[yaml2obj/obj2yaml] - Make RawContentSection::Info Optional<>

This allows to customize this field for "implicit" sections properly.

Differential revision: https://reviews.llvm.org/D63487

llvm-svn: 363777

llvm/include/llvm/ObjectYAML/ELFYAML.h

@@ -153,7 +153,7 @@ struct DynamicSection : Section {
 struct RawContentSection : Section {
   Optional<yaml::BinaryRef> Content;
   Optional<llvm::yaml::Hex64> Size;
-  llvm::yaml::Hex64 Info;
+  Optional<llvm::yaml::Hex64> Info;
 
   RawContentSection() : Section(SectionKind::RawContent) {}
 

llvm/lib/ObjectYAML/ELFYAML.cpp

@@ -917,7 +917,7 @@ static void sectionMapping(IO &IO, ELFYAML::RawContentSection &Section) {
   commonSectionMapping(IO, Section);
   IO.mapOptional("Content", Section.Content);
   IO.mapOptional("Size", Section.Size);
-  IO.mapOptional("Info", Section.Info, Hex64(0));
+  IO.mapOptional("Info", Section.Info);
 }
 
 static void sectionMapping(IO &IO, ELFYAML::NoBitsSection &Section) {

llvm/test/tools/obj2yaml/sections-info.yaml

@@ -0,0 +1,25 @@
+## Check that obj2yaml does not write a section Info
+## field in the case when it has a value of zero.
+
+# RUN: yaml2obj %s -o %t
+# RUN: obj2yaml %t | FileCheck %s
+
+# CHECK:      Sections:
+# CHECK-NEXT:  - Name: .foo
+# CHECK-NEXT:    Type: SHT_PROGBITS
+# CHECK-NEXT:  - Name: .bar
+# CHECK-NEXT:    Type: SHT_PROGBITS
+# CHECK-NEXT:    Info: 0x0000000000000001
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name: .foo
+    Type: SHT_PROGBITS
+  - Name: .bar
+    Type: SHT_PROGBITS
+    Info: 1

llvm/test/tools/yaml2obj/dynsymtab-implicit-sections-size-content.yaml

@@ -78,7 +78,7 @@ DynamicSymbols:
 # CASE4-NEXT: Offset: 0x180
 # CASE4-NEXT: Size: 2
 # CASE4-NEXT: Link: 0
-# CASE4-NEXT: Info: 0
+# CASE4-NEXT: Info: 1
 # CASE4-NEXT: AddressAlignment: 0
 # CASE4-NEXT: EntrySize: 24
 # CASE4-NEXT: SectionData (
@@ -110,7 +110,7 @@ Sections:
 # CASE5-NEXT: Offset: 0x180
 # CASE5-NEXT: Size: 5
 # CASE5-NEXT: Link: 0
-# CASE5-NEXT: Info: 0
+# CASE5-NEXT: Info: 1
 # CASE5-NEXT: AddressAlignment: 0
 # CASE5-NEXT: EntrySize: 24
 # CASE5-NEXT: SectionData (
@@ -144,7 +144,7 @@ Sections:
 # CASE6-NEXT: Offset: 0x180
 # CASE6-NEXT: Size: 4
 # CASE6-NEXT: Link: 0
-# CASE6-NEXT: Info: 0
+# CASE6-NEXT: Info: 1
 # CASE6-NEXT: AddressAlignment: 0
 # CASE6-NEXT: EntrySize: 24
 # CASE6-NEXT: SectionData (
@@ -178,7 +178,7 @@ Sections:
 # CASE7-NEXT:  Offset: 0x180
 # CASE7-NEXT:  Size: 2
 # CASE7-NEXT:  Link: 0
-# CASE7-NEXT:  Info: 0
+# CASE7-NEXT:  Info: 1
 # CASE7-NEXT:  AddressAlignment: 0
 # CASE7-NEXT:  EntrySize: 24
 # CASE7-NEXT:  SectionData (

llvm/test/tools/yaml2obj/implicit-sections-info.yaml

@@ -0,0 +1,113 @@
+## Check the values of sh_info fields set by default for
+## explicitly listed .dynstr, .dynsym, .strtab and .symtab
+## sections.
+##
+## For symbol table sections, sh_info has a value which is
+## one greater than the symbol table index of the last
+## local symbol.
+##
+## sh_info isn't set for string table sections.
+
+# RUN: yaml2obj --docnum=1 %s -o %t
+# RUN: llvm-readobj --sections %t | FileCheck %s --check-prefix=CASE1
+
+# CASE1:      Name: .symtab
+# CASE1:      Info:
+# CASE1-SAME: 2
+# CASE1:      Name: .strtab
+# CASE1:      Info:
+# CASE1-SAME: 0
+# CASE1:      Name: .dynsym
+# CASE1:      Info:
+# CASE1-SAME: 1
+# CASE1:      Name: .dynstr
+# CASE1:      Info:
+# CASE1-SAME: 0
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:  .symtab
+    Type:  SHT_SYMTAB
+  - Name:  .strtab
+    Type:  SHT_STRTAB
+  - Name:  .dynsym
+    Type:  SHT_DYNSYM
+  - Name:  .dynstr
+    Type:  SHT_STRTAB
+Symbols:
+  - Name:    local
+  - Name:    global1
+    Binding: STB_GLOBAL
+DynamicSymbols:
+  - Name:    global2
+    Binding: STB_GLOBAL
+
+## In the case when these sections are not defined in YAML, the
+## behavior is the same as when we define them, but do not set the Info.
+
+# RUN: yaml2obj --docnum=2 %s -o %t
+# RUN: llvm-readobj --sections %t | FileCheck %s --check-prefix=CASE1
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Symbols:
+  - Name:    local
+  - Name:    global1
+    Binding: STB_GLOBAL
+DynamicSymbols:
+  - Name:    global2
+    Binding: STB_GLOBAL
+
+## Check we are able to set any sh_info explicitly.
+
+# RUN: yaml2obj --docnum=3 %s -o %t
+# RUN: llvm-readobj --sections %t | FileCheck %s --check-prefix=CASE2
+
+# CASE2:      Name: .dynstr
+# CASE2:      Info:
+# CASE2-SAME: 10
+# CASE2:      Name: .dynsym
+# CASE2:      Info:
+# CASE2-SAME: 11
+# CASE2:      Name: .strtab
+# CASE2:      Info:
+# CASE2-SAME: 12
+# CASE2:      Name: .symtab
+# CASE2:      Info:
+# CASE2-SAME: 13
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:  .dynstr
+    Type:  SHT_STRTAB
+    Info:  10
+  - Name:  .dynsym
+    Type:  SHT_DYNSYM
+    Info:  11
+  - Name:  .strtab
+    Type:  SHT_STRTAB
+    Info:  12
+  - Name:  .symtab
+    Type:  SHT_SYMTAB
+    Info:  13
+Symbols:
+  - Name:    local
+  - Name:    global1
+    Binding: STB_GLOBAL
+DynamicSymbols:
+  - Name:    global2
+    Binding: STB_GLOBAL

llvm/test/tools/yaml2obj/symtab-implicit-sections-size-content.yaml

@@ -73,7 +73,7 @@ Symbols:
 # CASE4-NEXT: Offset: 0x140
 # CASE4-NEXT: Size: 2
 # CASE4-NEXT: Link: 2
-# CASE4-NEXT: Info: 0
+# CASE4-NEXT: Info: 1
 # CASE4-NEXT: AddressAlignment: 0
 # CASE4-NEXT: EntrySize: 24
 # CASE4-NEXT: SectionData (
@@ -104,7 +104,7 @@ Sections:
 # CASE5-NEXT: Offset: 0x140
 # CASE5-NEXT: Size: 5
 # CASE5-NEXT: Link: 2
-# CASE5-NEXT: Info: 0
+# CASE5-NEXT: Info: 1
 # CASE5-NEXT: AddressAlignment: 0
 # CASE5-NEXT: EntrySize: 24
 # CASE5-NEXT: SectionData (
@@ -137,7 +137,7 @@ Sections:
 # CASE6-NEXT: Offset: 0x140
 # CASE6-NEXT: Size: 4
 # CASE6-NEXT: Link: 2
-# CASE6-NEXT: Info: 0
+# CASE6-NEXT: Info: 1
 # CASE6-NEXT: AddressAlignment: 0
 # CASE6-NEXT: EntrySize: 24
 # CASE6-NEXT: SectionData (
@@ -170,7 +170,7 @@ Sections:
 # CASE7-NEXT:  Offset: 0x140
 # CASE7-NEXT:  Size: 2
 # CASE7-NEXT:  Link: 2
-# CASE7-NEXT:  Info: 0
+# CASE7-NEXT:  Info: 1
 # CASE7-NEXT:  AddressAlignment: 0
 # CASE7-NEXT:  EntrySize: 24
 # CASE7-NEXT:  SectionData (

llvm/tools/obj2yaml/elf2yaml.cpp

@@ -442,7 +442,8 @@ ELFDumper<ELFT>::dumpContentSection(const Elf_Shdr *Shdr) {
   ArrayRef<uint8_t> Content = *ContentOrErr;
   if (!Content.empty())
     S->Content = yaml::BinaryRef(Content);
-  S->Info = Shdr->sh_info;
+  if (Shdr->sh_info)
+    S->Info = static_cast<llvm::yaml::Hex64>(Shdr->sh_info);
   return S.release();
 }
 

llvm/tools/yaml2obj/yaml2elf.cpp

@@ -436,8 +436,8 @@ void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
 
   // If the symbol table section is explicitly described in the YAML
   // then we should set the fields requested.
-  SHeader.sh_info =
-      RawSec ? (unsigned)RawSec->Info : findFirstNonGlobal(Symbols) + 1;
+  SHeader.sh_info = (RawSec && RawSec->Info) ? (unsigned)(*RawSec->Info)
+                                             : findFirstNonGlobal(Symbols) + 1;
   SHeader.sh_entsize = (YAMLSec && YAMLSec->EntSize)
                            ? (uint64_t)(*YAMLSec->EntSize)
                            : sizeof(Elf_Sym);
@@ -488,6 +488,9 @@ void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
   if (YAMLSec && YAMLSec->EntSize)
     SHeader.sh_entsize = *YAMLSec->EntSize;
 
+  if (RawSec && RawSec->Info)
+    SHeader.sh_info = *RawSec->Info;
+
   if (YAMLSec && YAMLSec->Flags)
     SHeader.sh_flags = *YAMLSec->Flags;
   else if (Name == ".dynstr")
@@ -624,7 +627,10 @@ bool ELFState<ELFT>::writeSectionContent(
     SHeader.sh_entsize = sizeof(Elf_Relr);
   else
     SHeader.sh_entsize = 0;
-  SHeader.sh_info = Section.Info;
+
+  if (Section.Info)
+    SHeader.sh_info = *Section.Info;
+
   return true;
 }