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Re: [PATCH] gas/arm: Misses deprecated IT instruction warning for ARMv8
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Nicholas Clifton <nickc at redhat dot com>
- Cc: Jiong Wang <Jiong dot Wang at arm dot com>, "binutils at sourceware dot org" <binutils at sourceware dot org>
- Date: Mon, 16 Jun 2014 15:41:31 +0100
- Subject: Re: [PATCH] gas/arm: Misses deprecated IT instruction warning for ARMv8
- Authentication-results: sourceware.org; auth=none
- References: <539090BE dot 6050906 at arm dot com> <539B1EE2 dot 1090406 at redhat dot com>
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.
R.