[docs][llvm-readelf] Expand llvm-readelf documentation

[jhenderson]

Summary

Previously, the llvm-readelf documentation was essentially just a list of differences to llvm-readobj. Since llvm-readelf is the more likely goto tool for many people migrating to the LLVM toolchain, it seems like it would be helpful to document all the switches in the llvm-readelf document too. This change expands the options listed accordingly. Additionally, they are unlikely to care what the differences are to llvm-readobj, since they won't be familiar with the latter as there is no GNU equivalent, so this change moves the "differences" section to llvm-readobj's documentation.

[peter.smith]

Overall no objections. Only thing I can think of that could be surprising is the presence of mach-o and coff options in llvm-readelf. A case could be made for leaving these out as people migrating won't need to use them, but I don't have a strong opinion.

[jhenderson]

In D63826#1559403, @peter.smith wrote:

Overall no objections. Only thing I can think of that could be surprising is the presence of mach-o and coff options in llvm-readelf. A case could be made for leaving these out as people migrating won't need to use them, but I don't have a strong opinion.

I'd be okay with this, but in that case, I'd recommend hiding the options in the help text too, so that's possibly tangential to this change? I'll post something on the mailing list to see if anybody else has any thoughts.

[jhenderson]

In D63826#1560291, @jhenderson wrote:

I'll post something on the mailing list to see if anybody else has any thoughts.

Done: http://lists.llvm.org/pipermail/llvm-dev/2019-June/133384.html

[peter.smith]

In D63826#1560462, @jhenderson wrote:

In D63826#1560291, @jhenderson wrote:

I'll post something on the mailing list to see if anybody else has any thoughts.

Done: http://lists.llvm.org/pipermail/llvm-dev/2019-June/133384.html

Thanks. If you don't get any feedback, feel free to choose your own way.

[jhenderson]

Rebase + remove Mach-O and COFF options from the llvm-readelf documentation. I'll upload another review at a later point to remove the same options from llvm-readelf's help text.

[peter.smith]

Thanks for the update. I'm happy with the changes.

[jhenderson]

In D63826#1564599, @peter.smith wrote:

Thanks for the update. I'm happy with the changes.

Thanks. I'm committing this now, but I'm happy for more feedback if people want to give any.

llvm/trunk/docs/CommandGuide/llvm-readelf.rst

+llvm-readelf - GNU-style LLVM Object Reader
+===========================================
+
+.. program:: llvm-readelf
+
+SYNOPSIS
+--------
+
+:program:`llvm-readelf` [*options*] [*input...*]
+
+DESCRIPTION
+-----------
+
+The :program:`llvm-readelf` tool displays low-level format-specific information
+about one or more object files.
+
+If ``input`` is "``-``" or omitted, :program:`llvm-readelf` reads from standard
+input. Otherwise, it will read from the specified ``filenames``.
+
+OPTIONS
+-------
+
+.. option:: --all
+
+ Equivalent to specifying all the main display options.
+
+.. option:: --addrsig
+
+ Display the address-significance table.
+
+.. option:: --arm-attributes
+
+ Display the ARM attributes section. Only applicable for ARM architectures.
+
+.. option:: --color
+
+ Use colors in the output for warnings and errors.
+
+.. option:: --demangle, -C
+
+ Display demangled symbol names in the output.
+
+.. option:: --dyn-relocations
+
+ Display the dynamic relocation entries.
+
+.. option:: --dyn-symbols, --dyn-syms
+
+ Display the dynamic symbol table.
+
+.. option:: --dynamic-table, --dynamic, -d
+
+ Display the dynamic table.
+
+.. option:: --elf-cg-profile
+
+ Display the callgraph profile section.
+
+.. option:: --elf-hash-histogram, --histogram, -I
+
+ Display a bucket list histogram for dynamic symbol hash tables.
+
+.. option:: --elf-linker-options
+
+ Display the linker options section.
+
+.. option:: --elf-output-style=<value>
+
+ Specify the style to dump ELF information in. Valid options are ``LLVM`` and
+ ``GNU``. ``LLVM`` output is an expanded and structured format, whilst ``GNU``
+ (the default) output mimics the equivalent GNU :program:`readelf` output.
+
+.. option:: --elf-section-groups, --section-groups, -g
+
+ Display section groups.
+
+.. option:: --expand-relocs
+
+ When used with :option:`--relocations`, display each relocation in an expanded
+ multi-line format.
+
+.. option:: --file-headers, -h
+
+ Display file headers.
+
+.. option:: --gnu-hash-table
+
+ Display the GNU hash table for dynamic symbols.
+
+.. option:: --hash-symbols
+
+ Display the dynamic symbols derived from the hash table.
+
+.. option:: --hash-table
+
+ Display the hash table for dynamic symbols.
+
+.. option:: --headers, -e
+
+ Equivalent to setting: :option:`--file-headers`, :option:`--program-headers`,
+ and :option:`--sections`.
+
+.. option:: --help
+
+ Display a summary of command line options.
+
+.. option:: --help-list
+
+ Display an uncategorized summary of command line options.
+
+.. option:: --hex-dump=<section[,section,...]>, -x
+
+ Display the specified section(s) as hexadecimal bytes. ``section`` may be a
+ section index or section name.
+
+.. option:: --needed-libs
+
+ Display the needed libraries.
+
+.. option:: --notes, -n
+
+ Display all notes.
+
+.. option:: --program-headers, --segments, -l
+
+ Display the program headers.
+
+.. option:: --raw-relr
+
+ Do not decode relocations in RELR relocation sections when displaying them.
+
+.. option:: --relocations, --relocs, -r
+
+ Display the relocation entries in the file.
+
+.. option:: --sections, --section-headers, -S
+
+ Display all sections.
+
+.. option:: --section-data
+
+ When used with :option:`--sections`, display section data for each section shown.
+
+.. option:: --section-mapping
+
+ Display the section to segment mapping.
+
+.. option:: --section-relocations
+
+ When used with :option:`--sections`, display relocations for each section shown.
+
+.. option:: --section-symbols
+
+ When used with :option:`--sections`, display symbols for each section shown.
+
+.. option:: --stackmap
+
+ Display contents of the stackmap section.
+
+.. option:: --string-dump=<section[,section,...]>, -p
+
+ Display the specified section(s) as a list of strings. ``section`` may be a
+ section index or section name.
+
+.. option:: --symbols, --syms, -s
+
+ Display the symbol table.
+
+.. option:: --unwind, -u
+
+ Display unwind information.
+
+.. option:: --version
+
+ Display the version of this program.
+
+.. option:: --version-info, -V
+
+ Display version sections.
+
+.. option:: @<FILE>
+
+ Read command-line options from response file `<FILE>`.
+
+EXIT STATUS
+-----------
+
+:program:`llvm-readelf` returns 0 under normal operation. It returns a non-zero
+exit code if there were any errors.
+
+SEE ALSO
+--------
+
+:manpage:`llvm-nm(1)`, :manpage:`llvm-objdump(1)`, :manpage:`llvm-readobj(1)`

llvm/trunk/docs/CommandGuide/llvm-readobj.rst

 -----------
 
 The :program:`llvm-readobj` tool displays low-level format-specific information
 about one or more object files.
 
 If ``input`` is "``-``" or omitted, :program:`llvm-readobj` reads from standard
 input. Otherwise, it will read from the specified ``filenames``.
 
+DIFFERENCES TO LLVM-READELF
+---------------------------
+
+:program:`llvm-readelf` is an alias for the :manpage:`llvm-readobj` tool with a
+slightly different command-line interface and output that is GNU compatible.
+Following is a list of differences between :program:`llvm-readelf` and
+:program:`llvm-readobj`:
+
+- :program:`llvm-readelf` uses `GNU` for the :option:`--elf-output-style` option
+  by default. :program:`llvm-readobj` uses `LLVM`.
+- :program:`llvm-readelf` allows single-letter grouped flags (e.g.
+  ``llvm-readelf -SW`` is the same as  ``llvm-readelf -S -W``).
+  :program:`llvm-readobj` does not allow grouping.
+- :program:`llvm-readelf` provides :option:`-s` as an alias for
+  :option:`--symbols`, for GNU :program:`readelf` compatibility, whereas it is
+  an alias for :option:`--section-headers` in :program:`llvm-readobj`.
+- :program:`llvm-readobj` provides ``-t`` as an alias for :option:`--symbols`.
+  :program:`llvm-readelf` does not.
+- :program:`llvm-readobj` provides ``--sr``, ``--sd``, ``--st`` and ``--dt`` as
+  aliases for :option:`--section-relocations`, :option:`--section-data`,
+  :option:`--section-symbols` and :option:`--dyn-symbols` respectively.
+  :program:`llvm-readelf` does not provide these aliases, to avoid conflicting
+  with grouped flags.
+
 GENERAL AND MULTI-FORMAT OPTIONS
 --------------------------------
 
 These options are applicable to more than one file format, or are unrelated to
 file formats.
 
 .. option:: --all