[PATCH] D77346: [docs] Corrected inaccuracies in Common Problems section

Fri Apr 10 15:37:18 PDT 2020

Meinersbur added inline comments.

================
Comment at: llvm/docs/GettingStarted.rst:1156
+   generate the debug information in the form of a DWARF object file (with the 
+   extension .dwo). This option is only available on Linux.

----------------
aprantl wrote:
> aprantl wrote:
> > Meinersbur wrote:
> > > e-leclercq wrote:
> > > > Meinersbur wrote:
> > > > > I am not sure this is Linux-only. It certainly requires DWARF debug information (.i.e no Windows PDB), but It will probably work on BSDs and maybe also using the target `x86_64-w64-mingw32`.
> > > > I read up on this a bit more and it appears that this works on both UNIX and Linux, so I will definitely change that. I am not quite sure about Windows though, as I came across [[ https://www.phoronix.com/scan.php?page=news_item&px=LLVM-LLDB-Debugger-For-Windows | this article ]]. Would changing this to "This option can be used on both UNIX and Linux" be adequate?
> > > Since the implementation is:
> > > ```
> > > if (LLVM_USE_SPLIT_DWARF AND
> > >     ((uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG") OR
> > >      (uppercase_CMAKE_BUILD_TYPE STREQUAL "RELWITHDEBINFO")))
> > >   # Limit to clang and gcc so far. Add compilers supporting this option.
> > >   if (CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR
> > >       CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
> > >     add_compile_options(-gsplit-dwarf)
> > >   endif()
> > > endif()
> > > ```
> > > AFAIK gcc only supports DWARF. Clang supports split-dwarf for ELF targets.
> > > 
> > > I'd make it a note saying that the option may not be supported on all platforms. On Windows the platform-standard is codeview (`.pdb`) which is always a separate file. I don't know about MacOS.
> > Split DWARF is a DWARF+ELF thing, but not tied to an OS. It's specifically not needed/useful/available for Mach-O (Darwin) because debug info isn't processed by Mach-O linkers at all (instead there is dsymutil).
> > ` This option may not be supported on all platforms.`
> 
> Why be so vague, if we know the answer? Can we just say that this only applies to ELF (e.g, Linux) host platforms?
My thinking was that beginners may not necessarily know what ELF is. But clarifying in parens is a good idea.

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https://reviews.llvm.org/D77346