[llvm] [AArch64] SVE Shuffleopt: merge reduction reverse into tbl (PR #206047)

[Graham Hunter via llvm-commits]

================
@@ -155,10 +155,130 @@ static void evaluateDeinterleave(IntrinsicInst *I, DeinterleaveMap &Candidates,
   Candidates.try_emplace(I, Extends);
 }
 
+/// Evaluate a reverse intrinsic to see what uses it. We want to find a reverse
+/// that pairs with an extract from a deinterleave, so that we can move the
+/// reverse into the tbl as well as deinterleave and extend. We also need to
----------------
huntergr-arm wrote:

This pass currently transforms deinterleave+extend into tbl instructions; this is an additional shuffle we can try to fold in at the same time.

https://github.com/llvm/llvm-project/pull/206047