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Re: Should we compile Guile with -fno-strict-aliasing?
From: |
Andy Wingo |
Subject: |
Re: Should we compile Guile with -fno-strict-aliasing? |
Date: |
Sun, 29 Jan 2012 22:02:48 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) |
Hi!
On Fri 27 Jan 2012 20:02, Mark H Weaver <address@hidden> writes:
> For many years, Linux (the kernel) has used the -fno-strict-aliasing
> compiler option to disable certain tricky optimizations that depend upon
> a very strict reading of the aliasing rules of modern C standards. It
> turns out that it's quite difficult to write robust code in the presence
> of those optimizations. I have not researched this issue carefully, but
> it seems that several Guile bugs may be related to this problem.
>
> Perhaps we should simply add this compiler flag where its available, at
> least in the short term. What do you think?
So, we added it, for GCC; cool. I was wondering though whether we might
be able to get by with something more limited, at least on GCC. Have
you looked at __attribute__((__may_alias__))? It does seem like a good
idea to add it to SCM, as we frequently alias SCM and scm_t_bits values
at the very least. Also adding it to struct scm_vm_frame would also fix
the vm frame issue.
Dunno. WDYT?
Regards,
Andy
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