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Re: [PATCH, i386] Add option to control rounding bits of SAE-only instructions.
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Ilya Tocar <tocarip dot intel at gmail dot com>
- Cc: Binutils <binutils at sourceware dot org>
- Date: Tue, 16 Sep 2014 08:17:19 -0700
- Subject: Re: [PATCH, i386] Add option to control rounding bits of SAE-only instructions.
- Authentication-results: sourceware.org; auth=none
- References: <20140915133351 dot GA1778 at msticlxl7 dot ims dot intel dot com> <CAMe9rOqPgGDOyPUdKbHL71M7uJCqeOMEJn=Ah=LGc9TVCYez7Q at mail dot gmail dot com> <20140916114452 dot GA33334 at msticlxl7 dot ims dot intel dot com>
On Tue, Sep 16, 2014 at 4:44 AM, Ilya Tocar <tocarip.intel@gmail.com> wrote:
> On 15 Sep 09:06, H.J. Lu wrote:
>> On Mon, Sep 15, 2014 at 6:33 AM, Ilya Tocar <tocarip.intel@gmail.com> wrote:
>> > Hi,
>> >
>> > For SAE-only evex instructions rounding/LL bits can have any value.
>> > Currently we encode them with 00 bits. Attached patch add -mevexrndig
>> > option, which controls this behavior.
>> > Ok for trunk?
>>
>> A couple comments:
>>
>> 1. Please use -mevexrcig.
>> 2. Please remove force_rounding_bits and just do
>>
>> else if (evexrcig)
>> i.vex.bytes[3] |= 0x10 | (evexrcig << 5);
>>
>> and make sure there is one space between "0x10 |" and "(evexrcig << 5);".
>> 3. Sync against trunk since I renamed OPTION_omit_lock_prefix
>> to OPTION_OMIT_LOCK_PREFIX.
>
> Done.
Please
1. Change the commit log to
Add -mevexrcig={rne|rd|ru|rz} option to x86 assembler
It is used to control which value is encoded in rounding control bits for
SAE-only EVEX instructions.
...
2. Mention it in md_show_usage.
3. In c-i386.texi, replace "LL bits" with "RC bits".
Thanks.
--
H.J.