[llvm-commits] [llvm] r46349 - /llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

[Chris Lattner]

On Jan 25, 2008, at 8:37 AM, Duncan Sands wrote:

>>> PS: Does an alignment of 0 mean the ABI alignment or the preferred
>>> alignment?  I'm guessing that it means ABI for globals and
>>> preferred for allocas.
>>
>> In what context?
>
> In any context :)  Basically I'm asking what it means if you pass an
> alignment of 0 for an alloca (or a global).  For example, llvm-gcc
> uses alignment 0 for an alloca if the ABI alignment equals the gcc
> alignment.  But if the alloca gets the preferred alignment in the
> end (at codegen time) and this differs from the ABI alignment, then
> this would be wrong.

It looks like selectiondagisel is using the max(requested alignment,  
preferred alignment) for the type for allocas.  This makes sense.

-Chris