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Re: [lto] set alias info, poorly
- From: "Richard Guenther" <richard dot guenther at gmail dot com>
- To: gcc-patches at gcc dot gnu dot org, zadeck at naturalbridge dot com
- Date: Fri, 7 Dec 2007 11:47:46 +0100
- Subject: Re: [lto] set alias info, poorly
- References: <20071206222919.GS14706@codesourcery.com>
On Dec 6, 2007 11:29 PM, Nathan Froyd <froydnj@codesourcery.com> wrote:
> First, the good news about this patch: it fixes a few failing testcases.
>
> The bad news is that it does it with a very heavy hammer. We say that
> every type can alias every other type. Obviously this wreaks havoc with
> all the clever alias analysis that has gone into GCC over the years.
>
> There are better, cleverer, more involved ways that you could fix this.
> But this demonstrably works right now. Ideas on what to do in the
> future welcome.
I believe we have to write out the alias sets and the conflict map and at the
point we combine types of different translation units we have to merge the
alias sets and conflict maps properly.
Or not rely on TBAA for LTO, which is what your patch does (so I guess for
completeness you should disable strict aliasing as well).
Richard.