Re: meson vs. llvm bitcode files

Hi,

On Thu, 5 Sept 2024 at 12:24, Nazir Bilal Yavuz <byavuz81@gmail.com> wrote:
>
> I found that Andres shared a patch
> (v17-0021-meson-Add-LLVM-bitcode-emission.patch) a while ago [1].

Andres and I continued to work on that. I think the patches are in
sharable state now and I wanted to hear opinions before proceeding
further. After applying the patches, bitcode files should be installed
into $pkglibdir/bitcode/ directory if the llvm is found.

There are 6 patches attached:

v1-0001-meson-Add-generated-header-stamps:

This patch is trivial. Instead of having targets depending directly on
the generated headers, have them depend on a stamp file. The benefit
of using a stamp file is that it makes ninja.build smaller and meson
setup faster.
----------

v1-0002-meson-Add-postgresql-extension.pc-for-building-extension-libraries:

This patch is for generating postgresql-extension.pc file which can be
used for building extensions libraries.

Normally, there is no need to use this .pc file for generating bitcode
files. However, since there is no clear way to get all include paths
for building bitcode files, this .pc file is later used for this
purpose (by running pkg-config --cflags-only-I
postgresql-extension-uninstalled.pc) [1].
----------

v1-0003-meson-Test-building-extensions-by-using-postgresql-extension.pc:
[Not needed for generating bitcode files]

This is a patch for testing if extensions can be built by using
postgresql-extension.pc. I added that commit as an example of using
postgresql-extension.pc to build extensions.
----------

v1-0004-meson-WIP-Add-docs-for-postgresql-extension.pc: [Not needed
for generating bitcode files]

I added this patch in case we recommend people to use
postgresql-extension.pc to build extension libraries. I am not sure if
we want to do that because there are still TODOs about
postgresql-extension.pc like running test suites. I just wanted to
show my plan, dividing 'Extension Building Infrastructure' into two,
'PGXS' and 'postgresql-extension.pc'.
----------

v1-0005-meson-Add-LLVM-bitcode-emission:

This patch adds required infrastructure to generate bitcode files and
uses postgresql-extension-uninstalled.pc to get include paths for
generating bitcode files [1].
----------

v1-0006-meson-Generate-bitcode-files-of-contrib-extension.patch:

This patch adds manually selected contrib libraries to generate their
bitcode files. These libraries are selected manually, depending on
- If they have SQL callable functions
- If the library functions are short enough (the performance gain from
bitcode files is too minimal compared to the function's run time, so
this type of libraries are omitted).

Any kind of feedback would be appreciated.

--
Regards,
Nazir Bilal Yavuz
Microsoft