tree 05d5f1a04dbb51d3fd9775187e91f0e2602a211c
parent 16826bfa6f73e938d9f4e01c94af1f8d71028efc
author Nicolas Capens <capn@google.com> 1660145691 -0400
committer Nicolas Capens <nicolascapens@google.com> 1660186571 +0000

Support constructing a SIMD constant from a lambda expression

This makes it easier to construct complex SIMD width dependent constant
vectors. The lambda expression takes the lane index as input and must
return the value for that lane.

Example usage:

SIMD::Int([](int i) { return 1 << i; })

Produces {1, 2, 4, 8, 16, 32, ...}.

Note we also still support construction from an std::vector<>. This is
more verbose as it requires creating a temporary and explicitly looping
for SIMD::Width iterations, but may be easier to read in some cases. It
also supports shorter input vectors, by implicitly applying a modulo
operation, which this new lambda approach does not. So they both have
their uses.

Bug: b/214583550
Change-Id: Ib0b2024cf57254bfa9cc7836ef656f2f507fe21a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/67429
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>