[llvm] [RISCV] Use LMUL=1 for vmv_s_x_vl with non-undef passthru (PR #66659)

[Luke Lau via llvm-commits]

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@@ -550,9 +550,9 @@ define void @insertelt_c6_v8i64_0_add(ptr %x, ptr %y) {
 ; CHECK-NEXT:    vsetivli zero, 8, e64, m4, ta, ma
 ; CHECK-NEXT:    vle64.v v8, (a0)
 ; CHECK-NEXT:    li a2, 6
-; CHECK-NEXT:    vsetvli zero, zero, e64, m4, tu, ma
+; CHECK-NEXT:    vsetivli zero, 8, e64, m1, tu, ma
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lukel97 wrote:

Did a bit of digging, InsertVSETVLI has to set VL again because VLMAX has changed with LMUL. Allowing the m4 to slide over the vmv.s.x sounds like a good path to take here

https://github.com/llvm/llvm-project/pull/66659