[ObjectYAML][ELF] Add support for emitting the .debug_pubnames section.

[Higuoxing]

Summary

This patch helps add support for emitting the .debug_pubnames section to yaml2elf.

Known issues:

• Current implementation doesn't support emitting multiple sets of entries.
• Doesn't support DWARF64.

[jhenderson]

This patch LGTM. Don't spend hours of time working on supporting .pubnames/.pubtypes however, as they aren't widely used by my understanding. Still, for completeness, it doesn't hurt to support them for now.

[Higuoxing]

In D82296#2106599, @jhenderson wrote:

This patch LGTM. Don't spend hours of time working on supporting .pubnames/.pubtypes however, as they aren't widely used by my understanding. Still, for completeness, it doesn't hurt to support them for now.

Yeah, I will not spend too much time on them. In the next patch, I will replace the InitialLength with Format and Length just as what we do in other sections. As for supporting multiple sets of entries, if nobody requests it, I will not work on it.

[jhenderson]

In D82296#2108025, @Higuoxing wrote:

In D82296#2106599, @jhenderson wrote:

This patch LGTM. Don't spend hours of time working on supporting .pubnames/.pubtypes however, as they aren't widely used by my understanding. Still, for completeness, it doesn't hurt to support them for now.

Yeah, I will not spend too much time on them. In the next patch, I will replace the InitialLength with Format and Length just as what we do in other sections. As for supporting multiple sets of entries, if nobody requests it, I will not work on it.

I think if you end up with some spare time towards the end of the project, it doesn't hurt to "finish this off". Just not at the cost of more useful features. I do agree with the Length change though. Consistency is quite important.

[aprantl]

llvm/lib/ObjectYAML/ELFEmitter.cpp

947

FYI: This looks like a good candidate for http://llvm.org/doxygen/classllvm_1_1StringSwitch.html

[Higuoxing]

llvm/lib/ObjectYAML/ELFEmitter.cpp

947

Thanks a lot for pointing this out! I'll look into it.

llvm/lib/ObjectYAML/DWARFYAML.cpp

SetVector<StringRef> DWARFYAML::Data::getUsedSectionNames() const {
   if (!DebugLines.empty())
     SecNames.insert("debug_line");
   if (!DebugAddr.empty())
     SecNames.insert("debug_addr");
   if (!AbbrevDecls.empty())
     SecNames.insert("debug_abbrev");
   if (!CompileUnits.empty())
     SecNames.insert("debug_info");
+  if (PubNames)
+    SecNames.insert("debug_pubnames");
   return SecNames;
 }
 
 namespace yaml {
 
 void MappingTraits<DWARFYAML::Data>::mapping(IO &IO, DWARFYAML::Data &DWARF) {
   auto oldContext = IO.getContext();
   IO.setContext(&DWARF);

llvm/lib/ObjectYAML/ELFEmitter.cpp

Expected<uint64_t> emitDWARF(typename ELFT::Shdr &SHeader, StringRef Name,
   else if (Name == ".debug_line")
     Err = DWARFYAML::emitDebugLine(*OS, DWARF);
   else if (Name == ".debug_addr")
     Err = DWARFYAML::emitDebugAddr(*OS, DWARF);
   else if (Name == ".debug_abbrev")
     Err = DWARFYAML::emitDebugAbbrev(*OS, DWARF);
   else if (Name == ".debug_info")
     Err = DWARFYAML::emitDebugInfo(*OS, DWARF);
+  else if (Name == ".debug_pubnames")
+    Err = DWARFYAML::emitPubSection(*OS, *DWARF.PubNames, DWARF.IsLittleEndian);
   else
     llvm_unreachable("unexpected emitDWARF() call");
 
   if (Err)
     return std::move(Err);
 
   return CBA.tell() - BeginOffset;
 }

llvm/test/tools/yaml2obj/ELF/DWARF/debug-pubnames.yaml

+## Test that yaml2obj emits .debug_pubnames section.
+
+## a) Generate the '.debug_pubnames' section from the 'DWARF' entry.
+
+## Generate and verify a 32-bit little endian .debug_pubnames section.
+
+# RUN: yaml2obj --docnum=1 -DENDIAN=ELFDATA2LSB %s -o %t1.le.o
+# RUN: llvm-readobj --sections --section-data %t1.le.o | \
+# RUN:   FileCheck -DSIZE=30 -DADDRALIGN=1 %s --check-prefixes=SHDR,DWARF32-LE
+
+#            SHDR: Index: 1
+#       SHDR-NEXT: Name: .debug_pubnames (1)
+#       SHDR-NEXT: Type: SHT_PROGBITS (0x1)
+#       SHDR-NEXT: Flags [ (0x0)
+#       SHDR-NEXT: ]
+#       SHDR-NEXT: Address: 0x0
+#       SHDR-NEXT: Offset: 0x40
+#       SHDR-NEXT: Size: [[SIZE]]
+#       SHDR-NEXT: Link: 0
+#       SHDR-NEXT: Info: 0
+#       SHDR-NEXT: AddressAlignment: [[ADDRALIGN]]
+#       SHDR-NEXT: EntrySize: 0
+# DWARF32-LE-NEXT: SectionData (
+# DWARF32-LE-NEXT:   0000: 34120000 02003412 00002143 00007856 |4.....4...!C..xV|
+##                         ^-------                            unit_length (4-byte)
+##                                  ^---                       version (2-byte)
+##                                      ^--------              debug_info_offset (4-byte)
+##                                               ^--------     debug_info_length (4-byte)
+##                                                        ^--- offset (4-byte)
+##
+# DWARF32-LE-NEXT:   0010: 34126162 63002143 65876465 6600     |4.abc.!Ce.def.|
+##                         ----
+##                             ^--------                       name "abc\0"
+##                                      ^--------              offset (4-byte)
+##                                               ^--------     name "def\0"
+# DWARF32-LE-NEXT: )
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    [[ENDIAN]]
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+DWARF:
+  debug_pubnames:
+    Length:
+      TotalLength: 0x1234
+    Version:    2
+    UnitOffset: 0x1234
+    UnitSize:   0x4321
+    Entries:
+      - DieOffset: 0x12345678
+        Name:      abc
+      - DieOffset: 0x87654321
+        Name:      def
+
+## Generate and verify a 32-bit big endian .debug_pubnames section.
+
+# RUN: yaml2obj --docnum=1 -DENDIAN=ELFDATA2MSB %s -o %t1.be.o
+# RUN: llvm-readobj --sections --section-data %t1.be.o | \
+# RUN:   FileCheck -DSIZE=30 -DADDRALIGN=1 %s --check-prefixes=SHDR,DWARF32-BE
+
+# DWARF32-BE-NEXT: SectionData (
+# DWARF32-BE-NEXT:   0000: 00001234 00020000 12340000 43211234 |...4.....4..C!.4|
+##                         ^-------                            unit_length (4-byte)
+##                                  ^---                       version (2-byte)
+##                                      ^--------              debug_info_offset (4-byte)
+##                                               ^--------     debug_info_length (4-byte)
+##                                                        ^--- offset (4-byte)
+##
+# DWARF32-BE-NEXT:   0010: 56786162 63008765 43216465 6600     |Vxabc..eC!def.|
+##                         ----
+##                             ^--------                       name "abc\0"
+##                                      ^--------              offset (4-byte)
+##                                               ^--------     name "def\0"
+# DWARF32-BE-NEXT: )
+
+## b) Generate the .debug_pubnames section from raw section content.
+
+# RUN: yaml2obj --docnum=2 %s -o %t2.o
+# RUN: llvm-readobj --sections --section-data %t2.o | \
+# RUN:   FileCheck %s -DADDRALIGN=0 -DSIZE=3 --check-prefixes=SHDR,ARBITRARY-CONTENT
+
+#      ARBITRARY-CONTENT: SectionData (
+# ARBITRARY-CONTENT-NEXT:   0000: 112233
+# ARBITRARY-CONTENT-NEXT: )
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+Sections:
+  - Name:    .debug_pubnames
+    Type:    SHT_PROGBITS
+    Content: "112233"
+
+## c) Generate the .debug_pubnames section when the "Size" is specified.
+
+# RUN: yaml2obj --docnum=3 %s -o %t3.o
+# RUN: llvm-readobj --sections --section-data %t3.o | \
+# RUN:   FileCheck -DSIZE=16 -DADDRALIGN=0 %s --check-prefixes=SHDR,SIZE
+
+#      SIZE: SectionData (
+# SIZE-NEXT:   0000: 00000000 00000000 00000000 00000000  |................|
+# SIZE-NEXT: )
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+Sections:
+  - Name: .debug_pubnames
+    Type: SHT_PROGBITS
+    Size: 0x10
+
+## d) Test that yaml2obj emits an error message when both the "Size" and the
+## "debug_pubnames" entry are specified at the same time.
+
+# RUN: not yaml2obj --docnum=4 %s 2>&1 | FileCheck %s --check-prefix=ERROR
+
+# ERROR: yaml2obj: error: cannot specify section '.debug_pubnames' contents in the 'DWARF' entry and the 'Content' or 'Size' in the 'Sections' entry at the same time
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+Sections:
+  - Name: .debug_pubnames
+    Type: SHT_PROGBITS
+    Size: 0x10
+DWARF:
+  debug_pubnames:
+    Length:
+      TotalLength: 0x1234
+    Version:    2
+    UnitOffset: 0x1234
+    UnitSize:   0x4321
+    Entries:    []
+
+## e) Test that yaml2obj emits an error message when both the "Content" and the
+## "debug_pubnames" entry are specified at the same time.
+
+# RUN: not yaml2obj --docnum=5 %s 2>&1 | FileCheck %s --check-prefix=ERROR
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+Sections:
+  - Name:    .debug_pubnames
+    Type:    SHT_PROGBITS
+    Content: "00"
+DWARF:
+  debug_pubnames:
+    Length:
+      TotalLength: 0x1234
+    Version:    2
+    UnitOffset: 0x1234
+    UnitSize:   0x4321
+    Entries:    []
+
+## f) Test that all the properties can be overridden by the section header when
+## the "debug_pubnames" entry doesn't exist.
+
+# RUN: yaml2obj --docnum=6 %s -o %t6.o
+# RUN: llvm-readelf --sections %t6.o | FileCheck %s --check-prefix=OVERRIDDEN
+
+#      OVERRIDDEN: [Nr] Name            Type   Address          Off    Size   ES Flg Lk Inf Al
+#      OVERRIDDEN: [ 1] .debug_pubnames STRTAB 0000000000002020 000050 00000e 01   A  2   1  2
+# OVERRIDDEN-NEXT: [ 2] .sec            STRTAB 0000000000000000 00005e 000000 00      0   0  0
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+Sections:
+  - Name:         .debug_pubnames
+    Type:         SHT_STRTAB  ## SHT_PROGBITS by default.
+    Flags:        [SHF_ALLOC] ## 0 by default.
+    Link:         .sec        ## 0 by default.
+    EntSize:      1           ## 0 by default.
+    Info:         1           ## 0 by default.
+    AddressAlign: 2           ## 0 by default.
+    Address:      0x2020      ## 0x00 by default.
+    Offset:       0x50        ## 0x40 for the first section.
+    Size:         0x0e        ## Set the "Size" so that we can reuse the check tag "OVERRIDDEN".
+  - Name:         .sec        ## Linked by .debug_pubnames.
+    Type:         SHT_STRTAB
+
+## g) Test that all the properties can be overridden by the section header when
+## the "debug_pubnames" entry exists.
+
+# RUN: yaml2obj --docnum=7 %s -o %t7.o
+# RUN: llvm-readelf --sections %t7.o | FileCheck %s --check-prefix=OVERRIDDEN
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+Sections:
+  - Name:         .debug_pubnames
+    Type:         SHT_STRTAB  ## SHT_PROGBITS by default.
+    Flags:        [SHF_ALLOC] ## 0 by default.
+    Link:         .sec        ## 0 by default.
+    EntSize:      1           ## 0 by default.
+    Info:         1           ## 0 by default.
+    AddressAlign: 2           ## 1 by default.
+    Address:      0x2020      ## 0x00 by default.
+    Offset:       0x50        ## 0x40 for the first section.
+  - Name:         .sec        ## Linked by .debug_pubnames.
+    Type:         SHT_STRTAB
+DWARF:
+  debug_pubnames:
+    Length:
+      TotalLength: 0x1234
+    Version:    2
+    UnitOffset: 0x1234
+    UnitSize:   0x4321
+    Entries:    []