From: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To: Ramsay Jones <ramsay@ramsayjones.plus.com>
Cc: linux-sparse@vger.kernel.org
Subject: Re: [PATCH 2/3] add memory asm constraint for PPC
Date: Sat, 4 Jul 2020 21:32:48 +0200 [thread overview]
Message-ID: <20200704193248.simtaedrt7gbiepy@ltop.local> (raw)
In-Reply-To: <693a3fa0-5202-3695-54cf-aa1cc1f514fd@ramsayjones.plus.com>
On Sat, Jul 04, 2020 at 06:44:53PM +0100, Ramsay Jones wrote:
>
> Hi Luc,
>
> All of the patches in this series look good to me! ;-)
>
> (I have been following all patches on the list, I just
> haven't had anything to say about them - which is a good thing!)
Hi,
Yes, indeed. Thank you!
> On 04/07/2020 14:57, Luc Van Oostenryck wrote:
> > The 'Z' asm constraint is used for doing IO accessors on PPC but
> > isn't part of the 'common constraints'. It's responsible for
> > more than half of all warnings (with defconfig + allyesconfig).
>
> Not a problem, but this made me think 'half of which warnings'. :-D
> I assume, but it's just a guess, this means 'half of all asm-constraints
> warnings on the kernel PPC build'.
>
> How many warnings is that? What percentage is that of _all_ sparse
> warnings on a typical kernel build?
It's literally more than half of all warnings issued by sparse when doing
a build of the kernel with 'defconfig' and another one with 'allyesconfig'
(all my tests on kernel builds are done like so) on a ppc64 machine:
$ grep ': \(error\|warning\):' log-master-master | wc -l
138581
$ grep ': \(error\|warning\):' log-arch-asm-mem | wc -l
50006
So, this series eliminates about 64% of all warnings, a nice
improvement of the S/N ratio.
Now, most of these warnings are exactly the same, again and again:
$ diff -U1 log-master-master log-arch-asm-mem
--- log-master-master 2020-07-04 14:40:56.733110303 +0200
+++ log-arch-asm-mem 2020-07-04 15:46:47.972595182 +0200
@@ -1 +1 @@
-SPARSE=fa1539620
+SPARSE=69fedae3e
@@ -24,8 +23,0 @@
-./arch/powerpc/include/asm/io.h:143:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:144:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:148:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:149:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:143:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:144:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:148:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:149:1: warning: dereference of noderef expression
@@ -41 +32,0 @@
-./arch/powerpc/include/asm/io.h:144:1: warning: dereference of noderef expression
@@ -56,4 +46,0 @@
-./arch/powerpc/include/asm/io.h:143:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:144:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:148:1: warning: dereference of noderef expression
-./arch/powerpc/include/asm/io.h:149:1: warning: dereference of noderef expression
...
If you count only unique warnings, the result is quite different:
@gcc203:~/dev $ grep ': \(error\|warning\):' log-master-master | sort -u | wc -l
19071
@gcc203:~/dev $ grep ': \(error\|warning\):' log-arch-asm-mem | sort -u | wc -l
19067
Only 4 unique warnings are eliminated.
For comparison, on x86_64 the warnings are:
$ grep ': \(error\|warning\):' log-master-master | wc -l
29806
$ grep ': \(error\|warning\):' log-master-master | sort -u | wc -l
19234
> Thanks!
>
> [BTW, I also noticed the (long running) 'luc/options' branch, which
> looks like it could prove to be a nice cleanup - I've only read the
> commit messages, not the actual commits.]
Yes, I think it's a nice cleanup because this code is quite messy but,
OTOH, moving around all this code break all its history (via 'git blame'
or 'git log -L') is is guaranteed to create really nasty conflicts with
anything touching the code for the options. This is really a downside.
Best regards,
-- Luc
next prev parent reply other threads:[~2020-07-04 19:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-04 13:57 [PATCH 0/3] teach sparse about arch specific asm constraints Luc Van Oostenryck
2020-07-04 13:57 ` [PATCH 1/3] add support for " Luc Van Oostenryck
2020-07-04 13:57 ` Luc Van Oostenryck
2020-07-04 13:57 ` [PATCH 2/3] add memory asm constraint for PPC Luc Van Oostenryck
2020-07-04 17:44 ` Ramsay Jones
2020-07-04 19:32 ` Luc Van Oostenryck [this message]
2020-07-04 21:07 ` Ramsay Jones
2020-07-04 22:44 ` Luc Van Oostenryck
2020-07-04 13:57 ` [PATCH 3/3] add memory asm constraint for S390 Luc Van Oostenryck
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