[llvm-commits] [llvm] r61934 - in /llvm/trunk: lib/Analysis/ValueTracking.cpp test/Transforms/InstCombine/2009-01-08-AlignAlloca.ll

[Chris Lattner]

On Jan 8, 2009, at 2:25 PM, Dan Gohman wrote:

>
> On Jan 8, 2009, at 12:48 PM, Chris Lattner wrote:
>
>> On Jan 8, 2009, at 11:45 AM, Dan Gohman wrote:
>>>> it will just get the ABI alignment.  This prevents instcombine from
>>>> rounding
>>>> up the alignment of a load/store without adjusting the alignment of
>>>> the alloca.
>>>
>>> When would a default-alignment Alloca not be given its preferred
>>> alignment?
>>>
>>> Or, if you prefer that instcombine make give all Allocas an explicit
>>> alignment, could you add a comment to this code?
>>
>> InstCombine already has code to handle this (see
>> EnforceKnownAlignment).  It isn't catching this case, but it could be
>> made to do so if it were important.
>
> Perhaps I was unclear. Is this commit fixing a miscompile?  If so,
> it seems that there's a bug elsewhere.  CodeGen ought to be aligning
> such Allocas at their preferred alignment.

No, this is just something that Evan noticed.  I don't know that it  
actually manifested as a bug.

-Chris