[LLVMdev] PR400 - alignment for LD/ST

Christopher Lamb christopher.lamb at gmail.com
Thu Mar 29 14:42:13 PDT 2007

On Mar 29, 2007, at 3:54 PM, Devang Patel wrote:

> Christopher,
> On Mar 29, 2007, at 12:49 PM, Devang Patel wrote:
>> On Mar 29, 2007, at 12:24 PM, Christopher Lamb wrote:
>>> Is anyone actively working on this currently? It's marked as
>>> unassigned in BZ.
>> In next few days I'll get to this. At the moment I'm enabling Packed
>> Structure support in llvm-gcc (based on patches developed by other
>> llvm developers) and adding support for packed bit fields. As part of
>> this work,  alignment for LD/ST is required to access packed  
>> structure
>> fields which are not aligned naturally.
> I get many distractions per day, so do not hesitate if you want to
> take care of PR 400 now.

I'm not really sure exactly what's left to do to fully implement what  
I need. I had assumed that this work would allow me to determine if a  
LD/ST was based on an aligned pointer or not, but this seems now like  
the tip of the iceberg.

I'm hoping that I can declare aligned types and retain that  
information when I pass a pointer to one of these types to function,  
or declare a pointer to an aligned type as a local variable. It seems  
that implementing this not only requires the alignment attribute on  
loads and stores (in the LLVM bc) but propagation of this information  
from the frontend.

Is this correct?

Christopher Lamb
christopher.lamb at gmail.com

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