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From: John Baldwin <jhb@freebsd.org>
To: David Chisnall <theraven@freebsd.org>
Subject: Re: svn commit: r253802 - head/contrib/llvm/tools/clang/lib/Headers
Date: Wed, 14 Aug 2013 08:21:50 -0400
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 (bigwig.baldwin.cx); Wed, 14 Aug 2013 09:57:26 -0400 (EDT)
Cc: Matthew Fleming <mdf@freebsd.org>,
 "src-committers@FreeBSD.org" <src-committers@freebsd.org>,
 Jilles Tjoelker <jilles@stack.nl>,
 "svn-src-all@FreeBSD.org" <svn-src-all@freebsd.org>,
 Dimitry Andric <dim@freebsd.org>,
 "svn-src-head@FreeBSD.org" <svn-src-head@freebsd.org>
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On Wednesday, August 14, 2013 4:23:11 am David Chisnall wrote:
> On 13 Aug 2013, at 21:57, Jilles Tjoelker <jilles@stack.nl> wrote:
> 
> > Given that JIT is for performance and larger addresses increase code
> > size and register pressure, the mmap() flag is probably useful.
> > Alternatively, all the JITted code could be placed in one block and use
> > relative addressing.
> 
> This would be a good thing to have in for 10.0, as the LLVM 3.4 JIT will
> require it unless someone wants to contribute support for the large code
> model...

So you just need a flag to cap the virtual address at 2GB?  Do you think we
need an arbitrary address flag for this, or is a hardcoded 2GB flag ok?

Linux has a MAP_32BIT that does what you want I think.

-- 
John Baldwin