Re: JIT compiling with LLVM v10.0

On Wednesday, February 7, 2018 3:54:05 PM CET Andres Freund wrote:
> Hi,
> 
> I've pushed v10.0. The big (and pretty painful to make) change is that
> now all the LLVM specific code lives in src/backend/jit/llvm, which is
> built as a shared library which is loaded on demand.
> 
> The layout is now as follows:
> 
> src/backend/jit/jit.c:
>     Part of JITing always linked into the server. Supports loading the
>     LLVM using JIT library.
> 
> src/backend/jit/llvm/
> Infrastructure:
>  llvmjit.c:
>     General code generation and optimization infrastructure
>  llvmjit_error.cpp, llvmjit_wrap.cpp:
>     Error / backward compat wrappers
>  llvmjit_inline.cpp:
>     Cross module inlining support
> Code-Gen:
>   llvmjit_expr.c
>     Expression compilation
>   llvmjit_deform.c
>     Deform compilation
> 
> I generally like how this shaped out. There's a good amount of followup
> cleanup needed, but I'd appreciate some early feedback.

Hi

I also find it more readable and it looks cleaner, insane guys could be able 
to write their own JIT engines for PostgreSQL by patching a single file :) 
Since it's now in its own .so file, does it still make as much sense using 
mostly the LLVM C API ?
I'll really look in the jit code itself later, right now I've just rebased my 
previous patches and did a quick check that everything worked for LLVM4 and 
3.9.
I included a small addition to the gitignore file, I'm surprised you were not 
bothered by the various .bc files generated.

Anyway, great work, and I look forward exploring the code :)

 Pierre