[yaml2obj/obj2yaml] - Improve dumping/creating of ELF versioning sections.

[grimar]

Summary

This makes the following improvements.

For SHT_GNU_versym:

• yaml2obj: set sh_link to index of .dynsym section automatically.

For SHT_GNU_verdef:

• yaml2obj: set sh_link to index of .dynstr section automatically.
• yaml2obj: set sh_info field automatically.
• obj2yaml: don't dump the Info field when its value matches the number of version definitions.

For SHT_GNU_verneed:

• yaml2obj: set sh_link to index of .dynstr section automatically.
• yaml2obj: set sh_info field automatically.
• obj2yaml: don't dump the Info field when its value matches the number of version dependencies.

Also, simplifies few test cases.

[jhenderson]

Looks to me like you need additional testing for when .dynsym or .dynstr are either not emitted at all, or are excluded from the section header table.

[grimar]

• Added test cases.

[jhenderson]

LGTM.

lld/test/ELF/invalid/verneed-shared.test

 ## REQUIRES: x86
 ## Test that we can parse SHT_GNU_verneed in a shared object and report certain errors.
 
 # RUN: echo '.globl _start; _start:' | llvm-mc -filetype=obj -triple=x86_64 - -o %t.o
 
 ## sh_offset(SHT_GNU_verneed) is out of bounds.
 # RUN: yaml2obj --docnum=1 %s -o %t1.so
 # RUN: not ld.lld %t.o %t1.so -o /dev/null 2>&1 | FileCheck --check-prefix=SHOFFSET %s
 # SHOFFSET: error: {{.*}}.so: section [index 1] has a sh_offset (0xffffffff) + sh_size (0x0) that is greater than the file size (0x168)
 --- !ELF
 FileHeader:
   Class:   ELFCLASS64
   Data:    ELFDATA2LSB
   Type:    ET_DYN
   Machine: EM_X86_64
 Sections:
-  - Name:  .gnu.version_r
-    Type:  SHT_GNU_verneed
-    Flags: [ SHF_ALLOC ]
-    Info:  1
+  - Name:     .gnu.version_r
+    Type:     SHT_GNU_verneed
+    Flags:    [ SHF_ALLOC ]
     ShOffset: 0xFFFFFFFF
 
 ## A Verneed entry is misaligned (not a multiple of 4). This may happen
 ## some interface shared objects. We use memcpy to read the fields, so
 ## misalignment isn't a problem and there is no need to diagnose.
 # RUN: yaml2obj --docnum=2 %s -o %t2.so
 # RUN: ld.lld %t.o %t2.so -o /dev/null
 --- !ELF
 FileHeader:
   Class:   ELFCLASS64
   Data:    ELFDATA2LSB
   Type:    ET_DYN
   Machine: EM_X86_64
 Sections:
   - Type: Fill
     Size: 0x1
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
-    Info:  1
-    Link:  .dynstr
     Dependencies:
       - Version: 1
         File:    foo
         Entries:
           - Name:  'foo'
             Hash:  0
             Flags: 0
             Other: 0
FileHeader:
   Data:    ELFDATA2LSB
   Type:    ET_DYN
   Machine: EM_X86_64
 Sections:
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
     Info:  1
-    Link:  .dynstr
     Content: "[[VERNEED]]"
 DynamicSymbols:
   - Name: foo
 
 ## vn_aux is misaligned.
 # RUN: yaml2obj --docnum=3 -D VERNEED=0100010001000000110000000000000000000000 %s -o %t4.so
 # RUN: not ld.lld %t.o %t4.so -o /dev/null 2>&1 | FileCheck --check-prefix=AUX-MISALIGNED %s
 # AUX-MISALIGNED: {{.*}}.so has an invalid Vernaux
 
 ## vna_name is out of bounds.
 # RUN: yaml2obj --docnum=3 -D VERNEED=010001000000000010000000000000009107000000000000ff00000000000000 %s -o %t5.so
 # RUN: not ld.lld %t.o %t5.so -o /dev/null 2>&1 | FileCheck --check-prefix=NAME-OOB %s
 # NAME-OOB: {{.*}}.so has a Vernaux with an invalid vna_name

llvm/include/llvm/ObjectYAML/ELFYAML.h

 struct VerneedEntry {
   uint16_t Version;
   StringRef File;
   std::vector<VernauxEntry> AuxV;
 };
 
 struct VerneedSection : Section {
   Optional<std::vector<VerneedEntry>> VerneedV;
-  llvm::yaml::Hex64 Info;
+  Optional<llvm::yaml::Hex64> Info;
 
   VerneedSection() : Section(ChunkKind::Verneed) {}
 
   std::vector<std::pair<StringRef, bool>> getEntries() const override {
     return {{"Dependencies", VerneedV.hasValue()}};
   };
 
   static bool classof(const Chunk *S) {
struct VerdefEntry {
   Optional<uint16_t> Flags;
   Optional<uint16_t> VersionNdx;
   Optional<uint32_t> Hash;
   std::vector<StringRef> VerNames;
 };
 
 struct VerdefSection : Section {
   Optional<std::vector<VerdefEntry>> Entries;
-
-  llvm::yaml::Hex64 Info;
+  Optional<llvm::yaml::Hex64> Info;
 
   VerdefSection() : Section(ChunkKind::Verdef) {}
 
   std::vector<std::pair<StringRef, bool>> getEntries() const override {
     return {{"Entries", Entries.hasValue()}};
   };
 
   static bool classof(const Chunk *S) { return S->Kind == ChunkKind::Verdef; }

llvm/lib/ObjectYAML/ELFEmitter.cpp

void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
   }
   SHeader.sh_size = SHeader.sh_entsize * Section.Members->size();
 }
 
 template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::SymverSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
+  unsigned Link = 0;
+  if (!Section.Link && !ExcludedSectionHeaders.count(".dynsym") &&
+      SN2I.lookup(".dynsym", Link))
+    SHeader.sh_link = Link;
+
   if (!Section.Entries)
     return;
 
   for (uint16_t Version : *Section.Entries)
     CBA.write<uint16_t>(Version, ELFT::TargetEndianness);
   SHeader.sh_size = Section.Entries->size() * SHeader.sh_entsize;
 }
 
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 
   SHeader.sh_size = (2 + Section.Bucket->size() + Section.Chain->size()) * 4;
 }
 
 template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::VerdefSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
-  SHeader.sh_info = Section.Info;
+
+  if (Section.Info)
+    SHeader.sh_info = *Section.Info;
+  else if (Section.Entries)
+    SHeader.sh_info = Section.Entries->size();
+
+  unsigned Link = 0;
+  if (!Section.Link && !ExcludedSectionHeaders.count(".dynstr") &&
+      SN2I.lookup(".dynstr", Link))
+    SHeader.sh_link = Link;
 
   if (!Section.Entries)
     return;
 
   uint64_t AuxCnt = 0;
   for (size_t I = 0; I < Section.Entries->size(); ++I) {
     const ELFYAML::VerdefEntry &E = (*Section.Entries)[I];
 
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
   SHeader.sh_size = Section.Entries->size() * sizeof(Elf_Verdef) +
                     AuxCnt * sizeof(Elf_Verdaux);
 }
 
 template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::VerneedSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
-  SHeader.sh_info = Section.Info;
+  if (Section.Info)
+    SHeader.sh_info = *Section.Info;
+  else if (Section.VerneedV)
+    SHeader.sh_info = Section.VerneedV->size();
+
+  unsigned Link = 0;
+  if (!Section.Link && !ExcludedSectionHeaders.count(".dynstr") &&
+      SN2I.lookup(".dynstr", Link))
+    SHeader.sh_link = Link;
 
   if (!Section.VerneedV)
     return;
 
   uint64_t AuxCnt = 0;
   for (size_t I = 0; I < Section.VerneedV->size(); ++I) {
     const ELFYAML::VerneedEntry &VE = (*Section.VerneedV)[I];
 

llvm/lib/ObjectYAML/ELFYAML.cpp

static void sectionMapping(IO &IO, ELFYAML::GnuHashSection &Section) {
   IO.mapOptional("HashValues", Section.HashValues);
 }
 static void sectionMapping(IO &IO, ELFYAML::NoBitsSection &Section) {
   commonSectionMapping(IO, Section);
 }
 
 static void sectionMapping(IO &IO, ELFYAML::VerdefSection &Section) {
   commonSectionMapping(IO, Section);
-  IO.mapRequired("Info", Section.Info);
+  IO.mapOptional("Info", Section.Info);
   IO.mapOptional("Entries", Section.Entries);
 }
 
 static void sectionMapping(IO &IO, ELFYAML::SymverSection &Section) {
   commonSectionMapping(IO, Section);
   IO.mapOptional("Entries", Section.Entries);
 }
 
 static void sectionMapping(IO &IO, ELFYAML::VerneedSection &Section) {
   commonSectionMapping(IO, Section);
-  IO.mapRequired("Info", Section.Info);
+  IO.mapOptional("Info", Section.Info);
   IO.mapOptional("Dependencies", Section.VerneedV);
 }
 
 static void sectionMapping(IO &IO, ELFYAML::RelocationSection &Section) {
   commonSectionMapping(IO, Section);
   IO.mapOptional("Info", Section.RelocatableSec, StringRef());
   IO.mapOptional("Relocations", Section.Relocations);
 }

llvm/test/Object/invalid.test

FileHeader:
   OSABI:   ELFOSABI_FREEBSD
   Type:    ET_DYN
   Machine: EM_X86_64
 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     EntSize: 0x0000000000000003
     Entries: [ ]
-    Link:    .dynsym
 ## Needed to trigger creation of .dynsym.
 DynamicSymbols:
   - Name:    foo
     Binding: STB_GLOBAL
 
 ## Check the case when e_shstrndx == SHN_XINDEX, but null section's sh_link contains
 ## the index of a section header string table that is larger than the number of the sections.
 

llvm/test/tools/llvm-objdump/ELF/verdef.test

FileHeader:
   Type:            ET_DYN
   Machine:         EM_X86_64
   Entry:           0x0000000000001000
 Sections:
   - Name:            .gnu.version_d
     Type:            SHT_GNU_verdef
     Flags:           [ SHF_ALLOC ]
     Address:         0x0000000000000230
-    Link:            .dynstr
     AddressAlign:    0x0000000000000004
-    Info:            0x0000000000000003
     Entries:
       - Version:         1
         Flags:           1
         VersionNdx:      1
         Hash:            123456789
         Names:
           - foo
       - Version:         1

llvm/test/tools/llvm-objdump/ELF/verneed.test

FileHeader:
   Entry:           0x0000000000201000
 Sections:
   - Name:            .gnu.version_r
     Type:            SHT_GNU_verneed
     Flags:           [ SHF_ALLOC ]
     Address:         0x0000000000200250
     Link:            .dynstr
     AddressAlign:    0x0000000000000004
-    Info:            0x0000000000000002
     Dependencies:
       - Version:         1
         File:            dso.so.0
         Entries:
           - Name:            v1
             Hash:            1234
             Flags:           10
             Other:           3

llvm/test/tools/llvm-readobj/ELF/all.test

Sections:
   - Name: .data
     Type: SHT_PROGBITS
   - Name: .rela.data
     Type: SHT_REL
     Relocations:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     Entries: [ 0 ]
-    Link:    .dynsym
   - Name:    .gnu.version_d
     Type:    SHT_GNU_verdef
-    Info:    0x0
     Entries: []
   - Name: .gnu.version_r
     Type: SHT_GNU_verneed
-    Info: 0x0
     Dependencies:
       - Version: 1
         File:    verneed1.so.0
         Entries: []
   - Name:         .dynamic
     Type:         SHT_DYNAMIC
     Address:      0x1000
     AddressAlign: 0x1000

llvm/test/tools/llvm-readobj/ELF/dyn-symbols.test

- Name:         .gnu.version
     Link:         .dynsym
     AddressAlign: 0x2
     EntSize:      0x2
 ## 0x8000 is a special VERSYM_HIDDEN bit.
     Entries:      [ 0, 1, 2, 0x8003 ]
   - Name:         .gnu.version_d
     Type:         SHT_GNU_verdef
     Flags:        [ SHF_ALLOC ]
-    Link:         .dynstr
     AddressAlign: 0x4
-    Info:         0x2
     Entries:
       - VersionNdx: 2
         Names:
           - Default
       - VersionNdx: 3
         Names:
           - NonDefault
 DynamicSymbols:

llvm/test/tools/llvm-readobj/ELF/hidden-versym.test

FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     Flags:   [ SHF_ALLOC ]
     Address: 0x0000000000200210
-    Link:    .dynsym
     Entries: [ 0, 0x8003 ]
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
-    Link:  .dynstr
-    Info:  0x0000000000000001
     Dependencies:
       - Version: 1
         File:    somefile
         Entries:
           - Name:  hiddensym
             Hash:  1234
             Flags: 0
             Other: 3
 DynamicSymbols:
   - Name:    h
     Binding: STB_GLOBAL

llvm/test/tools/llvm-readobj/ELF/merged.test

## An arbitrary valid note content.
   - Name:    .dynamic
     Type:    SHT_DYNAMIC
     Entries:
       - Tag:   DT_NULL
         Value: 0
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     Flags:   [ SHF_ALLOC ]
-    Link:    .dynsym
     Entries: [ 0, 1 ]
 DynamicSymbols:
   - Name:    foo
     Binding: STB_GLOBAL
 
 ## llvm-readobj does not support merged args, because it also supports some old
 ## flags (-st, -sd, etc.), and it would be confusing if only some merged args
 ## were supported.
 # RUN: not llvm-readobj -aeWhSrnudlVgIs %t.o 2>&1 | FileCheck %s --check-prefix=UNKNOWN
 
 # CHECK-NOT: Unknown command line argument
 # UNKNOWN:   for the --section-headers option: may only occur zero or one times!

llvm/test/tools/llvm-readobj/ELF/reloc-symbol-with-versioning.test

 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     Flags:   [ SHF_ALLOC ]
     Entries: [ 0, 2, 3, 4, 2, 1 ]
   - Name:         .gnu.version_r
     Type:         SHT_GNU_verneed
     Flags:        [ SHF_ALLOC ]
-    Link:         .dynstr
     AddressAlign: 0x0000000000000004
-    Info:         0x0000000000000002
     Dependencies:
       - Version: 1
         File:    verneed1.so.0
         Entries:
           - Name:  v2
             Hash:  1938
             Flags: 0
             Other: 3

llvm/test/tools/llvm-readobj/ELF/section-types.test

- Name: .phdrs
     Type: SHT_LLVM_PART_PHDR
   - Name: gnu_attributes
     Type: SHT_GNU_ATTRIBUTES
   - Name: gnu_hash
     Type: SHT_GNU_HASH
     Content: ""
   - Name: gnu_verdef
     Type: SHT_GNU_verdef
-    Info: 0
     Entries:
   - Name: gnu_verneed
     Type: SHT_GNU_verneed
-    Info: 0
     Dependencies:
   - Name: unknown
     Type: 0x1000
   - Name: loos
     Type: 0x60000000
   - Name: fooos
     Type: 0x60000F00
   - Name: hios

llvm/test/tools/llvm-readobj/ELF/verdef-invalid.test

 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
   - Name:    .gnu.version_d
     Type:    SHT_GNU_verdef
     Link:    [[LINK]]
-    Info:    0x0
     Entries: []
 
 ## Check that we report a warning when the sh_link field of a SHT_GNU_verdef section references a non-string table section.
 
 # RUN: yaml2obj %s --docnum=1 -DLINK=0x0 -o %t2
 # RUN: llvm-readobj -V %t2 2>&1 | FileCheck %s --check-prefix=INVALID-STRING-TABLE -DFILE=%t2
 # RUN: llvm-readelf -V %t2 2>&1 | FileCheck %s --check-prefix=INVALID-STRING-TABLE -DFILE=%t2
 

 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
   - Name:     .gnu.version_d
     Type:     SHT_GNU_verdef
-    Link:     .dynstr
-    Info:     0x0
     Entries:  []
     ShOffset: [[SHOFFSET=<none>]]
     ShName:   [[SHNAME=<none>]]
   - Name:   .dynstr
     Type:   SHT_STRTAB
     ShName: [[DYNSTRNAME=<none>]]
 DynamicSymbols:
   - Name: foo

 # DEF-PAST-END: warning: '[[FILE]]': invalid SHT_GNU_verdef section with index 1: version definition 1 goes past the end of the section
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
-  - Name:    .gnu.version_d
-    Type:    SHT_GNU_verdef
-    Link:    .dynstr
-    Info:    0x1
+  - Name: .gnu.version_d
+    Type: SHT_GNU_verdef
     Entries:
       - Names:
           - FOO
     ShSize: 1
 DynamicSymbols:
   - Name: foo
 
 ## Check that we report a warning when a SHT_GNU_verdef section contains a version definition
 ## that refers to an auxiliary entry that goes past the end of the section.
 
 # RUN: yaml2obj %s --docnum=4 -o %t5
 # RUN: llvm-readobj -V %t5 2>&1 | FileCheck %s --check-prefix=AUX-PAST-END -DFILE=%t5
 # RUN: llvm-readelf -V %t5 2>&1 | FileCheck %s --check-prefix=AUX-PAST-END -DFILE=%t5
 
 # AUX-PAST-END: warning: '[[FILE]]': invalid SHT_GNU_verdef section with index 1: version definition 1 refers to an auxiliary entry that goes past the end of the section
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
-  - Name:    .gnu.version_d
-    Type:    SHT_GNU_verdef
-    Link:    .dynstr
-    Info:    0x1
+  - Name: .gnu.version_d
+    Type: SHT_GNU_verdef
     Entries:
       - Names:
           - FOO
     ShSize: 21
 DynamicSymbols:
   - Name: foo
 
 ## Check that we can dump a SHT_GNU_verdef section properly even if it contains version names strings

 # PAST-STRTAB-END-GNU-NEXT:   0x0000: Rev: 1  Flags: none  Index: 0  Cnt: 1  Name: <invalid vda_name: 5>
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
-  - Name:    .gnu.version_d
-    Type:    SHT_GNU_verdef
-    Link:    .strtab
-    Info:    0x1
+  - Name: .gnu.version_d
+    Type: SHT_GNU_verdef
+    Link: .strtab
     Entries:
       - Names:
           - FOO
   - Name: .strtab
     Type: SHT_STRTAB
 DynamicSymbols:
   - Name: BAR
 

 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
   - Name:         .gnu.version
     Type:         SHT_GNU_versym
     Flags:        [ SHF_ALLOC ]
-    Link:         .dynsym
     AddressAlign: 0x0000000000000002
     EntSize:      0x0000000000000002
     Entries:      [ 0, 2 ]
   - Name:         .gnu.version_d
     Type:         SHT_GNU_verdef
     Flags:        [ SHF_ALLOC ]
-    Link:         .dynstr
     AddressAlign: 0x4
     Info:         0x1
     Entries: []
 DynamicSymbols:
   - Name:    foo
     Binding: STB_GLOBAL

llvm/test/tools/llvm-readobj/ELF/verneed-flags.yaml

 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
   Entry: 0x0000000000201000
 Sections:
-  - Name:            .gnu.version_r
-    Type:            SHT_GNU_verneed
-    Link:            .dynstr
-    Info:            0x0000000000000001
+  - Name: .gnu.version_r
+    Type: SHT_GNU_verneed
     Dependencies:
       - Version:         1
         File:            dso.so.0
         Entries:
           - Name:            base
             Hash:            0
             Flags:           0x1
             Other:           0

llvm/test/tools/llvm-readobj/ELF/verneed-invalid.test

FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     Flags:   [ SHF_ALLOC ]
     Address: 0x200210
-    Link:    .dynsym
     Entries: [ 0, 2 ]
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
-    Link:  .dynstr
-    Info:  1
     AddressAlign: 4
     Dependencies:
       - Version:   1
         File:      somefile
         Entries:
           - Name:  '' ## invalid name
             Hash:  0
             Flags: 0

 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     Flags:   [ SHF_ALLOC ]
-    Link:    .dynsym
     Entries: [ 0, 2 ]
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
     Link:  0
-    Info:  1
     AddressAlign: 4
     Dependencies:
       - Version: 1
         File:    somefile
         Entries:
           - Name:  'bar'
             Hash:  0
             Flags: 0

 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     Flags:   [ SHF_ALLOC ]
-    Link:    .dynsym
     Entries: [ 2 ]
   - Name:         .gnu.version_r
     Type:         SHT_GNU_verneed
     Flags:        [ SHF_ALLOC ]
     Info:         1
-    Link:         .dynstr
     AddressAlign: 4
 ## The byte offset to the auxiliary entry is 0x11, i.e. it is not correctly aligned in memory.
     Content: "0100010001000000110000000000000000000000"
 DynamicSymbols: []
 
 ## Here we check that we can properly dump the case when a dependency file name
 ## and/or a dependency name string offset is equal to the string table size.
 ##
FileHeader:
   Type:  ET_EXEC
 Sections:
   - Name: .mystrtab
     Type: SHT_STRTAB
     Content: "00"
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
-    Info:  1
     Link:  .mystrtab
     AddressAlign: 4
     Dependencies:
       - Version: 1
         File:    foo
         Entries:
           - Name:  'foo'
             Hash:  0
FileHeader:
   Type:  ET_EXEC
 Sections:
   - Name: .mystrtab
     Type: SHT_STRTAB
     Content: ""
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
-    Info:  1
     Link:  .mystrtab
     AddressAlign: 4
     Dependencies:
       - Version: 1
         File:    foo
         Entries:
           - Name:  'foo'
             Hash:  0

 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:   .gnu.version_r
     Type:   SHT_GNU_verneed
     Flags:  [ SHF_ALLOC ]
-    Info:   1
     Link:   [[LINK=.dynstr]]
     ShName: [[SHNAME=<none>]]
     Dependencies:
       - Version: 1
         File:    foo
         Entries:
           - Name:  'foo'
             Hash:  0

 # INVALID-DATA: warning: '[[FILE]]': cannot read content of SHT_GNU_verneed section with index 1: section [index 1] has a sh_offset (0xffffffff) + sh_size (0x0) that is greater than the file size (0x228)
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
-  - Name:  .gnu.version_r
-    Type:  SHT_GNU_verneed
-    Flags: [ SHF_ALLOC ]
-    Info:  1
-    Link:  .dynstr
+  - Name:     .gnu.version_r
+    Type:     SHT_GNU_verneed
+    Flags:    [ SHF_ALLOC ]
     ShOffset: 0xFFFFFFFF
 ## Triggers creation of the .dynstr.
 DynamicSymbols:
   - Name: foo
 
 ## Check that we report a warning when a SHT_GNU_verneed section contains a version dependency
 ## that goes past the end of the section.
 
 # RUN: yaml2obj --docnum=8 %s -o %t8
 # RUN: llvm-readobj --sections -V %t8 2>&1 | FileCheck %s -DFILE=%t8 --check-prefix=DEP-PAST-END
 # RUN: llvm-readelf --sections -V %t8 2>&1 | FileCheck %s -DFILE=%t8 --check-prefix=DEP-PAST-END
 
 # DEP-PAST-END: warning: '[[FILE]]': invalid SHT_GNU_verneed section with index 1: version dependency 1 goes past the end of the section
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
-  - Name:  .gnu.version_r
-    Type:  SHT_GNU_verneed
-    Flags: [ SHF_ALLOC ]
-    Info:  1
-    Link:  .dynstr
+  - Name:   .gnu.version_r
+    Type:   SHT_GNU_verneed
+    Flags:  [ SHF_ALLOC ]
     ShSize: 0x1
     Dependencies:
       - Version: 1
         File:    foo
         Entries:
           - Name:  'foo'
             Hash:  0
             Flags: 0
FileHeader:
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Type: Fill
     Size: 0x1
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
-    Info:  1
     Link:  .dynstr
     Dependencies:
       - Version: 1
         File:    foo
         Entries:
           - Name:  'foo'
             Hash:  0
             Flags: 0

 # AUX-PAST-END: warning: '[[FILE]]': invalid SHT_GNU_verneed section with index 1: version dependency 1 refers to an auxiliary entry that goes past the end of the section
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
-  - Name:  .gnu.version_r
-    Type:  SHT_GNU_verneed
-    Flags: [ SHF_ALLOC ]
-    Info:  1
-    Link:  .dynstr
+  - Name:   .gnu.version_r
+    Type:   SHT_GNU_verneed
+    Flags:  [ SHF_ALLOC ]
     ShSize: 21
     Dependencies:
       - Version: 1
         File:    foo
         Entries:
           - Name:  'foo'
             Hash:  0
             Flags: 0
FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
     Info:  1
-    Link:  .dynstr
 ## The byte offset to the auxiliary entry is 0x11, i.e. it is not correctly aligned in memory.
     Content: "0100010001000000110000000000000000000000"
 DynamicSymbols:
   - Name: foo
 
 ## Check how we handle the case when a dependency definition entry has an unsupported version.
 
 # RUN: yaml2obj %s --docnum=12 -o %t12
 # RUN: llvm-readobj -V %t12 2>&1 | FileCheck %s --check-prefix=UNSUPPORTED-VERSION -DFILE=%t12
 # RUN: llvm-readelf -V %t12 2>&1 | FileCheck %s --check-prefix=UNSUPPORTED-VERSION -DFILE=%t12
 
 # UNSUPPORTED-VERSION: warning: '[[FILE]]': unable to dump SHT_GNU_verneed section with index 1: version 65278 is not yet supported
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:  .gnu.version_r
     Type:  SHT_GNU_verneed
     Flags: [ SHF_ALLOC ]
-    Info:  1
-    Link:  .dynstr
     Dependencies:
       - Version: 0xfefe
         File:    foo
         Entries:
           - Name:  'foo'
             Hash:  0
             Flags: 0
             Other: 0

 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     Flags:   [ SHF_ALLOC ]
-    Link:    .dynsym
     Entries: [ 0, 2 ]
-  - Name:         .gnu.version_r
-    Type:         SHT_GNU_verneed
-    Flags:        [ SHF_ALLOC ]
-    Link:         .custom.dynstr
-    Info:         1
+  - Name:  .gnu.version_r
+    Type:  SHT_GNU_verneed
+    Flags: [ SHF_ALLOC ]
+    Link:  .custom.dynstr
     AddressAlign: 4
     Dependencies:
       - Version: 1
         File:    zed
         Entries:
           - Name:  'bar'
             Hash:  0
             Flags: 0
             Other: 2
   - Name: .custom.dynstr
     Type: SHT_STRTAB
     Content: "6162636465666768696a00" ## 'a','b','c','d','e','f','g','h','i','j',NIL
 DynamicSymbols:
   - Name:    foo
     Binding: STB_GLOBAL

llvm/test/tools/llvm-readobj/ELF/versioninfo.test

FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   OSABI: ELFOSABI_FREEBSD
   Type:  ET_DYN
 Sections:
   - Name:         .gnu.version
     Type:         SHT_GNU_versym
     Flags:        [ SHF_ALLOC ]
-    Link:         .dynsym
     AddressAlign: 0x0000000000000002
-    EntSize:      0x0000000000000002
     Entries:      [ 0, 2, 3, 4, 5, 6]
   - Name:         .gnu.version_d
     Type:         SHT_GNU_verdef
     Flags:        [ SHF_ALLOC ]
-    Link:         .dynstr
     AddressAlign: 0x0000000000000004
-    Info:         0x0000000000000006
     Entries:
       - Names:
           - VERSION1
       - Flags: 1
         Names:
           - VERSION1
       - Flags: 2
         Names:
Entries:
         Hash:       175630258
         Names:
           - VERSION2
           - VERSION1
           - VERSION3
   - Name:         .gnu.version_r
     Type:         SHT_GNU_verneed
     Flags:        [ SHF_ALLOC ]
-    Link:         .dynstr
     AddressAlign: 0x0000000000000004
-    Info:         0x0000000000000002
     Dependencies:
       - Version: 1
         File:    verneed1.so.0
         Entries:
           - Name:  v1
             Hash:  0
             Flags: 1
             Other: 0

llvm/test/tools/llvm-readobj/ELF/versym-invalid.test

 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
-    Link:    .dynsym
     Entries: [ 0 ]
   - Name:    .dynstr
     Type:    SHT_NULL
 DynamicSymbols: []
 
 ## Check we report a warning when a SHT_GNU_versym section is not correctly aligned in memory.
 
 # RUN: yaml2obj --docnum=3 %s -DSHOFFSET=0xffff -o %t4

 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:     .gnu.version
     Type:     SHT_GNU_versym
     Entries:  [ 0 ]
-    Link:     .dynsym
     ShOffset: [[SHOFFSET=<none>]]
     ShName:   [[SHNAME=<none>]]
   - Name:   .dynsym
     Type:   SHT_DYNSYM
     ShName: [[DYNSYMNAME=<none>]]
 DynamicSymbols: []
 
 ## Check that llvm-readelf reports a warning when the name of the SHT_GNU_versym section can't be read.

 # RUN: llvm-readobj -V --dyn-syms %t5 2>&1 | FileCheck -DFILE=%t5 %s --check-prefix=INVALID-ENT-SIZE-LLVM
 
 # INVALID-ENT-SIZE-GNU:      Symbol table '.dynsym' contains 2 entries:
 # INVALID-ENT-SIZE-GNU-NEXT:    Num:    Value          Size Type    Bind   Vis       Ndx Name
 # INVALID-ENT-SIZE-GNU-NEXT: warning: '[[FILE]]': section [index 1] has invalid sh_entsize: expected 2, but got 3
 # INVALID-ENT-SIZE-GNU-NEXT:      0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT   UND @<corrupt>
 # INVALID-ENT-SIZE-GNU-NEXT:      1: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT   UND foo@<corrupt>
 # INVALID-ENT-SIZE-GNU:      Version symbols section '.gnu.version' contains 1 entries:
-# INVALID-ENT-SIZE-GNU-NEXT:  Addr: 0000000000000000  Offset: 0x000040  Link: 0 ()
+# INVALID-ENT-SIZE-GNU-NEXT:  Addr: 0000000000000000  Offset: 0x000040  Link: 2 (.dynsym)
 # INVALID-ENT-SIZE-GNU-NEXT: warning: '[[FILE]]': cannot read content of SHT_GNU_versym section with index 1: section [index 1] has invalid sh_entsize: expected 2, but got 3
 
 # INVALID-ENT-SIZE-LLVM:      DynamicSymbols [
 # INVALID-ENT-SIZE-LLVM-NEXT: warning: '[[FILE]]': section [index 1] has invalid sh_entsize: expected 2, but got 3
 # INVALID-ENT-SIZE-LLVM-NEXT:   Symbol {
 # INVALID-ENT-SIZE-LLVM-NEXT:     Name: @<corrupt> (0)
 # INVALID-ENT-SIZE-LLVM-NEXT:     Value: 0x0
 # INVALID-ENT-SIZE-LLVM-NEXT:     Size: 0

 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     Entries: [ 0, 1 ]
-    Link:   .dynsym
 DynamicSymbols:
   - Name: foo
   - Name: bar
 
 ## Check we can dump a SHT_GNU_versym section when it is linked to a custom dynamic symbol
 ## table that is not called ".dynsym".
 
 # RUN: yaml2obj --docnum=6 %s -o %t7

llvm/test/tools/obj2yaml/ELF/verdef-section.yaml

 ## Check how we dump SHT_GNU_verdef sections.
+## Check we don't dump the `Info` field when its value is equal
+## to the number of version definitions.
 
 # RUN: yaml2obj %s -o %t
 # RUN: obj2yaml %t | FileCheck %s
 
 # CHECK:       - Name:         .gnu.version_d
 # CHECK-NEXT:    Type:         SHT_GNU_verdef
 # CHECK-NEXT:    Flags:        [ SHF_ALLOC ]
 # CHECK-NEXT:    Address:      0x230
 # CHECK-NEXT:    Link:         .dynstr
 # CHECK-NEXT:    AddressAlign: 0x4
-# CHECK-NEXT:    Info:         0x4
+# INFO-NEXT:     Info:         0x4
 # CHECK-NEXT:    Entries:
 # CHECK-NEXT:      - Names:
 # CHECK-NEXT:          - VERSION_0
 # CHECK-NEXT:      - Flags:      2
 # CHECK-NEXT:        VersionNdx: 2
 # CHECK-NEXT:        Hash:       108387921
 # CHECK-NEXT:        Names:
 # CHECK-NEXT:          - VERSION_1
FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
   - Name:            .gnu.version_d
     Type:            SHT_GNU_verdef
     Flags:           [ SHF_ALLOC ]
     Address:         0x230
-    Link:            .dynstr
     AddressAlign:    0x4
-    Info:            0x4
+    Info:            [[INFO=<none>]]
     Entries:
 ## An entry that has all fields explicitly set to their default values.
 ## Used to check that we don't dump them.
       - Version:    [[VERSION=1]]
         Flags:      0
         VersionNdx: 0
         Hash:       0
         Names:
## Another entry with arbitrary values and version predecessors.
         Hash:       108387922
         Names:
           - VERSION_2
           - VERSION_3
           - VERSION_4
 ## Needed to emit the .dynstr section.
 DynamicSymbols: []
 
+## Check we dump the `Info` field when its value is not equal
+## to the number of version definitions.
+
+# RUN: yaml2obj %s -DINFO=0x4 -o %t.info
+# RUN: obj2yaml %t.info | FileCheck %s --check-prefixes=CHECK,INFO
+
 ## Document that we are not able to dump a version definition which
 ## has a version revision (vd_version) that is not equal to 1.
 
 # RUN: yaml2obj %s -DVERSION=2 -o %t.version
 # RUN: not obj2yaml %t.version 2>&1 | \
 # RUN:   FileCheck %s -DFILE=%t.version --check-prefix=VERSION-ERR
 
 # VERSION-ERR: Error reading file: [[FILE]]: invalid SHT_GNU_verdef section version: 2

llvm/test/tools/obj2yaml/ELF/verneed-section.yaml

+## Check that we are able to yamalize the SHT_GNU_verneed section.
+## Check we don't dump the `Info` field when its value
+## is equal to the number of version dependencies.
+
 # RUN: yaml2obj %s -o %t
 # RUN: obj2yaml %t | FileCheck %s
 
-## Check we are able to yamalize SHT_GNU_verneed section.
-
 # CHECK:      - Name:            .gnu.version_r
 # CHECK-NEXT:   Type:            SHT_GNU_verneed
 # CHECK-NEXT:   Flags:           [ SHF_ALLOC ]
 # CHECK-NEXT:   Address:         0x200250
 # CHECK-NEXT:   Link:            .dynstr
 # CHECK-NEXT:   AddressAlign:    0x4
-# CHECK-NEXT:   Info:            0x2
+# INFO-NEXT:    Info:            0x3
 # CHECK-NEXT:   Dependencies:
 # CHECK-NEXT:     - Version:         1
 # CHECK-NEXT:       File:            dso.so.0
 # CHECK-NEXT:       Entries:
 # CHECK-NEXT:         - Name:            v1
 # CHECK-NEXT:           Hash:            1937
 # CHECK-NEXT:           Flags:           10
 # CHECK-NEXT:           Other:           3

 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
   Entry: 0x0000000000201000
 Sections:
-  - Name:            .gnu.version_r
-    Type:            SHT_GNU_verneed
-    Flags:           [ SHF_ALLOC ]
-    Address:         0x200250
-    Link:            .dynstr
-    AddressAlign:    4
-    Info:            2
+  - Name:         .gnu.version_r
+    Type:         SHT_GNU_verneed
+    Flags:        [ SHF_ALLOC ]
+    Address:      0x200250
+    AddressAlign: 4
+    Info:         [[INFO=<none>]]
     Dependencies:
       - Version:         1
         File:            dso.so.0
         Entries:
           - Name:            v1
             Hash:            1937
             Flags:           10
             Other:           3
           - Name:            v2
             Hash:            1938
             Flags:           11
             Other:           4
       - Version:         1
         File:            dso.so.1
         Entries:
           - Name:            v3
             Hash:            1939
             Flags:           12
             Other:           2
 DynamicSymbols:
   - Name:    f1
     Binding: STB_GLOBAL
+
+## Check we dump the `Info` field when its value
+## is not equal to the number of version dependencies.
+
+# RUN: yaml2obj %s -DINFO=0x3 -o %t.info
+# RUN: obj2yaml %t.info | FileCheck %s --check-prefixes=CHECK,INFO

llvm/test/tools/yaml2obj/ELF/override-shname.yaml

Sections:
   - Name: .group
     Type: SHT_GROUP
     ShName: 0x000000006
     Members:
   - Name: .gnu.version
     Type: SHT_GNU_versym
     Entries: [ ]
     ShName: 0x000000007
-  - Name: .gnu.version_r
-    Type: SHT_GNU_verneed
-    Info: 0x0000000000000001
+  - Name:   .gnu.version_r
+    Type:   SHT_GNU_verneed
     ShName: 0x000000008
     Dependencies:
   - Name: .gnu.version_d
     Type: SHT_GNU_verdef
-    Info: 0x0000000000000001
     ShName: 0x000000009
     Entries:
   - Name: .regular
     Type: SHT_PROGBITS
     ShName: 0x00000000A
   - Name: .strtab
     Type: SHT_STRTAB
     ShName: 0x00000000B

llvm/test/tools/yaml2obj/ELF/override-shoffset.yaml

Sections:
   - Name: .group
     Type: SHT_GROUP
     ShOffset: 0x000000006
     Members:
   - Name: .gnu.version
     Type: SHT_GNU_versym
     Entries: [ ]
     ShOffset: 0x000000007
-  - Name: .gnu.version_r
-    Type: SHT_GNU_verneed
-    Info: 0x0000000000000001
+  - Name:     .gnu.version_r
+    Type:     SHT_GNU_verneed
     ShOffset: 0x000000008
     Dependencies:
   - Name: .gnu.version_d
     Type: SHT_GNU_verdef
-    Info: 0x0000000000000001
     ShOffset: 0x000000009
     Entries:
   - Name: .regular
     Type: SHT_PROGBITS
     ShOffset: 0x00000000A
   - Name: .strtab
     Type: SHT_STRTAB
     ShOffset: 0x00000000B

llvm/test/tools/yaml2obj/ELF/override-shsize.yaml

Sections:
   - Name: .group
     Type: SHT_GROUP
     ShSize: 0x000000006
     Members:
   - Name: .gnu.version
     Type: SHT_GNU_versym
     Entries: [ ]
     ShSize: 0x000000007
-  - Name: .gnu.version_r
-    Type: SHT_GNU_verneed
-    Info: 0x0000000000000001
+  - Name:   .gnu.version_r
+    Type:   SHT_GNU_verneed
     ShSize: 0x000000008
     Dependencies:
   - Name: .gnu.version_d
     Type: SHT_GNU_verdef
-    Info: 0x0000000000000001
     ShSize: 0x000000009
     Entries:
   - Name: .regular
     Type: SHT_PROGBITS
     ShSize: 0x00000000A
   - Name: .strtab
     Type: SHT_STRTAB
     ShSize: 0x00000000B

llvm/test/tools/yaml2obj/ELF/override-shtype.yaml

FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
   - Name:   .gnu.version_r
     Type:   SHT_GNU_verneed
     Flags:  [ SHF_ALLOC ]
     ShType: [[TYPE=SHT_GNU_verneed]]
-    Info:   0
     Dependencies:
       - Version: 1
         File:    dso.so.0
         Entries:
           - Name:  v1
             Hash:  1937
             Flags: 0
             Other: 3
 DynamicSymbols: []

llvm/test/tools/yaml2obj/ELF/verdef-section.yaml

 ## Test how we create SHT_GNU_verdef sections.
 
+## Check that we link the SHT_GNU_verdef section to
+## the `.dynstr` section by default.
+## Check that we set the value of `sh_info` field to the
+## number of version definitions by default.
+
 # RUN: yaml2obj --docnum=1 %s -o %t1
 # RUN: llvm-readobj -V %t1 | FileCheck %s
+# RUN: llvm-readelf --sections %t1 | \
+# RUN:   FileCheck %s -DLINK=3 -DINFO=4 --check-prefix=FIELDS
+
+# FIELDS: [Nr] Name              Type   {{.*}} Flg Lk       Inf
+# FIELDS: [ 1] .gnu.version_d    VERDEF {{.*}}   A [[LINK]] [[INFO]]
+# FIELDS: [ 3] .dynstr
 
 # CHECK:      VersionDefinitions [
 # CHECK-NEXT:   Definition {
 # CHECK-NEXT:     Version: 1
 # CHECK-NEXT:     Flags [ (0x0)
 # CHECK-NEXT:     ]
 # CHECK-NEXT:     Index: 0
 # CHECK-NEXT:     Hash: 0

 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
   - Name:  .gnu.version_d
     Type:  SHT_GNU_verdef
     Flags: [ SHF_ALLOC ]
-    Link:  .dynstr
-    Info:  0x4
+    Info:  [[INFO=<none>]]
+    Link:  [[LINK=<none>]]
     Entries:
 ## Case 1: an entry that has no Version, Flags, VersionNdx or Hash fields set.
 ##         Used to check values that are written by default. Also shows
 ##         that we are able to use the "=<none>" syntax for these fields.
       - Version:    [[VERSION=<none>]]
         Flags:      [[FLAGS=<none>]]
         VersionNdx: [[VERNDX=<none>]]
         Hash:       [[HASH=<none>]]
##         all known flags as well as few unknown.
         Names:
           - VERSION_2
           - VERSION_3
           - VERSION_4
 DynamicSymbols:
   - Name:    foo
     Binding: STB_GLOBAL
 
+## Check that we are able to set sh_info and sh_link fields to arbitrary values.
+
+# RUN: yaml2obj --docnum=1 -DINFO=123 -DLINK=234 %s -o %t1.fields
+# RUN: llvm-readelf --sections %t1.fields | \
+# RUN:   FileCheck %s -DINFO=123 -DLINK=234 --check-prefix=FIELDS
+
 ## Check we are able to emit a version definition which has a version revision
 ## (vd_version) field value that is not equal to 1.
 
 # RUN: yaml2obj --docnum=1 -DVERSION=2 %s -o %t.version
 # RUN: llvm-readobj -V %t.version 2>&1 | FileCheck %s --check-prefix=VERSION-ERR
 
 # VERSION-ERR: unable to dump SHT_GNU_verdef section with index 1: version 2 is not yet supported
 
 ## Check we can use "Content" to describe the content.
+## Check we set the sh_link field to 0 when there is no .dynstr section.
 
 # RUN: yaml2obj --docnum=2 %s -o %t2
 # RUN: llvm-readobj --sections --section-data %t2 | FileCheck %s --check-prefix=CONTENT
 
 # CONTENT:      Name: .gnu.version_d
 # CONTENT-NEXT: Type: SHT_GNU_verdef
 # CONTENT-NEXT: Flags [ (0x2)
 # CONTENT-NEXT:   SHF_ALLOC (0x2)
 # CONTENT-NEXT: ]
 # CONTENT-NEXT: Address: 0x0
 # CONTENT-NEXT: Offset: 0x40
 # CONTENT-NEXT: Size: 3
 # CONTENT-NEXT: Link: 0
-# CONTENT-NEXT: Info: 1
+# CONTENT-NEXT: Info: 0
 # CONTENT-NEXT: AddressAlignment:
 # CONTENT-NEXT: EntrySize:
 # CONTENT-NEXT: SectionData (
 # CONTENT-NEXT:   0000: 112233
 # CONTENT-NEXT: )
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
   - Name:    .gnu.version_d
     Type:    SHT_GNU_verdef
     Flags:   [ SHF_ALLOC ]
-    Info:    0x0000000000000001
     Content: "112233"
 
 ## Check we can omit "Content" and "Entries" fields to produce an empty SHT_GNU_verdef section.
 
 # RUN: yaml2obj --docnum=3 %s -o %t3
 # RUN: llvm-readelf --sections %t3 | FileCheck %s --check-prefix=NO-PROPS
 
 # NO-PROPS: [Nr] Name           Type   Address          Off    Size   ES Flg Lk Inf Al
-# NO-PROPS: [ 1] .gnu.version_d VERDEF 0000000000000000 000040 000000 00   A 0   1  0
+# NO-PROPS: [ 1] .gnu.version_d VERDEF 0000000000000000 000040 000000 00   A 0   0  0
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
   - Name:  .gnu.version_d
     Type:  SHT_GNU_verdef
     Flags: [ SHF_ALLOC ]
-    Info:  0x0000000000000001
 
 ## Check we can use the "Content" key with the "Size" key when the size is greater
 ## than or equal to the content size.
 
 # RUN: not yaml2obj --docnum=4 -DSIZE=1 -DCONTENT="'0011'" %s 2>&1 | \
 # RUN:   FileCheck %s --check-prefix=CONTENT-SIZE-ERR
 
 # CONTENT-SIZE-ERR: error: Section size must be greater than or equal to the content size
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
   - Name:    .gnu.version_d
     Type:    SHT_GNU_verdef
-    Info:    0x1
     Size:    [[SIZE=<none>]]
     Content: [[CONTENT=<none>]]
     Entries: [[ENTRIES=<none>]]
 
 # RUN: yaml2obj --docnum=4 -DSIZE=2 -DCONTENT="'0011'" %s -o %t.cont.size.eq.o
 # RUN: llvm-readobj --sections --section-data %t.cont.size.eq.o | \
 # RUN:   FileCheck %s --check-prefix=CHECK-CONTENT -DDATA="0011"
 

 ## Check we can't use the "Entries" key together with the "Content" or "Size" keys.
 
 # RUN: not yaml2obj --docnum=4 -DSIZE=0 -DENTRIES="[]" %s 2>&1 | \
 # RUN:   FileCheck %s --check-prefix=ENTRIES-ERR
 # RUN: not yaml2obj --docnum=4 -DCONTENT="'00'" -DENTRIES="[]" %s 2>&1 | \
 # RUN:   FileCheck %s --check-prefix=ENTRIES-ERR
 
 # ENTRIES-ERR: error: "Entries" cannot be used with "Content" or "Size"
+
+## Check we set the sh_link field to 0 when the .dynstr section is excluded
+## from the section header table.
+
+# RUN: yaml2obj --docnum=5 %s -o %t5
+# RUN: llvm-readelf --sections %t5 | FileCheck %s --check-prefix=EXCLUDED
+
+# EXCLUDED: [Nr] Name           {{.*}} ES Flg Lk Inf
+# EXCLUDED: [ 1] .gnu.version_d {{.*}} 00     0   0
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_DYN
+Sections:
+  - Name: .gnu.version_d
+    Type: SHT_GNU_verdef
+  - Name: .dynstr
+    Type: SHT_STRTAB
+SectionHeaderTable:
+  Sections:
+    - Name: .gnu.version_d
+    - Name: .strtab
+    - Name: .shstrtab
+  Excluded:
+    - Name: .dynstr

llvm/test/tools/yaml2obj/ELF/verneed-section.yaml

-## Check we are able to handle SHT_GNU_verneed sections.
+## Check we are able to dump SHT_GNU_verneed sections properly.
+## Check that we link the SHT_GNU_verneed section to
+## the `.dynstr` section by default.
+## Check that we set the value of `sh_info` field to the number
+## of version dependencies by default.
 
 # RUN: yaml2obj --docnum=1 %s -o %t1
 # RUN: llvm-readobj -V %t1 | FileCheck %s
+# RUN: llvm-readelf --sections %t1 | \
+# RUN:   FileCheck %s -DLINK=3 -DINFO=2 --check-prefix=FIELDS
+
+# FIELDS: [Nr] Name           Type    {{.*}} Flg Lk       Inf      Al
+# FIELDS: [ 1] .gnu.version_r VERNEED {{.*}}   A [[LINK]] [[INFO]] 4
+# FIELDS: [ 3] .dynstr
 
 # CHECK:      VersionRequirements [
 # CHECK-NEXT:   Dependency {
 # CHECK-NEXT:     Version: 1
 # CHECK-NEXT:     Count: 2
 # CHECK-NEXT:     FileName: dso.so.0
 # CHECK-NEXT:     Entries [
 # CHECK-NEXT:       Entry {

 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
   Entry: 0x0000000000201000
 Sections:
-  - Name:            .gnu.version_r
-    Type:            SHT_GNU_verneed
-    Flags:           [ SHF_ALLOC ]
-    Address:         0x0000000000200250
-    Link:            .dynstr
-    AddressAlign:    0x0000000000000004
-    Info:            0x0000000000000002
+  - Name:         .gnu.version_r
+    Type:         SHT_GNU_verneed
+    Flags:        [ SHF_ALLOC ]
+    Address:      0x0000000000200250
+    AddressAlign: 0x0000000000000004
+    Info:         [[INFO=<none>]]
+    Link:         [[LINK=<none>]]
     Dependencies:
       - Version:         1
         File:            dso.so.0
         Entries:
           - Name:            v1
             Hash:            1937
             Flags:           10
             Other:           3
           - Name:            v2
             Hash:            1938
             Flags:           11
             Other:           4
       - Version:         1
         File:            dso.so.1
         Entries:
           - Name:            v3
             Hash:            1939
             Flags:           12
             Other:           2
 DynamicSymbols:
   - Name:    f1
     Binding: STB_GLOBAL
 
+## Check that we are able to set sh_info and sh_link fields to arbitrary values.
+
+# RUN: yaml2obj --docnum=1 -DINFO=123 -DLINK=234 %s -o %t1.fields
+# RUN: llvm-readelf --sections %t1.fields | \
+# RUN:   FileCheck %s -DINFO=123 -DLINK=234 --check-prefix=FIELDS
+
 ## Check we can omit "Content", "Size" and "Dependencies" fields to
 ## produce an empty SHT_GNU_verneed section.
+## Check we set the sh_link field to 0 when there is no .dynstr section.
 
 # RUN: yaml2obj --docnum=2 %s -o %t3
 # RUN: llvm-readelf --sections %t3 | FileCheck %s --check-prefix=NO-PROPS
 
-# NO-PROPS: [Nr] Name           Type    Address          Off    Size
-# NO-PROPS: [ 1] .gnu.version_r VERNEED 0000000000000000 000040 000000
+# NO-PROPS: [Nr] Name           Type    Address          Off    Size   ES Flg Lk Inf
+# NO-PROPS: [ 1] .gnu.version_r VERNEED 0000000000000000 000040 000000 00   A 0  0
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
 Sections:
-  - Name:  .gnu.version_r
-    Type:  SHT_GNU_verneed
-    Flags: [ SHF_ALLOC ]
-    Info:  0x0
+  - Name:         .gnu.version_r
+    Type:         SHT_GNU_verneed
+    Flags:        [ SHF_ALLOC ]
     Size:         [[SIZE=<none>]]
     Content:      [[CONTENT=<none>]]
     Dependencies: [[DEPS=<none>]]
 
 ## Check we can use the "Content" key with the "Size" key when the size is greater
 ## than or equal to the content size.
 
 # RUN: not yaml2obj --docnum=2 -DCONTENT="'00'" -DSIZE=0 %s 2>&1 | \

 ## Check we can't use the "Dependencies" key together with the "Content" or "Size" keys.
 
 # RUN: not yaml2obj --docnum=2 -DSIZE=0 -DDEPS="[]" %s 2>&1 | \
 # RUN:   FileCheck %s --check-prefix=DEPS-ERR
 # RUN: not yaml2obj --docnum=2 -DCONTENT="'00'" -DDEPS="[]" %s 2>&1 | \
 # RUN:   FileCheck %s --check-prefix=DEPS-ERR
 
 # DEPS-ERR: error: "Dependencies" cannot be used with "Content" or "Size"
+
+## Check we set the sh_link field to 0 when the .dynstr section is excluded
+## from the section header table.
+
+# RUN: yaml2obj --docnum=3 %s -o %t3
+# RUN: llvm-readelf --sections %t3 | FileCheck %s --check-prefix=EXCLUDED
+
+# EXCLUDED: [Nr] Name           {{.*}} ES Flg Lk Inf
+# EXCLUDED: [ 1] .gnu.version_r {{.*}} 00     0   0
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_DYN
+Sections:
+  - Name: .gnu.version_r
+    Type: SHT_GNU_verneed
+  - Name: .dynstr
+    Type: SHT_STRTAB
+SectionHeaderTable:
+  Sections:
+    - Name: .gnu.version_r
+    - Name: .strtab
+    - Name: .shstrtab
+  Excluded:
+    - Name: .dynstr

llvm/test/tools/yaml2obj/ELF/versym-section.yaml

FileHeader:
   Data:  ELFDATA2LSB
   Type:  ET_EXEC
   Entry: 0x0000000000201000
 Sections:
   - Name:            .gnu.version
     Type:            SHT_GNU_versym
     Flags:           [ SHF_ALLOC ]
     Address:         0x0000000000200210
-    Link:            .dynsym
     AddressAlign:    0x0000000000000002
     EntSize:         0x0000000000000002
     Entries:         [ 0, 3, 4 ]
   - Name:            .gnu.version_r
     Type:            SHT_GNU_verneed
     Flags:           [ SHF_ALLOC ]
     Address:         0x0000000000200250
-    Link:            .dynstr
     AddressAlign:    0x0000000000000004
-    Info:            0x0000000000000001
     Dependencies:
       - Version:         1
         File:            dso.so.0
         Entries:
           - Name:            v1
             Hash:            1937
             Flags:           0
             Other:           3
           - Name:            v2
             Hash:            1938
             Flags:           0
             Other:           4
 DynamicSymbols:
   - Name:    f1
     Binding: STB_GLOBAL
   - Name:    f2
     Binding: STB_GLOBAL
 ...
 
 ## Check we are able to set custom sh_entsize field for SHT_GNU_versym section.
+## Check we link the SHT_GNU_versym section to the .dynsym section by default.
 
 # RUN: yaml2obj --docnum=2 %s -o %t2
-# RUN: llvm-readelf -S %t2 | FileCheck %s --check-prefix=ENTSIZE
+# RUN: llvm-readelf -S %t2 | FileCheck %s -DLINK=2 --check-prefix=FIELDS
 
-# ENTSIZE: Section Headers:
-# ENTSIZE:   [Nr] Name         Type   Address          Off    Size   ES
-# ENTSIZE:   [ 1] .gnu.version VERSYM 0000000000000000 000040 000000 03
+# FIELDS: Section Headers:
+# FIELDS:   [Nr] Name         Type   Address          Off    Size   ES Flg Lk
+# FIELDS:   [ 1] .gnu.version VERSYM 0000000000000000 000040 000000 03     [[LINK]]
+# FIELDS:   [ 2] .dynsym      DYNSYM 0000000000000000 000040 000018 18   A 3
 
 --- !ELF
 FileHeader:
   Class: ELFCLASS64
   Data:  ELFDATA2LSB
   OSABI: ELFOSABI_FREEBSD
   Type:  ET_DYN
 Sections:
   - Name:    .gnu.version
     Type:    SHT_GNU_versym
     EntSize: 0x0000000000000003
     Entries: [ ]
+    Link:    [[LINK=<none>]]
+## Needed to emit the .dynsym section.
+DynamicSymbols: []
+
+## Check we are able to set the sh_link field to an arbitrary value.
+
+# RUN: yaml2obj --docnum=2 -DLINK=0xff %s -o %t2.link
+# RUN: llvm-readelf -S %t2.link | FileCheck %s -DLINK=255 --check-prefix=FIELDS
 
 ## Check we can use the "Content" key with the "Size" key when the size is greater
 ## than or equal to the content size.
+## Also, check that we set the sh_link field to 0 when there is no .dynsym section.
 
 # RUN: not yaml2obj --docnum=3 -DSIZE=1 -DCONTENT="'0011'" %s 2>&1 | \
 # RUN:   FileCheck %s --check-prefix=CONTENT-SIZE-ERR
 
 # CONTENT-SIZE-ERR: error: Section size must be greater than or equal to the content size
 
 --- !ELF
 FileHeader:

 # RUN: yaml2obj --docnum=3 -DSIZE=2 -DCONTENT="'0011'" %s -o %t.cont.size.eq.o
 # RUN: llvm-readobj --sections --section-data %t.cont.size.eq.o | \
 # RUN:   FileCheck %s --check-prefix=CHECK-CONTENT -DDATA="0011"
 
 # RUN: yaml2obj --docnum=3 -DSIZE=3 -DCONTENT="'0011'" %s -o %t.cont.size.gr.o
 # RUN: llvm-readobj --sections --section-data %t.cont.size.gr.o | \
 # RUN:   FileCheck %s --check-prefix=CHECK-CONTENT -DDATA="001100"
 
-# CHECK-CONTENT:      Name: .gnu.version
-# CHECK-CONTENT:      SectionData (
+# CHECK-CONTENT:        Name: .gnu.version
+# CHECK-CONTENT-NEXT:   Type: SHT_GNU_versym (0x6FFFFFFF)
+# CHECK-CONTENT-NEXT:   Flags [ (0x0)
+# CHECK-CONTENT-NEXT:   ]
+# CHECK-CONTENT-NEXT:   Address:
+# CHECK-CONTENT-NEXT:   Offset:
+# CHECK-CONTENT-NEXT:   Size:
+# CHECK-CONTENT-NEXT:   Link: 0
+# CHECK-CONTENT:        SectionData (
 # CHECK-CONTENT-NEXT:   0000: [[DATA]] |
 # CHECK-CONTENT-NEXT: )
 
 ## Check we can use the "Size" key alone to create the section.
 
 # RUN: yaml2obj --docnum=3 -DSIZE=3 %s -o %t.size.o
 # RUN: llvm-readobj --sections --section-data %t.size.o | \
 # RUN:   FileCheck %s --check-prefix=CHECK-CONTENT -DDATA="000000"
 
 ## Check we can use the "Content" key alone to create the section.
 
 # RUN: yaml2obj --docnum=3 -DCONTENT="'112233'" %s -o %t.content.o
 # RUN: llvm-readobj --sections --section-data %t.content.o | \
 # RUN:   FileCheck %s --check-prefix=CHECK-CONTENT -DDATA="112233"
 
 ## Check we can't use the "Entries" key together with the "Content" or "Size" keys.
 
 # RUN: not yaml2obj --docnum=3 -DSIZE=0 -DENTRIES="[]" %s 2>&1 | \
 # RUN:   FileCheck %s --check-prefix=ENTRIES-ERR
 # RUN: not yaml2obj --docnum=3 -DCONTENT="'00'" -DENTRIES="[]" %s 2>&1 | \
 # RUN:   FileCheck %s --check-prefix=ENTRIES-ERR
 
 # ENTRIES-ERR: error: "Entries" cannot be used with "Content" or "Size"
+
+## Check we set the sh_link field to 0 when the .dynsym section is excluded
+## from the section header table.
+
+# RUN: yaml2obj --docnum=4 %s -o %t4
+# RUN: llvm-readelf --sections %t4 | FileCheck %s --check-prefix=EXCLUDED
+
+# EXCLUDED: [Nr] Name         {{.*}} ES Flg Lk Inf
+# EXCLUDED: [ 1] .gnu.version {{.*}} 02     0   0
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_DYN
+Sections:
+  - Name: .gnu.version
+    Type: SHT_GNU_versym
+  - Name: .dynsym
+    Type: SHT_DYNSYM
+SectionHeaderTable:
+  Sections:
+    - Name: .gnu.version
+    - Name: .strtab
+    - Name: .shstrtab
+  Excluded:
+    - Name: .dynsym

llvm/tools/obj2yaml/elf2yaml.cpp

 
 template <class ELFT>
 Expected<ELFYAML::VerdefSection *>
 ELFDumper<ELFT>::dumpVerdefSection(const Elf_Shdr *Shdr) {
   auto S = std::make_unique<ELFYAML::VerdefSection>();
   if (Error E = dumpCommonSection(Shdr, *S))
     return std::move(E);
 
-  S->Info = Shdr->sh_info;
-
   auto StringTableShdrOrErr = Obj.getSection(Shdr->sh_link);
   if (!StringTableShdrOrErr)
     return StringTableShdrOrErr.takeError();
 
   auto StringTableOrErr = Obj.getStringTable(**StringTableShdrOrErr);
   if (!StringTableOrErr)
     return StringTableOrErr.takeError();
 
while (BufAux) {
           StringTableOrErr->drop_front(Verdaux->vda_name).data());
       BufAux = Verdaux->vda_next ? BufAux + Verdaux->vda_next : nullptr;
     }
 
     S->Entries->push_back(Entry);
     Buf = Verdef->vd_next ? Buf + Verdef->vd_next : nullptr;
   }
 
+  if (Shdr->sh_info != S->Entries->size())
+    S->Info = (llvm::yaml::Hex64)Shdr->sh_info;
+
   return S.release();
 }
 
 template <class ELFT>
 Expected<ELFYAML::SymverSection *>
 ELFDumper<ELFT>::dumpSymverSection(const Elf_Shdr *Shdr) {
   auto S = std::make_unique<ELFYAML::SymverSection>();
   if (Error E = dumpCommonSection(Shdr, *S))

 
 template <class ELFT>
 Expected<ELFYAML::VerneedSection *>
 ELFDumper<ELFT>::dumpVerneedSection(const Elf_Shdr *Shdr) {
   auto S = std::make_unique<ELFYAML::VerneedSection>();
   if (Error E = dumpCommonSection(Shdr, *S))
     return std::move(E);
 
-  S->Info = Shdr->sh_info;
-
   auto Contents = Obj.getSectionContents(*Shdr);
   if (!Contents)
     return Contents.takeError();
 
   auto StringTableShdrOrErr = Obj.getSection(Shdr->sh_link);
   if (!StringTableShdrOrErr)
     return StringTableShdrOrErr.takeError();
 
while (BufAux) {
       Entry.AuxV.push_back(Aux);
       BufAux = Vernaux->vna_next ? BufAux + Vernaux->vna_next : nullptr;
     }
 
     S->VerneedV->push_back(Entry);
     Buf = Verneed->vn_next ? Buf + Verneed->vn_next : nullptr;
   }
 
+  if (Shdr->sh_info != S->VerneedV->size())
+    S->Info = (llvm::yaml::Hex64)Shdr->sh_info;
+
   return S.release();
 }
 
 template <class ELFT>
 Expected<StringRef> ELFDumper<ELFT>::getSymbolName(uint32_t SymtabNdx,
                                                    uint32_t SymbolNdx) {
   auto SymtabOrErr = Obj.getSection(SymtabNdx);
   if (!SymtabOrErr)