Re: meson vs. llvm bitcode files

Hello,

I did a full review on the provided patches plus some tests, I was able to
validate that the loading of bitcode modules is working also JIT works for
both backend and contrib modules.

To test JIT on contrib modules I just lowered the costs for all jit
settings and used the intarray extension, using the data/test__int.data:
CREATE EXTENSION intarray;
CREATE TABLE test__int( a int[] );1
\copy test__int from 'data/test__int.data'

For queries any from line 98+ on contrib/intarray/sql/_int.sql will work.

Then I added extra debug messages to llvmjit_inline.cpp
on add_module_to_inline_search_path() function, also
on llvm_build_inline_plan(), I was able to see many functions in this
module being successfully inlined.

I'm attaching a new patch based on your original work which add further
support for generating bitcode from:
- Generated backend sources: processed by flex, bison, etc.
- Generated contrib module sources,

On this patch I just included fmgrtab.c and src/backend/parser for the
backend generated code.
For contrib generated sources I added contrib/cube as an example.

All relevant details about the changes are included in the patch itself.

As you may know already I also created a PR focused on llvm bitcode
emission on meson, it generates bitcode for all backend and contribution
modules, currently under review by some colleagues at Percona:
https://github.com/percona/postgres/pull/103
I'm curious if we should get all or some of the generated backend sources
compiled to bitcode, similar to contrib modules.
Please let me know your thoughts and how we can proceed to get this feature
included, thank you.

Regards,
Diego Fronza
Percona

On Fri, Mar 7, 2025 at 7:52 AM Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com> wrote:

> Hi,
>
> On Thu, 5 Sept 2024 at 12:24, Nazir Bilal Yavuz <byavuz81(at)gmail(dot)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
>