[ObjectYAML][ELF] Let the endianness of DWARF sections be inferred from FileHeader.

[Higuoxing]

Summary

This patch helps infer the endianness of DWARF sections from FileHeader.

[jhenderson]

Same comments generally apply to this test case as the big endian one from D80972. Otherwise, this looks fine.

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

7–9

You're welcome to continue to use %t1.o and %t2.o etc if you want - my previous suggestion in this area was more by way of example. What you have here is fine too though.

[grimar]

This LGTM.

(With @jhenderson comments addressed. Haven't saw them when approved).

[Higuoxing]

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

7–9

%t.be.o and %t.le.o belong to the test case (a). I want to avoid having something like:

# RUN: yaml2obj --docnum=1 %s -o %t1.o ## Big endian case.
...
# RUN: yaml2obj --docnum=1 %s -o %t2.o ## Little endian case.
...
# RUN: yaml2obj --dconum=2 %s -o %t3.o

[Higuoxing]

• Rebase.
• Address comments in D80972.
  • Remove spaces between dashes.

[jhenderson]

LGTM.

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

7–9

Makes sense.

llvm/lib/ObjectYAML/ELFYAML.cpp

void MappingTraits<ELFYAML::Object>::mapping(IO &IO, ELFYAML::Object &Object) {
   IO.mapTag("!ELF", true);
   IO.mapRequired("FileHeader", Object.Header);
   IO.mapOptional("SectionHeaderTable", Object.SectionHeaders);
   IO.mapOptional("ProgramHeaders", Object.ProgramHeaders);
   IO.mapOptional("Sections", Object.Chunks);
   IO.mapOptional("Symbols", Object.Symbols);
   IO.mapOptional("DynamicSymbols", Object.DynamicSymbols);
   IO.mapOptional("DWARF", Object.DWARF);
+  if (Object.DWARF)
+    Object.DWARF->IsLittleEndian =
+        Object.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
   IO.setContext(nullptr);
 }
 
 void MappingTraits<ELFYAML::LinkerOption>::mapping(IO &IO,
                                                    ELFYAML::LinkerOption &Opt) {
   assert(IO.getContext() && "The IO context is not initialized");
   IO.mapRequired("Name", Opt.Key);
   IO.mapRequired("Value", Opt.Value);

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

 ## Test that yaml2obj emits .debug_aranges section.
 
 ## a) Generate the .debug_aranges section from the "DWARF" entry.
 
 ## Generate and verify a big endian object file.
 
-# RUN: yaml2obj --docnum=1 -DENDIAN=ELFDATA2MSB %s -o %t1.o
-# RUN: llvm-readobj --sections --section-data %t1.o | \
+# RUN: yaml2obj --docnum=1 -DENDIAN=ELFDATA2MSB %s -o %t.be.o
+# RUN: llvm-readobj --sections --section-data %t.be.o | \
 # RUN:   FileCheck %s -DADDRALIGN=1 -DSIZE=96 --check-prefixes=DWARF-BE-HEADER,DWARF-BE-CONTENT
 
 #       DWARF-BE-HEADER: Index: 1
 #  DWARF-BE-HEADER-NEXT: Name: .debug_aranges (1)
 #  DWARF-BE-HEADER-NEXT: Type: SHT_PROGBITS (0x1)
 #  DWARF-BE-HEADER-NEXT: Flags [ (0x0)
 #  DWARF-BE-HEADER-NEXT: ]
 #  DWARF-BE-HEADER-NEXT: Address: 0x0
 #  DWARF-BE-HEADER-NEXT: Offset: 0x40
- Length:
       AddrSize: 0x08
       SegSize:  0x00
       Descriptors:
         - Address: 0x0000000000005678
           Length:  0x20
         - Address: 0x0000000056780000
           Length:  0x10
 
+## Generate and verify a little endian object file.
+
+# RUN: yaml2obj --docnum=1 -DENDIAN=ELFDATA2LSB %s -o %t.le.o
+# RUN: llvm-readobj --sections --section-data %t.le.o | \
+# RUN:   FileCheck %s --check-prefixes=DWARF-LE-DEFAULT
+
+#      DWARF-LE-DEFAULT: Section {
+#      DWARF-LE-DEFAULT:   Index: 1
+# DWARF-LE-DEFAULT-NEXT:   Name: .debug_aranges (1)
+# DWARF-LE-DEFAULT-NEXT:   Type: SHT_PROGBITS (0x1)
+# DWARF-LE-DEFAULT-NEXT:   Flags [ (0x0)
+# DWARF-LE-DEFAULT-NEXT:   ]
+# DWARF-LE-DEFAULT-NEXT:   Address: 0x0
+# DWARF-LE-DEFAULT-NEXT:   Offset: 0x40
+# DWARF-LE-DEFAULT-NEXT:   Size: 96
+# DWARF-LE-DEFAULT-NEXT:   Link: 0
+# DWARF-LE-DEFAULT-NEXT:   Info: 0
+# DWARF-LE-DEFAULT-NEXT:   AddressAlignment: 1
+# DWARF-LE-DEFAULT-NEXT:   EntrySize: 0
+# DWARF-LE-DEFAULT-NEXT:   SectionData (
+# DWARF-LE-DEFAULT-NEXT:     0000: 2C000000 02000000 00000400 00000000
+##                                 |        |   |        | |  |
+##                                 |        |   |        | |  +------- Padding zeros (4-byte)
+##                                 |        |   |        | +- SegSize (1-byte) 0x00
+##                                 |        |   |        +- AddrSize (1-byte) 0x04
+##                                 |        |   +-------- CuOffset (4-byte) 0x00
+##                                 |        +--- Version (2-byte) 0x02
+##                                 +------- InitialLength (4-byte) 0x2c
+##
+# DWARF-LE-DEFAULT-NEXT:     0010: 34120000 20000000 00000000 00000000
+##                                 |        |        |
+##                                 |        |        +---------------- Terminating Entry
+##                                 |        +------- Length (4-byte) 0x20
+##                                 +------- Address (4-byte) 0x1234
+##
+# DWARF-LE-DEFAULT-NEXT:     0020: 2C000000 02006500 00000800 00000000
+##                                 |        |   |        | |  |
+##                                 |        |   |        | |  +------- Padding zeros (4-byte)
+##                                 |        |   |        | +- SegSize (1-byte) 0x00
+##                                 |        |   |        +- AddrSize (1-byte) 0x08
+##                                 |        |   +-------- CuOffset (4-byte) 0x00
+##                                 |        +--- Version (2-byte) 0x02
+##                                 +------- InitialLength (4-byte) 0x2c
+##
+# DWARF-LE-DEFAULT-NEXT:     0030: 78560000 00000000 20000000 00000000
+##                                 |                 |
+##                                 |                 +---------------- Length (8-byte) 0x20
+##                                 +---------------- Address (8-byte) 0x5678
+##
+# DWARF-LE-DEFAULT-NEXT:     0040: 00007856 00000000 10000000 00000000
+##                                 |                 |
+##                                 |                 +---------------- Length (8-byte) 0x10
+##                                 +---------------- Address (8-byte) 0x5678
+##                           
+# DWARF-LE-DEFAULT-NEXT:     0050: 00000000 00000000 00000000 00000000
+##                                 |
+##                                 +---------------------------------- Terminating entry
+##
+# DWARF-LE-DEFAULT-NEXT:   )
+# DWARF-LE-DEFAULT-NEXT: }
+
 ## b) Generate the .debug_aranges 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=DWARF-BE-HEADER,ARBITRARY-CONTENT
 
 #      ARBITRARY-CONTENT: SectionData (
 # ARBITRARY-CONTENT-NEXT:   0000: 112233