[llvm] [SelectionDAG] Fold VECREDUCE_MUL of a constant BUILD_VECTOR (PR #210126)

[Ankit Kumar Tiwari via llvm-commits]

================

----------------
ankit-cybertron wrote:

I see a pattern here if the element count is a power of 2 collapses to something trivial else non-power-of-2 count produces real, unfolded codegen 

https://github.com/llvm/llvm-project/pull/210126