[llvm-dev] RFC: Generic IR reductions

[Renato Golin via llvm-dev]

On 1 February 2017 at 14:36, Amara Emerson <amara.emerson at gmail.com> wrote:
> I think you mean take a single vector operand, not two vector
> operands. If the intrinsic took two vectors then we would naturally
> expect the result to be a vector, where each element is the result of
> a scalar operation between each respective element in the vector
> operands. Just like  a normal binary operator.

Precisely.

 %vec = @llvm.maxnum(<N x float> %a, <N x float> %b)
 %scalar = @llvm.maxnum(<N x floag> %c)

In NEON, the former is a simple VMAX (VADD, etc), while the latter can
be a combination of VPMAX (VPADD etc).

cheers,
--renato