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Re: [PATCH] Remove incorrect register mov in floorf on x86_64
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Siddhesh Poyarekar <siddhesh at redhat dot com>, OndÅej BÃlka <neleai at seznam dot cz>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 14 Aug 2015 16:45:10 -0400
- Subject: Re: [PATCH] Remove incorrect register mov in floorf on x86_64
- Authentication-results: sourceware.org; auth=none
- References: <20150814103330 dot GA15748 at spoyarek dot pnq dot redhat dot com> <20150814111204 dot GA20519 at domone> <20150814111949 dot GK24813 at spoyarek dot pnq dot redhat dot com> <CAMe9rOqzxjfmGg1sJGPUtwmWWN58vQwUw711UfukNcRP_MUAKg at mail dot gmail dot com> <55CE4A20 dot 3060903 at redhat dot com> <CAMe9rOpP6=i9=h+a_qu44=tknisgcA46UiuZ9NYVQH=7ObK3tw at mail dot gmail dot com>
On 08/14/2015 04:36 PM, H.J. Lu wrote:
> On Fri, Aug 14, 2015 at 1:05 PM, Carlos O'Donell <carlos@redhat.com> wrote:
>> On 08/14/2015 08:34 AM, H.J. Lu wrote:
>>> On Fri, Aug 14, 2015 at 4:19 AM, Siddhesh Poyarekar <siddhesh@redhat.com> wrote:
>>>> On Fri, Aug 14, 2015 at 01:12:04PM +0200, OndÅej BÃlka wrote:
>>>>> It isn't incorrect, just dead move. Ok for me.
>>>>
>>>> No, it loads an arbitrary value (we don't know what is in %rax at that
>>>> point) into %rdx and overwrites the struct address.
>>>>
>>>
>>> Thanks for catching it. I checked in your patch together with the same
>>> fix for sysdeps/x86_64/fpu/multiarch/s_nearbyint.S
>>
>> Why didn't testing catch this? Is it because this is a multiarch that
>> didn't get tested?
>
> RAX contains a valid address, but not the correct address. Since
> my machine has SSE4.1, any version works. But machines without
> SSE4.1 may fail.
OK, that's what I figured. I'll see what we can do to make this better.
Cheers,
Carlos.