[llvm] [RISCV] Reduce LMUL when index is known when lowering insert_vector_elt (PR #66087)

[Luke Lau via llvm-commits]

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@@ -51,22 +51,19 @@ define <vscale x 8 x i32> @insert_nxv8i32_v2i32_6(<vscale x 8 x i32> %vec, ptr %
 define <vscale x 8 x i32> @insert_nxv8i32_v8i32_0(<vscale x 8 x i32> %vec, ptr %svp) {
 ; LMULMAX2-LABEL: insert_nxv8i32_v8i32_0:
 ; LMULMAX2:       # %bb.0:
-; LMULMAX2-NEXT:    vsetivli zero, 8, e32, m2, ta, ma
-; LMULMAX2-NEXT:    vle32.v v12, (a0)
-; LMULMAX2-NEXT:    vsetivli zero, 8, e32, m4, tu, ma
-; LMULMAX2-NEXT:    vmv.v.v v8, v12
+; LMULMAX2-NEXT:    vsetivli zero, 8, e32, m2, tu, ma
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lukel97 wrote:

This is `performCombineVMergeAndVOps` kicking in, https://reviews.llvm.org/D157272 also does this

https://github.com/llvm/llvm-project/pull/66087