Re: WIP: Faster Expression Processing and Tuple Deforming (including JIT)

From: Nico Williams <nico(at)cryptonector(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Doug Doole <ddoole(at)salesforce(dot)com>
Subject: Re: WIP: Faster Expression Processing and Tuple Deforming (including JIT)
Date: 2016-12-06 21:22:54
Message-ID: 20161206212253.GE32541@localhost
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On Tue, Dec 06, 2016 at 12:36:41PM -0800, Andres Freund wrote:
> On 2016-12-06 15:25:44 -0500, Tom Lane wrote:
> > I'm not entirely thrilled with the idea of this being a configure-time
> > decision, because that forces packagers to decide for their entire
> > audience whether it's okay to depend on LLVM. That would be an untenable
> > position to put e.g. Red Hat's packagers in: either they screw the people
> > who want performance or they screw the people who want security.

There's no security issue. The dependency is on LLVM libraries, not
LLVM front-ends (e.g., clang(1)).

I don't think there's a real issue as to distros/packagers/OS vendors.
They already have to package LLVM, and they already package LLVM
libraries separately from LLVM front-ends.

> The argument for not install a c compiler seems to be that it makes it
> less convenient to build an executable. I doubt that having a C(++)
> library for code generation is convenient enough to change the picture
> there.

The security argument goes back to the days of the Morris worm, which
depended on having developer tools (specifically in that case, ld(1),
the link-editor). But JIT via LLVM won't give hackers a way to generate
or link arbitrary object code.

Nico
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