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Re: [PATCH] Prevent unnecessary recompilation for trivial params.def changes

From: Jeff Law <law at redhat dot com>
To: Tom de Vries <Tom_deVries at mentor dot com>, Andreas Schwab <schwab at suse dot de>
Cc: "gcc-patches at gnu dot org" <gcc-patches at gnu dot org>
Date: Tue, 8 Sep 2015 15:08:18 -0600
Subject: Re: [PATCH] Prevent unnecessary recompilation for trivial params.def changes
Authentication-results: sourceware.org; auth=none
References: <55EEBC91 dot 7060901 at mentor dot com> <mvmtwr5npl1 dot fsf at hawking dot suse dot de> <55EEC58A dot 8060308 at mentor dot com> <mvmpp1tnmnh dot fsf at hawking dot suse dot de> <55EEE0D4 dot 7050900 at mentor dot com>

On 09/08/2015 07:21 AM, Tom de Vries wrote:

[ was: Re: [RFC] Prevent unnecessary recompilation for trivial
params.def changes ]

On 08/09/15 14:03, Andreas Schwab wrote:

Tom de Vries <Tom_deVries@mentor.com> writes:

After a subsequent rebuild I don't see anything being rebuild. So I
don't
observe 'continuous rebuilding'.


What happens when you just touch params-list.h or params.def?
move-if-change will leave the target untouched when unchanged (that's
the whole point of it), so it will remain older than the dependencies.


I could reproduce the problem using these instructions, thanks.

I also found a bit "On the use of stamps" in gcc/Makefile.in, which
explains the problem and how to fix things.

Updated patch accordingly.

OK for trunk if bootstrap succeeds?

Yes.
jeff

Follow-Ups:
- Re: [PATCH] Prevent unnecessary recompilation for trivial params.def changes
  - From: Tom de Vries

References:
- [RFC] Prevent unnecessary recompilation for trivial params.def changes
  - From: Tom de Vries
- Re: [RFC] Prevent unnecessary recompilation for trivial params.def changes
  - From: Andreas Schwab
- Re: [RFC] Prevent unnecessary recompilation for trivial params.def changes
  - From: Tom de Vries
- Re: [RFC] Prevent unnecessary recompilation for trivial params.def changes
  - From: Andreas Schwab
- [PATCH] Prevent unnecessary recompilation for trivial params.def changes
  - From: Tom de Vries

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