1 //===-- MCObjectFileInfo.cpp - Object File Information --------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/MC/MCObjectFileInfo.h"
10 #include "llvm/ADT/StringExtras.h"
11 #include "llvm/ADT/Triple.h"
12 #include "llvm/BinaryFormat/COFF.h"
13 #include "llvm/BinaryFormat/ELF.h"
14 #include "llvm/MC/MCAsmInfo.h"
15 #include "llvm/MC/MCContext.h"
16 #include "llvm/MC/MCSection.h"
17 #include "llvm/MC/MCSectionCOFF.h"
18 #include "llvm/MC/MCSectionELF.h"
19 #include "llvm/MC/MCSectionMachO.h"
20 #include "llvm/MC/MCSectionWasm.h"
21 #include "llvm/MC/MCSectionXCOFF.h"
22 
23 using namespace llvm;
24 
25 static bool useCompactUnwind(const Triple &T) {
26   // Only on darwin.
27   if (!T.isOSDarwin())
28     return false;
29 
30   // aarch64 always has it.
31   if (T.getArch() == Triple::aarch64 || T.getArch() == Triple::aarch64_32)
32     return true;
33 
34   // armv7k always has it.
35   if (T.isWatchABI())
36     return true;
37 
38   // Use it on newer version of OS X.
39   if (T.isMacOSX() && !T.isMacOSXVersionLT(10, 6))
40     return true;
41 
42   // And the iOS simulator.
43   if (T.isiOS() &&
44       (T.getArch() == Triple::x86_64 || T.getArch() == Triple::x86))
45     return true;
46 
47   return false;
48 }
49 
50 void MCObjectFileInfo::initMachOMCObjectFileInfo(const Triple &T) {
51   // MachO
52   SupportsWeakOmittedEHFrame = false;
53 
54   EHFrameSection = Ctx->getMachOSection(
55       "__TEXT", "__eh_frame",
56       MachO::S_COALESCED | MachO::S_ATTR_NO_TOC |
57           MachO::S_ATTR_STRIP_STATIC_SYMS | MachO::S_ATTR_LIVE_SUPPORT,
58       SectionKind::getReadOnly());
59 
60   if (T.isOSDarwin() &&
61       (T.getArch() == Triple::aarch64 || T.getArch() == Triple::aarch64_32))
62     SupportsCompactUnwindWithoutEHFrame = true;
63 
64   if (T.isWatchABI())
65     OmitDwarfIfHaveCompactUnwind = true;
66 
67   FDECFIEncoding = dwarf::DW_EH_PE_pcrel;
68 
69   // .comm doesn't support alignment before Leopard.
70   if (T.isMacOSX() && T.isMacOSXVersionLT(10, 5))
71     CommDirectiveSupportsAlignment = false;
72 
73   TextSection // .text
74     = Ctx->getMachOSection("__TEXT", "__text",
75                            MachO::S_ATTR_PURE_INSTRUCTIONS,
76                            SectionKind::getText());
77   DataSection // .data
78       = Ctx->getMachOSection("__DATA", "__data", 0, SectionKind::getData());
79 
80   // BSSSection might not be expected initialized on msvc.
81   BSSSection = nullptr;
82 
83   TLSDataSection // .tdata
84       = Ctx->getMachOSection("__DATA", "__thread_data",
85                              MachO::S_THREAD_LOCAL_REGULAR,
86                              SectionKind::getData());
87   TLSBSSSection // .tbss
88     = Ctx->getMachOSection("__DATA", "__thread_bss",
89                            MachO::S_THREAD_LOCAL_ZEROFILL,
90                            SectionKind::getThreadBSS());
91 
92   // TODO: Verify datarel below.
93   TLSTLVSection // .tlv
94       = Ctx->getMachOSection("__DATA", "__thread_vars",
95                              MachO::S_THREAD_LOCAL_VARIABLES,
96                              SectionKind::getData());
97 
98   TLSThreadInitSection = Ctx->getMachOSection(
99       "__DATA", "__thread_init", MachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
100       SectionKind::getData());
101 
102   CStringSection // .cstring
103     = Ctx->getMachOSection("__TEXT", "__cstring",
104                            MachO::S_CSTRING_LITERALS,
105                            SectionKind::getMergeable1ByteCString());
106   UStringSection
107     = Ctx->getMachOSection("__TEXT","__ustring", 0,
108                            SectionKind::getMergeable2ByteCString());
109   FourByteConstantSection // .literal4
110     = Ctx->getMachOSection("__TEXT", "__literal4",
111                            MachO::S_4BYTE_LITERALS,
112                            SectionKind::getMergeableConst4());
113   EightByteConstantSection // .literal8
114     = Ctx->getMachOSection("__TEXT", "__literal8",
115                            MachO::S_8BYTE_LITERALS,
116                            SectionKind::getMergeableConst8());
117 
118   SixteenByteConstantSection // .literal16
119       = Ctx->getMachOSection("__TEXT", "__literal16",
120                              MachO::S_16BYTE_LITERALS,
121                              SectionKind::getMergeableConst16());
122 
123   ReadOnlySection  // .const
124     = Ctx->getMachOSection("__TEXT", "__const", 0,
125                            SectionKind::getReadOnly());
126 
127   // If the target is not powerpc, map the coal sections to the non-coal
128   // sections.
129   //
130   // "__TEXT/__textcoal_nt" => section "__TEXT/__text"
131   // "__TEXT/__const_coal"  => section "__TEXT/__const"
132   // "__DATA/__datacoal_nt" => section "__DATA/__data"
133   Triple::ArchType ArchTy = T.getArch();
134 
135   ConstDataSection  // .const_data
136     = Ctx->getMachOSection("__DATA", "__const", 0,
137                            SectionKind::getReadOnlyWithRel());
138 
139   if (ArchTy == Triple::ppc || ArchTy == Triple::ppc64) {
140     TextCoalSection
141       = Ctx->getMachOSection("__TEXT", "__textcoal_nt",
142                              MachO::S_COALESCED |
143                              MachO::S_ATTR_PURE_INSTRUCTIONS,
144                              SectionKind::getText());
145     ConstTextCoalSection
146       = Ctx->getMachOSection("__TEXT", "__const_coal",
147                              MachO::S_COALESCED,
148                              SectionKind::getReadOnly());
149     DataCoalSection = Ctx->getMachOSection(
150         "__DATA", "__datacoal_nt", MachO::S_COALESCED, SectionKind::getData());
151     ConstDataCoalSection = DataCoalSection;
152   } else {
153     TextCoalSection = TextSection;
154     ConstTextCoalSection = ReadOnlySection;
155     DataCoalSection = DataSection;
156     ConstDataCoalSection = ConstDataSection;
157   }
158 
159   DataCommonSection
160     = Ctx->getMachOSection("__DATA","__common",
161                            MachO::S_ZEROFILL,
162                            SectionKind::getBSS());
163   DataBSSSection
164     = Ctx->getMachOSection("__DATA","__bss", MachO::S_ZEROFILL,
165                            SectionKind::getBSS());
166 
167 
168   LazySymbolPointerSection
169     = Ctx->getMachOSection("__DATA", "__la_symbol_ptr",
170                            MachO::S_LAZY_SYMBOL_POINTERS,
171                            SectionKind::getMetadata());
172   NonLazySymbolPointerSection
173     = Ctx->getMachOSection("__DATA", "__nl_symbol_ptr",
174                            MachO::S_NON_LAZY_SYMBOL_POINTERS,
175                            SectionKind::getMetadata());
176 
177   ThreadLocalPointerSection
178     = Ctx->getMachOSection("__DATA", "__thread_ptr",
179                            MachO::S_THREAD_LOCAL_VARIABLE_POINTERS,
180                            SectionKind::getMetadata());
181 
182   // Exception Handling.
183   LSDASection = Ctx->getMachOSection("__TEXT", "__gcc_except_tab", 0,
184                                      SectionKind::getReadOnlyWithRel());
185 
186   COFFDebugSymbolsSection = nullptr;
187   COFFDebugTypesSection = nullptr;
188   COFFGlobalTypeHashesSection = nullptr;
189 
190   if (useCompactUnwind(T)) {
191     CompactUnwindSection =
192         Ctx->getMachOSection("__LD", "__compact_unwind", MachO::S_ATTR_DEBUG,
193                              SectionKind::getReadOnly());
194 
195     if (T.getArch() == Triple::x86_64 || T.getArch() == Triple::x86)
196       CompactUnwindDwarfEHFrameOnly = 0x04000000;  // UNWIND_X86_64_MODE_DWARF
197     else if (T.getArch() == Triple::aarch64 || T.getArch() == Triple::aarch64_32)
198       CompactUnwindDwarfEHFrameOnly = 0x03000000;  // UNWIND_ARM64_MODE_DWARF
199     else if (T.getArch() == Triple::arm || T.getArch() == Triple::thumb)
200       CompactUnwindDwarfEHFrameOnly = 0x04000000;  // UNWIND_ARM_MODE_DWARF
201   }
202 
203   // Debug Information.
204   DwarfDebugNamesSection =
205       Ctx->getMachOSection("__DWARF", "__debug_names", MachO::S_ATTR_DEBUG,
206                            SectionKind::getMetadata(), "debug_names_begin");
207   DwarfAccelNamesSection =
208       Ctx->getMachOSection("__DWARF", "__apple_names", MachO::S_ATTR_DEBUG,
209                            SectionKind::getMetadata(), "names_begin");
210   DwarfAccelObjCSection =
211       Ctx->getMachOSection("__DWARF", "__apple_objc", MachO::S_ATTR_DEBUG,
212                            SectionKind::getMetadata(), "objc_begin");
213   // 16 character section limit...
214   DwarfAccelNamespaceSection =
215       Ctx->getMachOSection("__DWARF", "__apple_namespac", MachO::S_ATTR_DEBUG,
216                            SectionKind::getMetadata(), "namespac_begin");
217   DwarfAccelTypesSection =
218       Ctx->getMachOSection("__DWARF", "__apple_types", MachO::S_ATTR_DEBUG,
219                            SectionKind::getMetadata(), "types_begin");
220 
221   DwarfSwiftASTSection =
222       Ctx->getMachOSection("__DWARF", "__swift_ast", MachO::S_ATTR_DEBUG,
223                            SectionKind::getMetadata());
224 
225   DwarfAbbrevSection =
226       Ctx->getMachOSection("__DWARF", "__debug_abbrev", MachO::S_ATTR_DEBUG,
227                            SectionKind::getMetadata(), "section_abbrev");
228   DwarfInfoSection =
229       Ctx->getMachOSection("__DWARF", "__debug_info", MachO::S_ATTR_DEBUG,
230                            SectionKind::getMetadata(), "section_info");
231   DwarfLineSection =
232       Ctx->getMachOSection("__DWARF", "__debug_line", MachO::S_ATTR_DEBUG,
233                            SectionKind::getMetadata(), "section_line");
234   DwarfLineStrSection =
235       Ctx->getMachOSection("__DWARF", "__debug_line_str", MachO::S_ATTR_DEBUG,
236                            SectionKind::getMetadata(), "section_line_str");
237   DwarfFrameSection =
238       Ctx->getMachOSection("__DWARF", "__debug_frame", MachO::S_ATTR_DEBUG,
239                            SectionKind::getMetadata());
240   DwarfPubNamesSection =
241       Ctx->getMachOSection("__DWARF", "__debug_pubnames", MachO::S_ATTR_DEBUG,
242                            SectionKind::getMetadata());
243   DwarfPubTypesSection =
244       Ctx->getMachOSection("__DWARF", "__debug_pubtypes", MachO::S_ATTR_DEBUG,
245                            SectionKind::getMetadata());
246   DwarfGnuPubNamesSection =
247       Ctx->getMachOSection("__DWARF", "__debug_gnu_pubn", MachO::S_ATTR_DEBUG,
248                            SectionKind::getMetadata());
249   DwarfGnuPubTypesSection =
250       Ctx->getMachOSection("__DWARF", "__debug_gnu_pubt", MachO::S_ATTR_DEBUG,
251                            SectionKind::getMetadata());
252   DwarfStrSection =
253       Ctx->getMachOSection("__DWARF", "__debug_str", MachO::S_ATTR_DEBUG,
254                            SectionKind::getMetadata(), "info_string");
255   DwarfStrOffSection =
256       Ctx->getMachOSection("__DWARF", "__debug_str_offs", MachO::S_ATTR_DEBUG,
257                            SectionKind::getMetadata(), "section_str_off");
258   DwarfAddrSection =
259       Ctx->getMachOSection("__DWARF", "__debug_addr", MachO::S_ATTR_DEBUG,
260                            SectionKind::getMetadata(), "section_info");
261   DwarfLocSection =
262       Ctx->getMachOSection("__DWARF", "__debug_loc", MachO::S_ATTR_DEBUG,
263                            SectionKind::getMetadata(), "section_debug_loc");
264   DwarfLoclistsSection =
265       Ctx->getMachOSection("__DWARF", "__debug_loclists", MachO::S_ATTR_DEBUG,
266                            SectionKind::getMetadata(), "section_debug_loc");
267 
268   DwarfARangesSection =
269       Ctx->getMachOSection("__DWARF", "__debug_aranges", MachO::S_ATTR_DEBUG,
270                            SectionKind::getMetadata());
271   DwarfRangesSection =
272       Ctx->getMachOSection("__DWARF", "__debug_ranges", MachO::S_ATTR_DEBUG,
273                            SectionKind::getMetadata(), "debug_range");
274   DwarfRnglistsSection =
275       Ctx->getMachOSection("__DWARF", "__debug_rnglists", MachO::S_ATTR_DEBUG,
276                            SectionKind::getMetadata(), "debug_range");
277   DwarfMacinfoSection =
278       Ctx->getMachOSection("__DWARF", "__debug_macinfo", MachO::S_ATTR_DEBUG,
279                            SectionKind::getMetadata(), "debug_macinfo");
280   DwarfDebugInlineSection =
281       Ctx->getMachOSection("__DWARF", "__debug_inlined", MachO::S_ATTR_DEBUG,
282                            SectionKind::getMetadata());
283   DwarfCUIndexSection =
284       Ctx->getMachOSection("__DWARF", "__debug_cu_index", MachO::S_ATTR_DEBUG,
285                            SectionKind::getMetadata());
286   DwarfTUIndexSection =
287       Ctx->getMachOSection("__DWARF", "__debug_tu_index", MachO::S_ATTR_DEBUG,
288                            SectionKind::getMetadata());
289   StackMapSection = Ctx->getMachOSection("__LLVM_STACKMAPS", "__llvm_stackmaps",
290                                          0, SectionKind::getMetadata());
291 
292   FaultMapSection = Ctx->getMachOSection("__LLVM_FAULTMAPS", "__llvm_faultmaps",
293                                          0, SectionKind::getMetadata());
294 
295   RemarksSection = Ctx->getMachOSection(
296       "__LLVM", "__remarks", MachO::S_ATTR_DEBUG, SectionKind::getMetadata());
297 
298   TLSExtraDataSection = TLSTLVSection;
299 }
300 
301 void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T, bool Large) {
302   switch (T.getArch()) {
303   case Triple::mips:
304   case Triple::mipsel:
305   case Triple::mips64:
306   case Triple::mips64el:
307     FDECFIEncoding = Ctx->getAsmInfo()->getCodePointerSize() == 4
308                          ? dwarf::DW_EH_PE_sdata4
309                          : dwarf::DW_EH_PE_sdata8;
310     break;
311   case Triple::ppc64:
312   case Triple::ppc64le:
313   case Triple::x86_64:
314     FDECFIEncoding = dwarf::DW_EH_PE_pcrel |
315                      (Large ? dwarf::DW_EH_PE_sdata8 : dwarf::DW_EH_PE_sdata4);
316     break;
317   case Triple::bpfel:
318   case Triple::bpfeb:
319     FDECFIEncoding = dwarf::DW_EH_PE_sdata8;
320     break;
321   case Triple::hexagon:
322     FDECFIEncoding =
323         PositionIndependent ? dwarf::DW_EH_PE_pcrel : dwarf::DW_EH_PE_absptr;
324     break;
325   default:
326     FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
327     break;
328   }
329 
330   unsigned EHSectionType = T.getArch() == Triple::x86_64
331                                ? ELF::SHT_X86_64_UNWIND
332                                : ELF::SHT_PROGBITS;
333 
334   // Solaris requires different flags for .eh_frame to seemingly every other
335   // platform.
336   unsigned EHSectionFlags = ELF::SHF_ALLOC;
337   if (T.isOSSolaris() && T.getArch() != Triple::x86_64)
338     EHSectionFlags |= ELF::SHF_WRITE;
339 
340   // ELF
341   BSSSection = Ctx->getELFSection(".bss", ELF::SHT_NOBITS,
342                                   ELF::SHF_WRITE | ELF::SHF_ALLOC);
343 
344   TextSection = Ctx->getELFSection(".text", ELF::SHT_PROGBITS,
345                                    ELF::SHF_EXECINSTR | ELF::SHF_ALLOC);
346 
347   DataSection = Ctx->getELFSection(".data", ELF::SHT_PROGBITS,
348                                    ELF::SHF_WRITE | ELF::SHF_ALLOC);
349 
350   ReadOnlySection =
351       Ctx->getELFSection(".rodata", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
352 
353   TLSDataSection =
354       Ctx->getELFSection(".tdata", ELF::SHT_PROGBITS,
355                          ELF::SHF_ALLOC | ELF::SHF_TLS | ELF::SHF_WRITE);
356 
357   TLSBSSSection = Ctx->getELFSection(
358       ".tbss", ELF::SHT_NOBITS, ELF::SHF_ALLOC | ELF::SHF_TLS | ELF::SHF_WRITE);
359 
360   DataRelROSection = Ctx->getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
361                                         ELF::SHF_ALLOC | ELF::SHF_WRITE);
362 
363   MergeableConst4Section =
364       Ctx->getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
365                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 4, "");
366 
367   MergeableConst8Section =
368       Ctx->getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
369                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 8, "");
370 
371   MergeableConst16Section =
372       Ctx->getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
373                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 16, "");
374 
375   MergeableConst32Section =
376       Ctx->getELFSection(".rodata.cst32", ELF::SHT_PROGBITS,
377                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 32, "");
378 
379   // Exception Handling Sections.
380 
381   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
382   // it contains relocatable pointers.  In PIC mode, this is probably a big
383   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
384   // adjusted or this should be a data section.
385   LSDASection = Ctx->getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
386                                    ELF::SHF_ALLOC);
387 
388   COFFDebugSymbolsSection = nullptr;
389   COFFDebugTypesSection = nullptr;
390 
391   unsigned DebugSecType = ELF::SHT_PROGBITS;
392 
393   // MIPS .debug_* sections should have SHT_MIPS_DWARF section type
394   // to distinguish among sections contain DWARF and ECOFF debug formats.
395   // Sections with ECOFF debug format are obsoleted and marked by SHT_PROGBITS.
396   if (T.isMIPS())
397     DebugSecType = ELF::SHT_MIPS_DWARF;
398 
399   // Debug Info Sections.
400   DwarfAbbrevSection =
401       Ctx->getELFSection(".debug_abbrev", DebugSecType, 0);
402   DwarfInfoSection = Ctx->getELFSection(".debug_info", DebugSecType, 0);
403   DwarfLineSection = Ctx->getELFSection(".debug_line", DebugSecType, 0);
404   DwarfLineStrSection =
405       Ctx->getELFSection(".debug_line_str", DebugSecType,
406                          ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
407   DwarfFrameSection = Ctx->getELFSection(".debug_frame", DebugSecType, 0);
408   DwarfPubNamesSection =
409       Ctx->getELFSection(".debug_pubnames", DebugSecType, 0);
410   DwarfPubTypesSection =
411       Ctx->getELFSection(".debug_pubtypes", DebugSecType, 0);
412   DwarfGnuPubNamesSection =
413       Ctx->getELFSection(".debug_gnu_pubnames", DebugSecType, 0);
414   DwarfGnuPubTypesSection =
415       Ctx->getELFSection(".debug_gnu_pubtypes", DebugSecType, 0);
416   DwarfStrSection =
417       Ctx->getELFSection(".debug_str", DebugSecType,
418                          ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
419   DwarfLocSection = Ctx->getELFSection(".debug_loc", DebugSecType, 0);
420   DwarfARangesSection =
421       Ctx->getELFSection(".debug_aranges", DebugSecType, 0);
422   DwarfRangesSection =
423       Ctx->getELFSection(".debug_ranges", DebugSecType, 0);
424   DwarfMacinfoSection =
425       Ctx->getELFSection(".debug_macinfo", DebugSecType, 0);
426 
427   // DWARF5 Experimental Debug Info
428 
429   // Accelerator Tables
430   DwarfDebugNamesSection =
431       Ctx->getELFSection(".debug_names", ELF::SHT_PROGBITS, 0);
432   DwarfAccelNamesSection =
433       Ctx->getELFSection(".apple_names", ELF::SHT_PROGBITS, 0);
434   DwarfAccelObjCSection =
435       Ctx->getELFSection(".apple_objc", ELF::SHT_PROGBITS, 0);
436   DwarfAccelNamespaceSection =
437       Ctx->getELFSection(".apple_namespaces", ELF::SHT_PROGBITS, 0);
438   DwarfAccelTypesSection =
439       Ctx->getELFSection(".apple_types", ELF::SHT_PROGBITS, 0);
440 
441   // String Offset and Address Sections
442   DwarfStrOffSection =
443       Ctx->getELFSection(".debug_str_offsets", DebugSecType, 0);
444   DwarfAddrSection = Ctx->getELFSection(".debug_addr", DebugSecType, 0);
445   DwarfRnglistsSection = Ctx->getELFSection(".debug_rnglists", DebugSecType, 0);
446   DwarfLoclistsSection = Ctx->getELFSection(".debug_loclists", DebugSecType, 0);
447 
448   // Fission Sections
449   DwarfInfoDWOSection =
450       Ctx->getELFSection(".debug_info.dwo", DebugSecType, ELF::SHF_EXCLUDE);
451   DwarfTypesDWOSection =
452       Ctx->getELFSection(".debug_types.dwo", DebugSecType, ELF::SHF_EXCLUDE);
453   DwarfAbbrevDWOSection =
454       Ctx->getELFSection(".debug_abbrev.dwo", DebugSecType, ELF::SHF_EXCLUDE);
455   DwarfStrDWOSection = Ctx->getELFSection(
456       ".debug_str.dwo", DebugSecType,
457       ELF::SHF_MERGE | ELF::SHF_STRINGS | ELF::SHF_EXCLUDE, 1, "");
458   DwarfLineDWOSection =
459       Ctx->getELFSection(".debug_line.dwo", DebugSecType, ELF::SHF_EXCLUDE);
460   DwarfLocDWOSection =
461       Ctx->getELFSection(".debug_loc.dwo", DebugSecType, ELF::SHF_EXCLUDE);
462   DwarfStrOffDWOSection = Ctx->getELFSection(".debug_str_offsets.dwo",
463                                              DebugSecType, ELF::SHF_EXCLUDE);
464   DwarfRnglistsDWOSection =
465       Ctx->getELFSection(".debug_rnglists.dwo", DebugSecType, ELF::SHF_EXCLUDE);
466   DwarfMacinfoDWOSection =
467       Ctx->getELFSection(".debug_macinfo.dwo", DebugSecType, ELF::SHF_EXCLUDE);
468 
469   DwarfLoclistsDWOSection =
470       Ctx->getELFSection(".debug_loclists.dwo", DebugSecType, ELF::SHF_EXCLUDE);
471 
472   // DWP Sections
473   DwarfCUIndexSection =
474       Ctx->getELFSection(".debug_cu_index", DebugSecType, 0);
475   DwarfTUIndexSection =
476       Ctx->getELFSection(".debug_tu_index", DebugSecType, 0);
477 
478   StackMapSection =
479       Ctx->getELFSection(".llvm_stackmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
480 
481   FaultMapSection =
482       Ctx->getELFSection(".llvm_faultmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
483 
484   EHFrameSection =
485       Ctx->getELFSection(".eh_frame", EHSectionType, EHSectionFlags);
486 
487   StackSizesSection = Ctx->getELFSection(".stack_sizes", ELF::SHT_PROGBITS, 0);
488 }
489 
490 void MCObjectFileInfo::initCOFFMCObjectFileInfo(const Triple &T) {
491   EHFrameSection =
492       Ctx->getCOFFSection(".eh_frame", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
493                                            COFF::IMAGE_SCN_MEM_READ,
494                           SectionKind::getData());
495 
496   // Set the `IMAGE_SCN_MEM_16BIT` flag when compiling for thumb mode.  This is
497   // used to indicate to the linker that the text segment contains thumb instructions
498   // and to set the ISA selection bit for calls accordingly.
499   const bool IsThumb = T.getArch() == Triple::thumb;
500 
501   CommDirectiveSupportsAlignment = true;
502 
503   // COFF
504   BSSSection = Ctx->getCOFFSection(
505       ".bss", COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
506                   COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
507       SectionKind::getBSS());
508   TextSection = Ctx->getCOFFSection(
509       ".text",
510       (IsThumb ? COFF::IMAGE_SCN_MEM_16BIT : (COFF::SectionCharacteristics)0) |
511           COFF::IMAGE_SCN_CNT_CODE | COFF::IMAGE_SCN_MEM_EXECUTE |
512           COFF::IMAGE_SCN_MEM_READ,
513       SectionKind::getText());
514   DataSection = Ctx->getCOFFSection(
515       ".data", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
516                    COFF::IMAGE_SCN_MEM_WRITE,
517       SectionKind::getData());
518   ReadOnlySection = Ctx->getCOFFSection(
519       ".rdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
520       SectionKind::getReadOnly());
521 
522   if (T.getArch() == Triple::x86_64 || T.getArch() == Triple::aarch64) {
523     // On Windows 64 with SEH, the LSDA is emitted into the .xdata section
524     LSDASection = nullptr;
525   } else {
526     LSDASection = Ctx->getCOFFSection(".gcc_except_table",
527                                       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
528                                           COFF::IMAGE_SCN_MEM_READ,
529                                       SectionKind::getReadOnly());
530   }
531 
532   // Debug info.
533   COFFDebugSymbolsSection =
534       Ctx->getCOFFSection(".debug$S", (COFF::IMAGE_SCN_MEM_DISCARDABLE |
535                                        COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
536                                        COFF::IMAGE_SCN_MEM_READ),
537                           SectionKind::getMetadata());
538   COFFDebugTypesSection =
539       Ctx->getCOFFSection(".debug$T", (COFF::IMAGE_SCN_MEM_DISCARDABLE |
540                                        COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
541                                        COFF::IMAGE_SCN_MEM_READ),
542                           SectionKind::getMetadata());
543   COFFGlobalTypeHashesSection = Ctx->getCOFFSection(
544       ".debug$H",
545       (COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
546        COFF::IMAGE_SCN_MEM_READ),
547       SectionKind::getMetadata());
548 
549   DwarfAbbrevSection = Ctx->getCOFFSection(
550       ".debug_abbrev",
551       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
552           COFF::IMAGE_SCN_MEM_READ,
553       SectionKind::getMetadata(), "section_abbrev");
554   DwarfInfoSection = Ctx->getCOFFSection(
555       ".debug_info",
556       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
557           COFF::IMAGE_SCN_MEM_READ,
558       SectionKind::getMetadata(), "section_info");
559   DwarfLineSection = Ctx->getCOFFSection(
560       ".debug_line",
561       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
562           COFF::IMAGE_SCN_MEM_READ,
563       SectionKind::getMetadata(), "section_line");
564   DwarfLineStrSection = Ctx->getCOFFSection(
565       ".debug_line_str",
566       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
567           COFF::IMAGE_SCN_MEM_READ,
568       SectionKind::getMetadata(), "section_line_str");
569   DwarfFrameSection = Ctx->getCOFFSection(
570       ".debug_frame",
571       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
572           COFF::IMAGE_SCN_MEM_READ,
573       SectionKind::getMetadata());
574   DwarfPubNamesSection = Ctx->getCOFFSection(
575       ".debug_pubnames",
576       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
577           COFF::IMAGE_SCN_MEM_READ,
578       SectionKind::getMetadata());
579   DwarfPubTypesSection = Ctx->getCOFFSection(
580       ".debug_pubtypes",
581       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
582           COFF::IMAGE_SCN_MEM_READ,
583       SectionKind::getMetadata());
584   DwarfGnuPubNamesSection = Ctx->getCOFFSection(
585       ".debug_gnu_pubnames",
586       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
587           COFF::IMAGE_SCN_MEM_READ,
588       SectionKind::getMetadata());
589   DwarfGnuPubTypesSection = Ctx->getCOFFSection(
590       ".debug_gnu_pubtypes",
591       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
592           COFF::IMAGE_SCN_MEM_READ,
593       SectionKind::getMetadata());
594   DwarfStrSection = Ctx->getCOFFSection(
595       ".debug_str",
596       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
597           COFF::IMAGE_SCN_MEM_READ,
598       SectionKind::getMetadata(), "info_string");
599   DwarfStrOffSection = Ctx->getCOFFSection(
600       ".debug_str_offsets",
601       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
602           COFF::IMAGE_SCN_MEM_READ,
603       SectionKind::getMetadata(), "section_str_off");
604   DwarfLocSection = Ctx->getCOFFSection(
605       ".debug_loc",
606       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
607           COFF::IMAGE_SCN_MEM_READ,
608       SectionKind::getMetadata(), "section_debug_loc");
609   DwarfARangesSection = Ctx->getCOFFSection(
610       ".debug_aranges",
611       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
612           COFF::IMAGE_SCN_MEM_READ,
613       SectionKind::getMetadata());
614   DwarfRangesSection = Ctx->getCOFFSection(
615       ".debug_ranges",
616       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
617           COFF::IMAGE_SCN_MEM_READ,
618       SectionKind::getMetadata(), "debug_range");
619   DwarfMacinfoSection = Ctx->getCOFFSection(
620       ".debug_macinfo",
621       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
622           COFF::IMAGE_SCN_MEM_READ,
623       SectionKind::getMetadata(), "debug_macinfo");
624   DwarfMacinfoDWOSection = Ctx->getCOFFSection(
625       ".debug_macinfo.dwo",
626       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
627           COFF::IMAGE_SCN_MEM_READ,
628       SectionKind::getMetadata(), "debug_macinfo.dwo");
629   DwarfInfoDWOSection = Ctx->getCOFFSection(
630       ".debug_info.dwo",
631       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
632           COFF::IMAGE_SCN_MEM_READ,
633       SectionKind::getMetadata(), "section_info_dwo");
634   DwarfTypesDWOSection = Ctx->getCOFFSection(
635       ".debug_types.dwo",
636       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
637           COFF::IMAGE_SCN_MEM_READ,
638       SectionKind::getMetadata(), "section_types_dwo");
639   DwarfAbbrevDWOSection = Ctx->getCOFFSection(
640       ".debug_abbrev.dwo",
641       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
642           COFF::IMAGE_SCN_MEM_READ,
643       SectionKind::getMetadata(), "section_abbrev_dwo");
644   DwarfStrDWOSection = Ctx->getCOFFSection(
645       ".debug_str.dwo",
646       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
647           COFF::IMAGE_SCN_MEM_READ,
648       SectionKind::getMetadata(), "skel_string");
649   DwarfLineDWOSection = Ctx->getCOFFSection(
650       ".debug_line.dwo",
651       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
652           COFF::IMAGE_SCN_MEM_READ,
653       SectionKind::getMetadata());
654   DwarfLocDWOSection = Ctx->getCOFFSection(
655       ".debug_loc.dwo",
656       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
657           COFF::IMAGE_SCN_MEM_READ,
658       SectionKind::getMetadata(), "skel_loc");
659   DwarfStrOffDWOSection = Ctx->getCOFFSection(
660       ".debug_str_offsets.dwo",
661       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
662           COFF::IMAGE_SCN_MEM_READ,
663       SectionKind::getMetadata(), "section_str_off_dwo");
664   DwarfAddrSection = Ctx->getCOFFSection(
665       ".debug_addr",
666       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
667           COFF::IMAGE_SCN_MEM_READ,
668       SectionKind::getMetadata(), "addr_sec");
669   DwarfCUIndexSection = Ctx->getCOFFSection(
670       ".debug_cu_index",
671       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
672           COFF::IMAGE_SCN_MEM_READ,
673       SectionKind::getMetadata());
674   DwarfTUIndexSection = Ctx->getCOFFSection(
675       ".debug_tu_index",
676       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
677           COFF::IMAGE_SCN_MEM_READ,
678       SectionKind::getMetadata());
679   DwarfDebugNamesSection = Ctx->getCOFFSection(
680       ".debug_names",
681       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
682           COFF::IMAGE_SCN_MEM_READ,
683       SectionKind::getMetadata(), "debug_names_begin");
684   DwarfAccelNamesSection = Ctx->getCOFFSection(
685       ".apple_names",
686       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
687           COFF::IMAGE_SCN_MEM_READ,
688       SectionKind::getMetadata(), "names_begin");
689   DwarfAccelNamespaceSection = Ctx->getCOFFSection(
690       ".apple_namespaces",
691       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
692           COFF::IMAGE_SCN_MEM_READ,
693       SectionKind::getMetadata(), "namespac_begin");
694   DwarfAccelTypesSection = Ctx->getCOFFSection(
695       ".apple_types",
696       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
697           COFF::IMAGE_SCN_MEM_READ,
698       SectionKind::getMetadata(), "types_begin");
699   DwarfAccelObjCSection = Ctx->getCOFFSection(
700       ".apple_objc",
701       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
702           COFF::IMAGE_SCN_MEM_READ,
703       SectionKind::getMetadata(), "objc_begin");
704 
705   DrectveSection = Ctx->getCOFFSection(
706       ".drectve", COFF::IMAGE_SCN_LNK_INFO | COFF::IMAGE_SCN_LNK_REMOVE,
707       SectionKind::getMetadata());
708 
709   PDataSection = Ctx->getCOFFSection(
710       ".pdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
711       SectionKind::getData());
712 
713   XDataSection = Ctx->getCOFFSection(
714       ".xdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
715       SectionKind::getData());
716 
717   SXDataSection = Ctx->getCOFFSection(".sxdata", COFF::IMAGE_SCN_LNK_INFO,
718                                       SectionKind::getMetadata());
719 
720   GFIDsSection = Ctx->getCOFFSection(".gfids$y",
721                                      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
722                                          COFF::IMAGE_SCN_MEM_READ,
723                                      SectionKind::getMetadata());
724 
725   GLJMPSection = Ctx->getCOFFSection(".gljmp$y",
726                                      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
727                                          COFF::IMAGE_SCN_MEM_READ,
728                                      SectionKind::getMetadata());
729 
730   TLSDataSection = Ctx->getCOFFSection(
731       ".tls$", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
732                    COFF::IMAGE_SCN_MEM_WRITE,
733       SectionKind::getData());
734 
735   StackMapSection = Ctx->getCOFFSection(".llvm_stackmaps",
736                                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
737                                             COFF::IMAGE_SCN_MEM_READ,
738                                         SectionKind::getReadOnly());
739 }
740 
741 void MCObjectFileInfo::initWasmMCObjectFileInfo(const Triple &T) {
742   TextSection = Ctx->getWasmSection(".text", SectionKind::getText());
743   DataSection = Ctx->getWasmSection(".data", SectionKind::getData());
744 
745   DwarfLineSection =
746       Ctx->getWasmSection(".debug_line", SectionKind::getMetadata());
747   DwarfLineStrSection =
748       Ctx->getWasmSection(".debug_line_str", SectionKind::getMetadata());
749   DwarfStrSection =
750       Ctx->getWasmSection(".debug_str", SectionKind::getMetadata());
751   DwarfLocSection =
752       Ctx->getWasmSection(".debug_loc", SectionKind::getMetadata());
753   DwarfAbbrevSection =
754       Ctx->getWasmSection(".debug_abbrev", SectionKind::getMetadata());
755   DwarfARangesSection = Ctx->getWasmSection(".debug_aranges", SectionKind::getMetadata());
756   DwarfRangesSection =
757       Ctx->getWasmSection(".debug_ranges", SectionKind::getMetadata());
758   DwarfMacinfoSection =
759       Ctx->getWasmSection(".debug_macinfo", SectionKind::getMetadata());
760   DwarfAddrSection = Ctx->getWasmSection(".debug_addr", SectionKind::getMetadata());
761   DwarfCUIndexSection = Ctx->getWasmSection(".debug_cu_index", SectionKind::getMetadata());
762   DwarfTUIndexSection = Ctx->getWasmSection(".debug_tu_index", SectionKind::getMetadata());
763   DwarfInfoSection =
764       Ctx->getWasmSection(".debug_info", SectionKind::getMetadata());
765   DwarfFrameSection = Ctx->getWasmSection(".debug_frame", SectionKind::getMetadata());
766   DwarfPubNamesSection = Ctx->getWasmSection(".debug_pubnames", SectionKind::getMetadata());
767   DwarfPubTypesSection = Ctx->getWasmSection(".debug_pubtypes", SectionKind::getMetadata());
768 
769   // Wasm use data section for LSDA.
770   // TODO Consider putting each function's exception table in a separate
771   // section, as in -function-sections, to facilitate lld's --gc-section.
772   LSDASection = Ctx->getWasmSection(".rodata.gcc_except_table",
773                                     SectionKind::getReadOnlyWithRel());
774 
775   // TODO: Define more sections.
776 }
777 
778 void MCObjectFileInfo::initXCOFFMCObjectFileInfo(const Triple &T) {
779   // The default csect for program code. Functions without a specified section
780   // get placed into this csect. The choice of csect name is not a property of
781   // the ABI or object file format. For example, the XL compiler uses an unnamed
782   // csect for program code.
783   TextSection = Ctx->getXCOFFSection(
784       ".text", XCOFF::StorageMappingClass::XMC_PR, XCOFF::XTY_SD,
785       XCOFF::C_HIDEXT, SectionKind::getText());
786 
787   DataSection = Ctx->getXCOFFSection(
788       ".data", XCOFF::StorageMappingClass::XMC_RW, XCOFF::XTY_SD,
789       XCOFF::C_HIDEXT, SectionKind::getData());
790 
791   ReadOnlySection = Ctx->getXCOFFSection(
792       ".rodata", XCOFF::StorageMappingClass::XMC_RO, XCOFF::XTY_SD,
793       XCOFF::C_HIDEXT, SectionKind::getReadOnly());
794 }
795 
796 void MCObjectFileInfo::InitMCObjectFileInfo(const Triple &TheTriple, bool PIC,
797                                             MCContext &ctx,
798                                             bool LargeCodeModel) {
799   PositionIndependent = PIC;
800   Ctx = &ctx;
801 
802   // Common.
803   CommDirectiveSupportsAlignment = true;
804   SupportsWeakOmittedEHFrame = true;
805   SupportsCompactUnwindWithoutEHFrame = false;
806   OmitDwarfIfHaveCompactUnwind = false;
807 
808   FDECFIEncoding = dwarf::DW_EH_PE_absptr;
809 
810   CompactUnwindDwarfEHFrameOnly = 0;
811 
812   EHFrameSection = nullptr;             // Created on demand.
813   CompactUnwindSection = nullptr;       // Used only by selected targets.
814   DwarfAccelNamesSection = nullptr;     // Used only by selected targets.
815   DwarfAccelObjCSection = nullptr;      // Used only by selected targets.
816   DwarfAccelNamespaceSection = nullptr; // Used only by selected targets.
817   DwarfAccelTypesSection = nullptr;     // Used only by selected targets.
818 
819   TT = TheTriple;
820 
821   switch (TT.getObjectFormat()) {
822   case Triple::MachO:
823     Env = IsMachO;
824     initMachOMCObjectFileInfo(TT);
825     break;
826   case Triple::COFF:
827     if (!TT.isOSWindows())
828       report_fatal_error(
829           "Cannot initialize MC for non-Windows COFF object files.");
830 
831     Env = IsCOFF;
832     initCOFFMCObjectFileInfo(TT);
833     break;
834   case Triple::ELF:
835     Env = IsELF;
836     initELFMCObjectFileInfo(TT, LargeCodeModel);
837     break;
838   case Triple::Wasm:
839     Env = IsWasm;
840     initWasmMCObjectFileInfo(TT);
841     break;
842   case Triple::XCOFF:
843     Env = IsXCOFF;
844     initXCOFFMCObjectFileInfo(TT);
845     break;
846   case Triple::UnknownObjectFormat:
847     report_fatal_error("Cannot initialize MC for unknown object file format.");
848     break;
849   }
850 }
851 
852 MCSection *MCObjectFileInfo::getDwarfComdatSection(const char *Name,
853                                                    uint64_t Hash) const {
854   switch (TT.getObjectFormat()) {
855   case Triple::ELF:
856     return Ctx->getELFSection(Name, ELF::SHT_PROGBITS, ELF::SHF_GROUP, 0,
857                               utostr(Hash));
858   case Triple::MachO:
859   case Triple::COFF:
860   case Triple::Wasm:
861   case Triple::XCOFF:
862   case Triple::UnknownObjectFormat:
863     report_fatal_error("Cannot get DWARF comdat section for this object file "
864                        "format: not implemented.");
865     break;
866   }
867   llvm_unreachable("Unknown ObjectFormatType");
868 }
869 
870 MCSection *
871 MCObjectFileInfo::getStackSizesSection(const MCSection &TextSec) const {
872   if (Env != IsELF)
873     return StackSizesSection;
874 
875   const MCSectionELF &ElfSec = static_cast<const MCSectionELF &>(TextSec);
876   unsigned Flags = ELF::SHF_LINK_ORDER;
877   StringRef GroupName;
878   if (const MCSymbol *Group = ElfSec.getGroup()) {
879     GroupName = Group->getName();
880     Flags |= ELF::SHF_GROUP;
881   }
882 
883   const MCSymbol *Link = TextSec.getBeginSymbol();
884   auto It = StackSizesUniquing.insert({Link, StackSizesUniquing.size()});
885   unsigned UniqueID = It.first->second;
886 
887   return Ctx->getELFSection(".stack_sizes", ELF::SHT_PROGBITS, Flags, 0,
888                             GroupName, UniqueID, cast<MCSymbolELF>(Link));
889 }
890