[llvm-dev] RFC: Complex in LLVM

[Finkel, Hal J. via llvm-dev]

On 7/3/19 2:01 PM, David Greene wrote:
> Tim Northover via llvm-dev <llvm-dev at lists.llvm.org> writes:
>
>> On Tue, 2 Jul 2019 at 19:11, Finkel, Hal J. <hfinkel at anl.gov> wrote:
>>> One option is to make the complex type a special kind of vector, or a
>>> special kind of aggregate (I have a slight preference for the latter).
>>> That gives us an existing set of accessors.
>> I agree non-vector. If nothing else a vector of complexes seems like a
>> sensible concept which would be harder if a complex was itself
>> vectorial.
>>
>> Myself, I think I do favour insertvalue/extractvalue over intrinsics
>> (which is probably a +1 for isAggregate too by extension).
>>
>> If the notation for the literal is especially re/im rather than 0/1 we
>> might think about adding "extractvalue %v, real" as sugar (that last
>> arg is already weird). All just things to think about right now
>> though.
> Great ideas.  Are there downsides to making complex a subclass of an
> aggregate?  I am thinking mainly WRT vectorization.  Does the vectorizer
> expect elements to be scalar/non-aggregate types?


I expect that there are minor changes that would be needed in a bunch of 
different places, but I suspect no worse than adding a novel type. For 
example, VectorType::isValidElementType needs to be updated regardless.

  -Hal


>
>                           -David

-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory