
38MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
39                     const MCObjectFileInfo *mofi, const SourceMgr *mgr,
40                     bool DoAutoReset)
41    : SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi), Allocator(),
42      Symbols(Allocator), UsedNames(Allocator), NextUniqueID(0),
43      CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0), DwarfLocSeen(false),
44      GenDwarfForAssembly(false), GenDwarfFileNumber(0),
45      AllowTemporaryLabels(true), DwarfCompileUnitID(0),
46      AutoReset(DoAutoReset) {
47
48  error_code EC = llvm::sys::fs::current_path(CompilationDir);
49  if (EC)
50    CompilationDir.clear();
51
52  MachOUniquingMap = 0;
53  ELFUniquingMap = 0;
54  COFFUniquingMap = 0;
55
56  SecureLogFile = getenv("AS_SECURE_LOG_FILE");
57  SecureLog = 0;
58  SecureLogUsed = false;
59
60  if (SrcMgr && SrcMgr->getNumBuffers() > 0)
61    MainFileName = SrcMgr->getMemoryBuffer(0)->getBufferIdentifier();
62}
63
64MCContext::~MCContext() {
65
66  if (AutoReset)
67    reset();
68
69  // NOTE: The symbols are all allocated out of a bump pointer allocator,
70  // we don't need to free them here.
71
72  // If the stream for the .secure_log_unique directive was created free it.
73  delete (raw_ostream*)SecureLog;
74}
75
76//===----------------------------------------------------------------------===//
77// Module Lifetime Management
78//===----------------------------------------------------------------------===//
79
80void MCContext::reset() {
81  UsedNames.clear();
82  Symbols.clear();
83  Allocator.Reset();
84  Instances.clear();
85  MCDwarfLineTablesCUMap.clear();
86  MCGenDwarfLabelEntries.clear();
87  DwarfDebugFlags = StringRef();
88  DwarfCompileUnitID = 0;
89  CurrentDwarfLoc = MCDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0);
90
91  // If we have the MachO uniquing map, free it.
92  delete (MachOUniqueMapTy*)MachOUniquingMap;
93  delete (ELFUniqueMapTy*)ELFUniquingMap;
94  delete (COFFUniqueMapTy*)COFFUniquingMap;
95  MachOUniquingMap = 0;
96  ELFUniquingMap = 0;
97  COFFUniquingMap = 0;
98
99  NextUniqueID = 0;
100  AllowTemporaryLabels = true;
101  DwarfLocSeen = false;
102  GenDwarfForAssembly = false;
103  GenDwarfFileNumber = 0;
104}
105
106//===----------------------------------------------------------------------===//
107// Symbol Manipulation
108//===----------------------------------------------------------------------===//
109
110MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
111  assert(!Name.empty() && "Normal symbols cannot be unnamed!");
112
113  // Do the lookup and get the entire StringMapEntry.  We want access to the
114  // key if we are creating the entry.
115  StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
116  MCSymbol *Sym = Entry.getValue();
117
118  if (Sym)
119    return Sym;
120
121  Sym = CreateSymbol(Name);
122  Entry.setValue(Sym);
123  return Sym;
124}
125
126MCSymbol *MCContext::CreateSymbol(StringRef Name) {
127  // Determine whether this is an assembler temporary or normal label, if used.
128  bool isTemporary = false;
129  if (AllowTemporaryLabels)
130    isTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
131
132  StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
133  if (NameEntry->getValue()) {
134    assert(isTemporary && "Cannot rename non-temporary symbols");
135    SmallString<128> NewName = Name;
136    do {
137      NewName.resize(Name.size());
138      raw_svector_ostream(NewName) << NextUniqueID++;
139      NameEntry = &UsedNames.GetOrCreateValue(NewName);
140    } while (NameEntry->getValue());
141  }
142  NameEntry->setValue(true);
143
144  // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
145  // to the copy of the string that is embedded in the UsedNames entry.
146  MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
147
148  return Result;
149}
150
151MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
152  SmallString<128> NameSV;
153  return GetOrCreateSymbol(Name.toStringRef(NameSV));
154}
155
156MCSymbol *MCContext::CreateLinkerPrivateTempSymbol() {
157  SmallString<128> NameSV;
158  raw_svector_ostream(NameSV)
159    << MAI->getLinkerPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
160  return CreateSymbol(NameSV);
161}
162
163MCSymbol *MCContext::CreateTempSymbol() {
164  SmallString<128> NameSV;
165  raw_svector_ostream(NameSV)
166    << MAI->getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
167  return CreateSymbol(NameSV);
168}
169
170unsigned MCContext::NextInstance(unsigned LocalLabelVal) {
171  MCLabel *&Label = Instances[LocalLabelVal];
172  if (!Label)
173    Label = new (*this) MCLabel(0);
174  return Label->incInstance();
175}
176
177unsigned MCContext::GetInstance(unsigned LocalLabelVal) {
178  MCLabel *&Label = Instances[LocalLabelVal];
179  if (!Label)
180    Label = new (*this) MCLabel(0);
181  return Label->getInstance();
182}
183
184MCSymbol *MCContext::getOrCreateDirectionalLocalSymbol(unsigned LocalLabelVal,
185                                                       unsigned Instance) {
186  MCSymbol *&Sym = LocalSymbols[std::make_pair(LocalLabelVal, Instance)];
187  if (!Sym)
188    Sym = CreateTempSymbol();
189  return Sym;
190}
191
192MCSymbol *MCContext::CreateDirectionalLocalSymbol(unsigned LocalLabelVal) {
193  unsigned Instance = NextInstance(LocalLabelVal);
194  return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
195}
196
197MCSymbol *MCContext::GetDirectionalLocalSymbol(unsigned LocalLabelVal,
198                                               bool Before) {
199  unsigned Instance = GetInstance(LocalLabelVal);
200  if (!Before)
201    ++Instance;
202  return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
203}
204
205MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
206  return Symbols.lookup(Name);
207}
208
209MCSymbol *MCContext::LookupSymbol(const Twine &Name) const {
210  SmallString<128> NameSV;
211  Name.toVector(NameSV);
212  return LookupSymbol(NameSV.str());
213}
214
215//===----------------------------------------------------------------------===//
216// Section Management
217//===----------------------------------------------------------------------===//
218
219const MCSectionMachO *MCContext::
220getMachOSection(StringRef Segment, StringRef Section,
221                unsigned TypeAndAttributes,
222                unsigned Reserved2, SectionKind Kind) {
223
224  // We unique sections by their segment/section pair.  The returned section
225  // may not have the same flags as the requested section, if so this should be
226  // diagnosed by the client as an error.
227
228  // Create the map if it doesn't already exist.
229  if (MachOUniquingMap == 0)
230    MachOUniquingMap = new MachOUniqueMapTy();
231  MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
232
233  // Form the name to look up.
234  SmallString<64> Name;
235  Name += Segment;
236  Name.push_back(',');
237  Name += Section;
238
239  // Do the lookup, if we have a hit, return it.
240  const MCSectionMachO *&Entry = Map[Name.str()];
241  if (Entry) return Entry;
242
243  // Otherwise, return a new section.
244  return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
245                                            Reserved2, Kind);
246}
247
248const MCSectionELF *MCContext::
249getELFSection(StringRef Section, unsigned Type, unsigned Flags,
250              SectionKind Kind) {
251  return getELFSection(Section, Type, Flags, Kind, 0, "");
252}
253
254const MCSectionELF *MCContext::
255getELFSection(StringRef Section, unsigned Type, unsigned Flags,
256              SectionKind Kind, unsigned EntrySize, StringRef Group) {
257  if (ELFUniquingMap == 0)
258    ELFUniquingMap = new ELFUniqueMapTy();
259  ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
260
261  SmallString<32> ZDebugName;
262  if (MAI->compressDebugSections() && Section.startswith(".debug_") &&
263      Section != ".debug_frame" && Section != ".debug_line")
264    Section = (".z" + Section.drop_front(1)).toStringRef(ZDebugName);
265
266  // Do the lookup, if we have a hit, return it.
267  std::pair<ELFUniqueMapTy::iterator, bool> Entry = Map.insert(
268      std::make_pair(SectionGroupPair(Section, Group), (MCSectionELF *)0));
269  if (!Entry.second) return Entry.first->second;
270
271  // Possibly refine the entry size first.
272  if (!EntrySize) {
273    EntrySize = MCSectionELF::DetermineEntrySize(Kind);
274  }
275
276  MCSymbol *GroupSym = NULL;
277  if (!Group.empty())
278    GroupSym = GetOrCreateSymbol(Group);
279
280  MCSectionELF *Result = new (*this) MCSectionELF(
281      Entry.first->first.first, Type, Flags, Kind, EntrySize, GroupSym);
282  Entry.first->second = Result;
283  return Result;
284}
285
286const MCSectionELF *MCContext::CreateELFGroupSection() {
287  MCSectionELF *Result =
288    new (*this) MCSectionELF(".group", ELF::SHT_GROUP, 0,
289                             SectionKind::getReadOnly(), 4, NULL);
290  return Result;
291}
292
293const MCSectionCOFF *
294MCContext::getCOFFSection(StringRef Section, unsigned Characteristics,
295                          SectionKind Kind, StringRef COMDATSymName,
296                          int Selection, const MCSectionCOFF *Assoc) {
297  if (COFFUniquingMap == 0)
298    COFFUniquingMap = new COFFUniqueMapTy();
299  COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
300
301  // Do the lookup, if we have a hit, return it.
302
303  SectionGroupPair P(Section, COMDATSymName);
304  std::pair<COFFUniqueMapTy::iterator, bool> Entry =
305      Map.insert(std::make_pair(P, (MCSectionCOFF *)0));
306  COFFUniqueMapTy::iterator Iter = Entry.first;
307  if (!Entry.second)
308    return Iter->second;
309
310  const MCSymbol *COMDATSymbol = NULL;
311  if (!COMDATSymName.empty())
312    COMDATSymbol = GetOrCreateSymbol(COMDATSymName);
313
314  MCSectionCOFF *Result =
315      new (*this) MCSectionCOFF(Iter->first.first, Characteristics,
316                                COMDATSymbol, Selection, Assoc, Kind);
317
318  Iter->second = Result;
319  return Result;
320}
321
322const MCSectionCOFF *
323MCContext::getCOFFSection(StringRef Section, unsigned Characteristics,
324                          SectionKind Kind) {
325  return getCOFFSection(Section, Characteristics, Kind, "", 0);
326}
327
328const MCSectionCOFF *MCContext::getCOFFSection(StringRef Section) {
329  if (COFFUniquingMap == 0)
330    COFFUniquingMap = new COFFUniqueMapTy();
331  COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
332
333  SectionGroupPair P(Section, "");
334  COFFUniqueMapTy::iterator Iter = Map.find(P);
335  if (Iter == Map.end())
336    return 0;
337  return Iter->second;
338}
339
340//===----------------------------------------------------------------------===//
341// Dwarf Management
342//===----------------------------------------------------------------------===//
343
344/// GetDwarfFile - takes a file name an number to place in the dwarf file and
345/// directory tables.  If the file number has already been allocated it is an
346/// error and zero is returned and the client reports the error, else the
347/// allocated file number is returned.  The file numbers may be in any order.
348unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
349                                 unsigned FileNumber, unsigned CUID) {
350  MCDwarfLineTable &Table = MCDwarfLineTablesCUMap[CUID];
351  return Table.getFile(Directory, FileName, FileNumber);
352}
353
354/// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
355/// currently is assigned and false otherwise.
356bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
357  const SmallVectorImpl<MCDwarfFile>& MCDwarfFiles = getMCDwarfFiles(CUID);
358  if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
359    return false;
360
361  return !MCDwarfFiles[FileNumber].Name.empty();
362}
363
364void MCContext::FatalError(SMLoc Loc, const Twine &Msg) {
365  // If we have a source manager and a location, use it. Otherwise just
366  // use the generic report_fatal_error().
367  if (!SrcMgr || Loc == SMLoc())
368    report_fatal_error(Msg, false);
369
370  // Use the source manager to print the message.
371  SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
372
373  // If we reached here, we are failing ungracefully. Run the interrupt handlers
374  // to make sure any special cleanups get done, in particular that we remove
375  // files registered with RemoveFileOnSignal.
376  sys::RunInterruptHandlers();
377  exit(1);
378}
379