[LLVMdev] SelectionDAG scalarizes vector operations.

Chris Lattner clattner at apple.com
Wed Feb 8 11:29:33 PST 2012

On Feb 8, 2012, at 9:01 AM, David A. Greene wrote:
> "Rotem, Nadav" <nadav.rotem at intel.com> writes:
>> Hi David!
>> I'd be interested in hearing about the places that you had to fix.  It
>> seems like there is a number of people who are starting to look at the
>> quality of the generated vector code.  Maybe we should report our
>> findings in bug reports, so that we could share the work and discuss
>> possible findings.  I also plan to fill a few bug reports with
>> suboptimal code.
> That's a good idea.  I confess that I don't have a laundry list at-hand.
> These were fixes I made two years ago.  I'll have to do a giant diff
> against the upstream LLVM.  :)
> But yes, I fully intend to send these fixes up.

Would it make sense to start something like a lib/Target/README-Vectors.txt file with a collection of small examples of pessimizations?  We've successfully used text files like this to track "laundry lists" like this.  High priority problems (e.g. the sorts that Duncan is pointing out) makes sense to track in bugzilla, of course.


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