MCContext.cpp revision 9f44724be058d17944dcd9ef6a6b57734b3744b8 
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/MCSectionMachO.h"
13#include "llvm/MC/MCSectionELF.h"
14#include "llvm/MC/MCSectionCOFF.h"
15#include "llvm/MC/MCSymbol.h"
16#include "llvm/MC/MCLabel.h"
17#include "llvm/MC/MCDwarf.h"
18#include "llvm/ADT/SmallString.h"
19#include "llvm/ADT/Twine.h"
20using namespace llvm;
21
22typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
23typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
24typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
25
26
27MCContext::MCContext(const MCAsmInfo &mai) : MAI(mai), NextUniqueID(0),
28                     CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0) {
29  MachOUniquingMap = 0;
30  ELFUniquingMap = 0;
31  COFFUniquingMap = 0;
32
33  SecureLogFile = getenv("AS_SECURE_LOG_FILE");
34  SecureLog = 0;
35  SecureLogUsed = false;
36
37  DwarfLocSeen = false;
38}
39
40MCContext::~MCContext() {
41  // NOTE: The symbols are all allocated out of a bump pointer allocator,
42  // we don't need to free them here.
43
44  // If we have the MachO uniquing map, free it.
45  delete (MachOUniqueMapTy*)MachOUniquingMap;
46  delete (ELFUniqueMapTy*)ELFUniquingMap;
47  delete (COFFUniqueMapTy*)COFFUniquingMap;
48
49  // If the stream for the .secure_log_unique directive was created free it.
50  delete (raw_ostream*)SecureLog;
51}
52
53//===----------------------------------------------------------------------===//
54// Symbol Manipulation
55//===----------------------------------------------------------------------===//
56
57MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
58  assert(!Name.empty() && "Normal symbols cannot be unnamed!");
59
60  // Do the lookup and get the entire StringMapEntry.  We want access to the
61  // key if we are creating the entry.
62  StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
63  MCSymbol *Sym = Entry.getValue();
64
65  if (Sym)
66    return Sym;
67
68  Sym = CreateSymbol(Name);
69  Entry.setValue(Sym);
70  return Sym;
71}
72
73MCSymbol *MCContext::CreateSymbol(StringRef Name) {
74  // Determine whether this is an assembler temporary or normal label.
75  bool isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
76
77  StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
78  if (NameEntry->getValue()) {
79    assert(isTemporary && "Cannot rename non temporary symbols");
80    SmallString<128> NewName;
81    do {
82      Twine T = Name + Twine(NextUniqueID++);
83      T.toVector(NewName);
84      StringRef foo = NewName;
85      NameEntry = &UsedNames.GetOrCreateValue(foo);
86    } while (NameEntry->getValue());
87  }
88  NameEntry->setValue(true);
89
90  // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
91  // to the copy of the string that is embedded in the UsedNames entry.
92  MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
93
94  return Result;
95}
96
97MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
98  SmallString<128> NameSV;
99  Name.toVector(NameSV);
100  return GetOrCreateSymbol(NameSV.str());
101}
102
103MCSymbol *MCContext::CreateTempSymbol() {
104  SmallString<128> NameSV;
105  Twine Name = Twine(MAI.getPrivateGlobalPrefix()) + "tmp" +
106    Twine(NextUniqueID++);
107  Name.toVector(NameSV);
108  return CreateSymbol(NameSV);
109}
110
111unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
112  MCLabel *&Label = Instances[LocalLabelVal];
113  if (!Label)
114    Label = new (*this) MCLabel(0);
115  return Label->incInstance();
116}
117
118unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
119  MCLabel *&Label = Instances[LocalLabelVal];
120  if (!Label)
121    Label = new (*this) MCLabel(0);
122  return Label->getInstance();
123}
124
125MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
126  return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
127                           Twine(LocalLabelVal) +
128                           "\2" +
129                           Twine(NextInstance(LocalLabelVal)));
130}
131MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
132                                               int bORf) {
133  return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
134                           Twine(LocalLabelVal) +
135                           "\2" +
136                           Twine(GetInstance(LocalLabelVal) + bORf));
137}
138
139MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
140  return Symbols.lookup(Name);
141}
142
143//===----------------------------------------------------------------------===//
144// Section Management
145//===----------------------------------------------------------------------===//
146
147const MCSectionMachO *MCContext::
148getMachOSection(StringRef Segment, StringRef Section,
149                unsigned TypeAndAttributes,
150                unsigned Reserved2, SectionKind Kind) {
151
152  // We unique sections by their segment/section pair.  The returned section
153  // may not have the same flags as the requested section, if so this should be
154  // diagnosed by the client as an error.
155
156  // Create the map if it doesn't already exist.
157  if (MachOUniquingMap == 0)
158    MachOUniquingMap = new MachOUniqueMapTy();
159  MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
160
161  // Form the name to look up.
162  SmallString<64> Name;
163  Name += Segment;
164  Name.push_back(',');
165  Name += Section;
166
167  // Do the lookup, if we have a hit, return it.
168  const MCSectionMachO *&Entry = Map[Name.str()];
169  if (Entry) return Entry;
170
171  // Otherwise, return a new section.
172  return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
173                                            Reserved2, Kind);
174}
175
176const MCSectionELF *MCContext::
177getELFSection(StringRef Section, unsigned Type, unsigned Flags,
178              SectionKind Kind) {
179  return getELFSection(Section, Type, Flags, Kind, 0, "");
180}
181
182const MCSectionELF *MCContext::
183getELFSection(StringRef Section, unsigned Type, unsigned Flags,
184              SectionKind Kind, unsigned EntrySize, StringRef Group) {
185  if (ELFUniquingMap == 0)
186    ELFUniquingMap = new ELFUniqueMapTy();
187  ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
188
189  // Do the lookup, if we have a hit, return it.
190  StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
191  if (Entry.getValue()) return Entry.getValue();
192
193  // Possibly refine the entry size first.
194  if (!EntrySize) {
195    EntrySize = MCSectionELF::DetermineEntrySize(Kind);
196  }
197
198  MCSymbol *GroupSym = NULL;
199  if (!Group.empty())
200    GroupSym = GetOrCreateSymbol(Group);
201
202  MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags,
203                                                  Kind, EntrySize, GroupSym);
204  Entry.setValue(Result);
205  return Result;
206}
207
208const MCSectionELF *MCContext::CreateELFGroupSection() {
209  MCSectionELF *Result =
210    new (*this) MCSectionELF(".group", MCSectionELF::SHT_GROUP, 0,
211                             SectionKind::getReadOnly(), 4, NULL);
212  return Result;
213}
214
215const MCSection *MCContext::getCOFFSection(StringRef Section,
216                                           unsigned Characteristics,
217                                           int Selection,
218                                           SectionKind Kind) {
219  if (COFFUniquingMap == 0)
220    COFFUniquingMap = new COFFUniqueMapTy();
221  COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
222
223  // Do the lookup, if we have a hit, return it.
224  StringMapEntry<const MCSectionCOFF*> &Entry = Map.GetOrCreateValue(Section);
225  if (Entry.getValue()) return Entry.getValue();
226
227  MCSectionCOFF *Result = new (*this) MCSectionCOFF(Entry.getKey(),
228                                                    Characteristics,
229                                                    Selection, Kind);
230
231  Entry.setValue(Result);
232  return Result;
233}
234
235//===----------------------------------------------------------------------===//
236// Dwarf Management
237//===----------------------------------------------------------------------===//
238
239/// GetDwarfFile - takes a file name an number to place in the dwarf file and
240/// directory tables.  If the file number has already been allocated it is an
241/// error and zero is returned and the client reports the error, else the
242/// allocated file number is returned.  The file numbers may be in any order.
243unsigned MCContext::GetDwarfFile(StringRef FileName, unsigned FileNumber) {
244  // TODO: a FileNumber of zero says to use the next available file number.
245  // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
246  // to not be less than one.  This needs to be change to be not less than zero.
247
248  // Make space for this FileNumber in the MCDwarfFiles vector if needed.
249  if (FileNumber >= MCDwarfFiles.size()) {
250    MCDwarfFiles.resize(FileNumber + 1);
251  } else {
252    MCDwarfFile *&ExistingFile = MCDwarfFiles[FileNumber];
253    if (ExistingFile)
254      // It is an error to use see the same number more than once.
255      return 0;
256  }
257
258  // Get the new MCDwarfFile slot for this FileNumber.
259  MCDwarfFile *&File = MCDwarfFiles[FileNumber];
260
261  // Separate the directory part from the basename of the FileName.
262  std::pair<StringRef, StringRef> Slash = FileName.rsplit('/');
263
264  // Find or make a entry in the MCDwarfDirs vector for this Directory.
265  StringRef Name;
266  unsigned DirIndex;
267  // Capture directory name.
268  if (Slash.second.empty()) {
269    Name = Slash.first;
270    DirIndex = 0; // For FileNames with no directories a DirIndex of 0 is used.
271  } else {
272    StringRef Directory = Slash.first;
273    Name = Slash.second;
274    for (DirIndex = 0; DirIndex < MCDwarfDirs.size(); DirIndex++) {
275      if (Directory == MCDwarfDirs[DirIndex])
276        break;
277    }
278    if (DirIndex >= MCDwarfDirs.size()) {
279      char *Buf = static_cast<char *>(Allocate(Directory.size()));
280      memcpy(Buf, Directory.data(), Directory.size());
281      MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
282    }
283    // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
284    // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
285    // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames are
286    // stored at MCDwarfFiles[FileNumber].Name .
287    DirIndex++;
288  }
289
290  // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
291  // vector.
292  char *Buf = static_cast<char *>(Allocate(Name.size()));
293  memcpy(Buf, Name.data(), Name.size());
294  File = new (*this) MCDwarfFile(StringRef(Buf, Name.size()), DirIndex);
295
296  // return the allocated FileNumber.
297  return FileNumber;
298}
299
300/// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
301/// currently is assigned and false otherwise.
302bool MCContext::isValidDwarfFileNumber(unsigned FileNumber) {
303  if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
304    return false;
305
306  return MCDwarfFiles[FileNumber] != 0;
307}
308