[PATCH] gas/arm: Misses deprecated IT instruction warning for ARMv8

[Jiong Wang]

On 16/06/14 16:31, Jiong Wang wrote:
> On 16/06/14 15:41, Richard Earnshaw wrote:
>> On 13/06/14 16:55, Nicholas Clifton wrote:
>>> Hi Jiong,
>>>
>>>> given code:
>>>>
>>>> .thumb
>>>> .syntax unified
>>>>
>>>> it eq
>>>> addeq sp, sp, #12
>>>>
>>>> assembled with -march=armv8-a -mthumb, gas fails to warn
>>>> that this is a deprecated form.
>>> Where is this deprecation specified ?   Please can you give a reference
>>> so that I can check it ?
>>>
>>> Cheers
>>>      Nick
>>>
>>>
>> It's in section F6.2 of the v8 ARM ARM:
>>
>> Registered users can get a copy from here:
>>
>> http://arminfo.emea.arm.com/help/topic/com.arm.doc.ddi0487a.b/DDI0487A_b_armv8_arm.pdf
>>
>> But this doesn't look right, since the instructions you need to match
>> don't follow this pattern:
>>
>> +  { 0x00dd, 0x7fff, N_("ADD/SUB sp, sp #imm") },
>>
>> Specifically SUB SP is 0b101100001xxxxxxx
>> and ADD SP is 0b101100000xxxxxxx.
>>
>> Iff your mask is right, it needs a comment to explain why.
> yes, the mask confuse people at the first glance.
>
> the reason to put "0x00dd" there is because arm assembler is using the
> pseudo "tvalue" which is from the table "T16_32_TAB", instead of the
> original encoding when that checking happen.
>
> the real encoding will be converted back at later stage in "md_apply_fix".
>
> OK for trunk?

   Sorry, updated the patch, it's better to put the explain as NOTE 
comment in the code.

   Please review.

   Thanks.

>
> Thanks
>
>> R.
>>
>>
>
>
>
>
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