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Re: [PATCH 4/4] Convert lto streamer out hashing to inchash
- From: Andi Kleen <ak at linux dot intel dot com>
- To: Jeff Law <law at redhat dot com>
- Cc: Andi Kleen <andi at firstfloor dot org>, gcc-patches at gcc dot gnu dot org
- Date: Wed, 23 Jul 2014 07:36:23 -0700
- Subject: Re: [PATCH 4/4] Convert lto streamer out hashing to inchash
- Authentication-results: sourceware.org; auth=none
- References: <1405488709-12677-1-git-send-email-andi at firstfloor dot org> <1405488709-12677-2-git-send-email-andi at firstfloor dot org> <1405488709-12677-3-git-send-email-andi at firstfloor dot org> <1405488709-12677-4-git-send-email-andi at firstfloor dot org> <1405488709-12677-5-git-send-email-andi at firstfloor dot org> <53CF2E9F dot 9010103 at redhat dot com>
On Tue, Jul 22, 2014 at 09:40:15PM -0600, Jeff Law wrote:
> On 07/15/14 23:31, Andi Kleen wrote:
> >From: Andi Kleen <firstname.lastname@example.org>
> >No substantial changes, although the hash values will be slightly
> >2014-07-10 Andi Kleen <email@example.com>
> > * lto-streamer-out.c (hash_tree): Convert to inchash.
> > (add_flag): New macro.
> So my question here, does this make any existing LTO objects no longer
> usable? If so, what, if any policy do we have when we make that kind of
It breaks the format because a few type hashes change
But breaks happen all the time during development. Currently just adding
a new command option breaks the format. Or pretty much any change to
Generally in my experience LTO object files don't stay usable more
than a few days in phase 1.
Currently the format is even broken for patch level releases, usually
due to some option change.
The policy is just that for a given release that is unchanged the
object format stays compatible.
I submitted some patches to improve this slightly for the options,
but they were not accepted because of all the other issues.
Given that reality I assume the patch is ok for you?
firstname.lastname@example.org -- Speaking for myself only