[llvm-readobj] Include section name of notes.

[rupprecht]

Summary

This changes the output of llvm-readelf -n from:

Displaying notes found at file offset 0x<...> with length 0x<...>:

to:

Displaying notes found in: .note.foo

And similarly, adds a Name: field to the llvm-readobj -n output for notes.

This change not only increases GNU compatibility, it also makes it much easier to read notes. Note that we still fall back to printing the file offset/length in cases where we don't have a section name, such as when printing notes in program headers or printing notes in a partially stripped file (GNU readelf does the same).

Fixes llvm.org/PR41339.

[MaskRay]

llvm/test/tools/llvm-readobj/ELF/gnu-notes.test

66

Worth a comment that it has no name.

79

This will be the remaining test for the Displaying notes found at file offset ... form.

Worth a comment that it has no name.

[rupprecht]

• Update test comments

[rupprecht]

Upload correct patch

[grimar]

llvm/tools/llvm-readobj/ELFDumper.cpp

5134 ↗

(On Diff #248370)

Probably,

/*SecName=*/None

6278 ↗

(On Diff #248370)

Should we always print fields? (i.e. print Name=something for !SecName).
Is it the only case for LLVM output where we can omit/print field I guess?
(I remember we had something like this before somewhere and removed it).

[rupprecht]

• Annotate SecName param
• Use <?> for unknown section names

[rupprecht]

llvm/tools/llvm-readobj/ELFDumper.cpp

6278 ↗

(On Diff #248370)

Yes, we do have a custom of printing <?> for unknown sections/symbols. Updated here, but not for GNU output format, for better compatibility.

llvm/test/tools/llvm-readobj/ELF/gnu-notes.test

 # LLVM-NEXT:       Owner: GNU
 # LLVM-NEXT:       Data size: 0x9
 # LLVM-NEXT:       Type: NT_GNU_GOLD_VERSION (gold version)
 # LLVM-NEXT:       Version: gold 1.11
 # LLVM-NEXT:     }
 # LLVM-NEXT:   }
 # LLVM-NEXT: ]
 
-## Note: there is no "Name: .note.gnu.build-id" assertion here because it is stripped.
+## Note: there is no "Name: .note.gnu.build-id" assertion here because the
+## section header table is not present.
 # LLVM-STRIPPED:      Notes [
 # LLVM-STRIPPED-NEXT:   NoteSection {
 # LLVM-STRIPPED-NEXT:     Offset: 0x78
 # LLVM-STRIPPED-NEXT:     Size: 0x20
 # LLVM-STRIPPED-NEXT:     Note {
 # LLVM-STRIPPED-NEXT:       Owner: GNU
 # LLVM-STRIPPED-NEXT:       Data size: 0x10
 # LLVM-STRIPPED-NEXT:       Type: NT_GNU_BUILD_ID (unique build ID bitstring)
 # LLVM-STRIPPED-NEXT:       Build ID: 4fcb712aa6387724a9f465a32cd8c14b
 # LLVM-STRIPPED-NEXT:     }
 # LLVM-STRIPPED-NEXT:   }
 # LLVM-STRIPPED-NEXT: ]
 
-## Note: offset and length printed instead of "found in: .note.gnu.build-id" because it is stripped.
+## Note: offset and length printed instead of "found in: .note.gnu.build-id"
+## because the section header table is not present.
 #      GNU-STRIPPED:Displaying notes found at file offset 0x00000078 with length 0x00000020:
 # GNU-STRIPPED-NEXT:  Owner                Data size  Description
 # GNU-STRIPPED-NEXT:  GNU                  0x00000010 NT_GNU_BUILD_ID (unique build ID bitstring)
 # GNU-STRIPPED-NEXT:    Build ID: 4fcb712aa6387724a9f465a32cd8c14b
 
 --- !ELF
 FileHeader:
   Class:   ELFCLASS64
   Data:    ELFDATA2LSB