[llvm] [RISCV] Merge shuffle sources if lanes are disjoint (PR #119401)

[Philip Reames via llvm-commits]

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@@ -104,60 +104,73 @@ define <512 x i8> @two_source(<512 x i8> %a, <512 x i8> %b) {
 ; CHECK-NEXT:    addi s0, sp, 1536
 ; CHECK-NEXT:    .cfi_def_cfa s0, 0
 ; CHECK-NEXT:    andi sp, sp, -512
-; CHECK-NEXT:    vsetivli zero, 1, e8, m1, ta, ma
-; CHECK-NEXT:    vmv8r.v v24, v8
+; CHECK-NEXT:    vsetivli zero, 8, e64, m1, ta, ma
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preames wrote:

I think this particularly test case is intended to hit the generic fallback.  Can you commit a test change such that the indices aren't disjoint and then rebase?

https://github.com/llvm/llvm-project/pull/119401