fn shuffleVectorIndex(comptime this_index: c_int, comptime source_vector_len: usize) i32

Convert from clang __builtin_shufflevector index to Zig @shuffle index clang requires __builtin_shufflevector index arguments to be integer constants. negative values for this_index indicate “don’t care” so we arbitrarily choose 0 clang enforces that this_index is less than the total number of vector elements See https://ziglang.org/documentation/master/#shuffle See https://clang.llvm.org/docs/LanguageExtensions.html#langext-builtin-shufflevector

Parameters

this_index: c_int,
source_vector_len: usize,