[LLVMdev] [llvm-commits] Vectors of Pointers and Vector-GEP

David A. Greene greened at obbligato.org
Mon Dec 5 14:10:07 PST 2011

Jose Fonseca <jfonseca at vmware.com> writes:

> I was referring to gathering a vector of sparse 32bit words, all
> relative from a base scalar pointer in a 64bit address space, where
> the offsets are in a 32bit integer vector.  My other reply gave a more
> detailed and concrete example.

Yep, I saw that.  I think LLVM IR should support it directly.

> Anyway, from Nadav's and your other replies on this thread it is now
> clear to me that even if the IR doesn't express base scalar pointers
> w/ vector indices directly, the backend can always match and emit the
> most efficient machine instruction. This addresses my main concern.

It can, but it would have to go through varying amounts of pain to do
so.  This is such a common operation that the IR should really support
it directly.


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