This patch was buried at the end of the discussion...
-- Christopher Lamb Begin forwarded message: Date: April 22, 2007 4:12:29 AM CDT Subject: Re: [llvm-commits] Major regressions
On Apr 22, 2007, at 1:40 AM, Chris Lattner wrote:
On Apr 21, 2007, at 4:28 PM, 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!");
Ahh.
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.
My feeling is that in this case getAlignmentInfo should return a conservative fallback alignment the same way that's done for integers.
I think it should fall back to the ABI alignment of the scalar type. If a target doesn't have an entry for a vector type, we can assume that it will be scalarized.
Here's a patch to do it. -- Christopher Lamb
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degenerate_vectors.diff
Description: Binary data
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