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