From: Cedric Blancher <cedric.blancher@gmail.com>
To: Matthew Wilcox <mawilcox@linuxonhyperv.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Konstantin Khlebnikov <koct9i@gmail.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Matthew Wilcox <mawilcox@microsoft.com>
Subject: Re: [PATCH 2/2] radix-tree: Fix optimisation problem
Date: Sun, 25 Sep 2016 01:35:27 +0200 [thread overview]
Message-ID: <CALXu0Ucx-6PeEk9nTD-4nZvwyVr9LLXcFGFzhctX-ucKfCygGA@mail.gmail.com> (raw)
In-Reply-To: <1474570415-14938-3-git-send-email-mawilcox@linuxonhyperv.com>
On 22 September 2016 at 20:53, Matthew Wilcox
<mawilcox@linuxonhyperv.com> wrote:
> From: Matthew Wilcox <mawilcox@microsoft.com>
>
> When compiling the radix tree with -O2, GCC thinks it can optimise:
>
> void *entry = parent->slots[offset];
> int siboff = entry - parent->slots;
If entry is a pointer to void, how can you do pointer arithmetic with it?
Also, if you use pointer distances, the use of int is not valid, it
should then be ptrdiff_t siboff.
lint(1) would bite your arse off in both cases.
Sadly only UNIX (Solaris, AIX, ...) use lint(1) as mandatory part of
the build process and make warnings and errors of lint(1) fatal...
Ced
--
Cedric Blancher <cedric.blancher@gmail.com>
[https://plus.google.com/u/0/+CedricBlancher/]
Institute Pasteur
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next prev parent reply other threads:[~2016-09-24 23:35 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-22 18:53 [PATCH 0/2] Fix radix_tree_lookup_slot() Matthew Wilcox
2016-09-22 18:53 ` [PATCH 1/2] radix tree test suite: Test radix_tree_replace_slot() for multiorder entries Matthew Wilcox
2016-09-22 18:53 ` [PATCH 2/2] radix-tree: Fix optimisation problem Matthew Wilcox
2016-09-22 18:09 ` Linus Torvalds
2016-09-23 20:16 ` Matthew Wilcox
2016-09-24 20:21 ` Linus Torvalds
2016-09-24 20:47 ` Linus Torvalds
2016-09-24 21:04 ` Kirill A. Shutemov
2016-09-24 22:54 ` Linus Torvalds
2016-09-26 4:26 ` Ross Zwisler
2016-09-24 8:36 ` Konstantin Khlebnikov
2016-09-24 23:35 ` Cedric Blancher [this message]
2016-09-25 0:18 ` Linus Torvalds
2016-09-25 17:59 ` Cedric Blancher
2016-09-25 18:04 ` Linus Torvalds
2016-09-25 19:04 ` Linus Torvalds
2016-09-25 19:40 ` Cedric Blancher
2016-09-25 19:56 ` Linus Torvalds
2016-09-26 21:28 ` Matthew Wilcox
2016-09-26 21:48 ` Cedric Blancher
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