[LLVMdev] [llvm-commits] Major regressions

Christopher Lamb christopher.lamb at gmail.com
Sat Apr 21 21:33:39 PDT 2007

On Apr 21, 2007, at 6:41 PM, Reid Spencer wrote:

> On Sat, 2007-04-21 at 18:28 -0500, Christopher Lamb wrote:
>> On Apr 21, 2007, at 6:12 PM, Reid Spencer wrote:
>>> On Sat, 2007-04-21 at 18:07 -0500, Christopher Lamb wrote:
>>>> I'm getting a regression after my fixes that's coming from
>>>> getABIAlignment not finding an alignment to use for a <float x1>
>>>> type,
>>>> is this a bug?
>>> It could be. <float x 1> isn't a useful vector so it probably  
>>> doesn't
>>> have an ABI Alignment. It should, however, default to whatever the
>>> target's alignment is for float. Perhaps that case isn't covered in
>>> TargetData or there's something else wrong with TargetData?
>>> Did you walk through it in the debugger?
>> Yes. It appears that TargetData doesn't have logic to match the case
>> of vector types smaller than the smallest defined ABI vector type.
>> It's asserting in TargetData::getAlignmentInfo:
>> assert(BestMatchIdx != -1 && "Didn't find alignment info for this
>> datatype!");
> That makes sense.
>> I don't think it has enough information to be able to determine
>> whether or not it's being asked for the alignment of a smaller vector
>> type that could be mapped onto a non-vector type.
> What is your datalayout specification?

It's MacOS X's data layout:
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32- 

>> My feeling is that in this case getAlignmentInfo should return a
>> conservative fallback alignment the same way that's done for  
>> integers.
> Perhaps, we'll need to discuss with Duncan and Chris though.

That's fine. I've split my patch into parts that should be able to be  
applied independently. Only the second part depends on this getting  

Christopher Lamb

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