llvm dev - Jul 2019 - Looking for an out-of-source "Hello, world" LLVM/Clang pass example

Florian,

On 7/10/19 2:17 PM, Florian Hahn wrote:
> http://www.cs.cornell.edu/~asampson/blog/llvm.html describes how to
> create an out-of-source pass (see 'Let’s Write a Pass’). I think it
> is for LLVM 3.8 though.
Thanks for pointing that out.  I had actually recently stumbled across
that page (and the GitHub repository it references,
https://github.com/sampsyo/llvm-pass-skeleton) while searching for an
answer to my questions but wasn't sure how up-to-date the information
is:

  * Is add_library the currently recommended CMake macro call for
    building an LLVM pass?
    http://llvm.org/docs/WritingAnLLVMPass.html and
    https://llvm.org/docs/CMake.html both point to add_llvm_library,
    which I couldn't get to work.

  * Is the legacy pass manager still the right way to make a pass
    Clang-callable?  There's a currently active thread on this list,
    "Status of the New Pass Manager", that makes me think I have some
    code-rewriting in my future.

-- Scott

Scott,

This is still very early stages, but you can be my guinea pig:

https://github.com/banach-space/llvm-tutor

It's a tutorial that I've been preparing recently and am hoping to
present somewhere at some point :-) I believe that it already covers 1),
2) and 3). I haven't had the time to work on 4). It's based on LLVM-8
and includes a working CI set-up, so that you can be confident that it
works. If it doesn't, ping me - I'm keen on improving it.

-- Andrzej

On 11/07/2019 00:54, Scott Pakin via llvm-dev wrote:
> Florian,
>
> On 7/10/19 2:17 PM, Florian Hahn wrote:
>> http://www.cs.cornell.edu/~asampson/blog/llvm.html describes how to
>> create an out-of-source pass (see 'Let’s Write a Pass’). I think it
>> is for LLVM 3.8 though.
>
> Thanks for pointing that out.  I had actually recently stumbled across
> that page (and the GitHub repository it references,
> https://github.com/sampsyo/llvm-pass-skeleton) while searching for an
> answer to my questions but wasn't sure how up-to-date the information
> is:
>
>    * Is add_library the currently recommended CMake macro call for
>      building an LLVM pass?
>      http://llvm.org/docs/WritingAnLLVMPass.html and
>      https://llvm.org/docs/CMake.html both point to add_llvm_library,
>      which I couldn't get to work.
>
>    * Is the legacy pass manager still the right way to make a pass
>      Clang-callable?  There's a currently active thread on this list,
>      "Status of the New Pass Manager", that makes me think I have
some
>      code-rewriting in my future.
>
> -- Scott
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Andrzej,

On 7/14/19 8:02 AM, Andrzej Warzynski wrote:
> This is still very early stages, but you can be my guinea pig:
>
> https://github.com/banach-space/llvm-tutor
>
> It's a tutorial that I've been preparing recently and am hoping to
> present somewhere at some point :-) I believe that it already covers 1),
> 2) and 3). I haven't had the time to work on 4). It's based on
LLVM-8
> and includes a working CI set-up, so that you can be confident that it
> works. If it doesn't, ping me - I'm keen on improving it.
Cool, thanks.  I just started reading over that now.  I have a couple
of questions already, if you don't mind:

1) I see you're building the pass with

    add_library(lt-cc-static STATIC StaticCallCounter.cpp
DynamicCallCounter.cpp)
    add_library(lt-cc-shared MODULE StaticCallCounter.cpp
DynamicCallCounter.cpp)

  What's the reason for building a STATIC version?  Does any LLVM tool
  make use of that?

  Is add_library the preferred pass-building CMake macro these days,
  as opposed to add_llvm_library or add_llvm_loadable_module?

2) How is the user supposed to install the generated files?  Neither
   "make install" nor "cmake --target=install" seem to work.

-- Scott