Re: JIT compiling with LLVM v11

On Thu, Mar 15, 2018 at 1:20 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> I don't really live in the RHEL world, but I wonder if
> https://developers.redhat.com/blog/2017/10/04/red-hat-adds-go-clangllvm-rust-compiler-toolsets-updates-gcc/
> is relevant?

Indeed. It might be a bit awkward for packagers to depend on something
from Software Collections, for example because they come as separate
trees in /opt that are by default not in your path or dynamic loader
path - one needs to run everything via a scl wrapper or source the
/opt/rh/llvm-toolset-7/enable file to get the appropriate PATH and
LD_LIBRARY_PATH settings, But it seems doable.

I just installed llvm-toolset-7 (the LLVM version is 4.0.1) on RHEL
7.4 and did a build of your tree at
475b4da439ae397345ab3df509e0e8eb26a8ff39. make installcheck passes for
both the default config and a server forced to jit everything (I
think) via:
jit_above_cost = '0'
jit_inline_above_cost = '0'
jit_optimize_above_cost = '0'

As a side note, this increases the runtime from approx 4 min to 18
min. Disabling jit completely with -1 in all of the above yields 3 min
48s, close to the default question raising maybe the question of how
much coverage does jit get with the default config.

The build was with the newer gcc 7.2.1 from the aforementioned
collections, I'll try the system gcc as well. I run a buildfarm animal
(katydid) on this RHEL. When JIT gets committed I'll make it use
--with-llvm against this Software Collections LLVM.

> Appears to be available on centos too
> https://www.softwarecollections.org/en/scls/rhscl/devtoolset-7/

Indeed they are available for CentOS as well.