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Re: ARM: VFPv3-D16 vs. VFPv3-D32
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Sebastian Huber <sebastian dot huber at embedded-brains dot de>
- Cc: Joey Ye <joey dot ye dot cc at gmail dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Thu, 17 Oct 2013 13:48:51 +0100
- Subject: Re: ARM: VFPv3-D16 vs. VFPv3-D32
- Authentication-results: sourceware.org; auth=none
- References: <525F8DFE dot 7050406 at embedded-brains dot de> <CAL0py25cb8Bi0X0QK+g1e4dY-B4orWVodpS1k9-dM5CacYPvOA at mail dot gmail dot com> <525F962E dot 30309 at embedded-brains dot de> <CAL0py26RM_tD2hGv3+6pu_kSizFkbdG=mcfM7wh-0B_y5v5pnQ at mail dot gmail dot com> <525FD6F2 dot 9000809 at arm dot com> <525FDC0A dot 9030801 at embedded-brains dot de>
On 17/10/13 13:46, Sebastian Huber wrote:
> On 2013-10-17 14:24, Richard Earnshaw wrote:
>> On 17/10/13 08:56, Joey Ye wrote:
>>>> There is no macro to indicate VFP variances. Probably you can check
>>>> CPU variance instead. As I know Cortex-R only support D16.
>>>>
>> Checking __ARM_ARCH_PROFILE == 'R' would tell you that it's R profile
>> and therefore only 16 regs.
>
> Thanks for this information. I was not aware that no existing Cortex-R variant
> has a D32 VFP unit.
>
> Is the converse true for Cortex-A variants or are there Cortex-A cores with
> VFP-D16 and VFP-D32 units?
>
No, the converse is not true. In general (though I don't think there's
a guarantee that this will be the case) if you don't have Neon you won't
have D32. However, if you have Neon you must have D32. Not all
Cortex-A cores have Neon; though many do these days.
R.