[llvm-dev] Making llvm-xyz -help useful

[Chris Lattner via llvm-dev]

Unrelated to your actual question, but why are we linking targets into llvm-cat?

-Chris

> On May 9, 2019, at 9:23 AM, Serge Guelton via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> Hi folks,
> 
> today, I wanted to concatenate two .ll, and naively typed:
> 
>    $ llvm-cat -help
> 
> This is the not-so-helpful output I had:
> 
>    OVERVIEW: Module concatenation
>    USAGE: llvm-cat [options] <input  files>
> 
>    OPTIONS:
> 
>    General options:
> 
>      -aarch64-neon-syntax                              - Choose style of NEON code to emit from AArch64 backend:
>        =generic                                        -   Emit generic NEON assembly
>        =apple                                          -   Emit Apple-style NEON assembly
>      -amdgpu-dump-hsa-metadata                         - Dump AMDGPU HSA Metadata
>      -amdgpu-enable-merge-m0                           - Merge and hoist M0 initializations
>      -amdgpu-sdwa-peephole                             - Enable SDWA peepholer
>    [...]
> 
> Surely, the style of NEON code to emit from AArch64 backend is not the information I was looking for...
> 
> I've implemented a straight-forward patch for llvm-cat here https://reviews.llvm.org/D61740, and the result becomes:
> 
>    OVERVIEW: Module concatenation
>    USAGE: llvm-cat [options] <input  files>
> 
>    OPTIONS:
> 
>    Generic Options:
> 
>      --help        - Display available options (--help-hidden for more)
>      --help-list   - Display list of available options (--help-list-hidden for more)
>      --version     - Display the version of this program
> 
>    llvm-cat Options:
> 
>      -b            - Whether to perform binary concatenation
>      -o=<filename> - Output filename
> 
> 
> Depending on the tools, the filtering imposed by llvm::cl::HideUnrelatedOptions may be too harsh, but there's still -help-hidden for the curious!
> 
> Any thoughts on that approach? Should I go on that way for other tools? If so, anyone willing to be auto-added as a reviewer?
> 
> ++
> Serge
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