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Re: [PATCH] Fix i686 memchr for large input sizes
- From: Siddhesh Poyarekar <siddhesh at gotplt dot org>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>, libc-alpha at sourceware dot org
- Date: Tue, 3 Jan 2017 00:33:09 +0530
- Subject: Re: [PATCH] Fix i686 memchr for large input sizes
- Authentication-results: sourceware.org; auth=none
- References: <1483367199-20720-1-git-send-email-adhemerval.zanella@linaro.org>
On Monday 02 January 2017 07:56 PM, Adhemerval Zanella wrote:
> Similar to BZ#19387 and BZ#20971, both i686 memchr optimized assembly
> implementations (memchr-sse2-bsf and memchr-sse2) do not handle the
> size overflow correctly.
>
> It is shown by the new tests added by commit 3daef2c8ee4df29, where
> both implementation fails with size as SIZE_MAX.
>
> This patch uses a similar strategy used on 3daef2c8ee4df2, where
> saturared math is used for overflow case.
>
> Checked on i686-linux-gnu.
>
> [BZ #21014]
> * sysdeps/i386/i686/multiarch/memchr-sse2-bsf.S (MEMCHR): Avoid overflow
> in pointer addition.
> * sysdeps/i386/i686/multiarch/memchr-sse2.S (MEMCHR): Likewise.
Looks good to me.
Siddhesh