Placeholder patch for when the reduction intrinsics drop their experimental status, emitting the equivalent reduction intrinsic in IR instead of expanding to shuffle+arithmetic sequences.
The fadd/fmul reductions might be trickier as they assume a similar bisection reduction while the generic intrinsics assume a sequential reduction (intel docs are ambiguous on the correct approach) - I'm not sure if we want to always tag them with reassoc? Anyway, that issue can wait until a separate fp patch along with the fmin/fmax reductions.
clang-tidy: error: "Never use <avx512fintrin.h> directly; include <immintrin.h> instead." [clang-diagnostic-error]
not useful