[LLVMdev] stack alignment restriction

[Bill Wendling]

On Dec 29, 2010, at 9:46 AM, drizzle drizzle wrote:

> Thanks for the answer..
> A followup question - Is this already taken into consideration when
> generating address calculation offset etc or would this need to be
> specially taken care?

I believe it should be.

-bw

> I am assuming all load/stores also would need to be custom lowered.
> 
> thanks
> dz
> 
> On Wed, Dec 29, 2010 at 5:45 AM, Bill Wendling <wendling at apple.com> wrote:
>> On Dec 28, 2010, at 4:02 PM, drizzle drizzle wrote:
>> 
>>> Hi
>>>   Is there a way to enforce a different alignment on vales on stack
>>> as compared to other basic types.  Particularly, i would like
>>> characters to be stored at 2 byte boundary.
>>> 
>> Check out examples in the lib/Target/* directories. For instance in X86CallingConv.td, we have things like this:
>> 
>> def CC_X86_64_C : CallingConv<[
>> ...
>>  // __m64 vectors get 8-byte stack slots that are 8-byte aligned.
>>  CCIfType<[x86mmx,v1i64], CCAssignToStack<8, 8>>
>> }
>> 
>> The second parameter to CCAssigneToStack is the alignment for that type.
>> 
>> -bw
>> 
>>