[cfe-commits] NEON vector alignment
Sandeep Patel
deeppatel1987 at gmail.com
Mon Apr 4 15:28:12 PDT 2011
On Mon, Apr 4, 2011 at 9:18 PM, Bob Wilson <bob.wilson at apple.com> wrote:
>
> On Apr 4, 2011, at 2:12 PM, Sandeep Patel wrote:
>
>> On Mon, Apr 4, 2011 at 4:58 PM, Bob Wilson <bob.wilson at apple.com> wrote:
>>>
>>> On Mar 31, 2011, at 2:06 PM, Sandeep Patel wrote:
>>>
>>>> Clang aligns NEON vectors differently than llvm-gcc does.
>>>>
>>>> llvm-gcc actually calls into ARMTargetMachine to get the layout, but
>>>> Clang provides it's own definitions.
>>>>
>>>> llvm-gcc's definition appears to be correct, so this changes Clang to that.
>>>
>>> Thanks, Sandeep. While reviewing your patch, I noticed that further changes were needed for the APCS ABI, so I went ahead and made those changes as well. Committed as svn r128825.
>>>
>>
>> Now that you made me look at the parts beyond v128 :-), I'm doubting
>> the AACPS values for i1,i8, and i16.
>>
>> The layouts in ARMTargetMachine.cpp for ARM don't have these smaller
>> integer types listed at all. Should they be explicit?
>
> I think it's OK. The ThumbTargetMachine versions have the small integer types listed explicitly because they increase the preferred alignment. I assume there's a good reason for that, but I don't know what it is.
If Thumb had different alignments from ARM, it would be worth a
comment, right? Since there isn't one, that makes me think it's just a
mistake.
(digs through revision history) Looks like r33722 is the reason.
deep
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