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