[llvm] [RISCV] Lower fixed reverse vector_shuffles through vector_reverse (PR #104461)

[Philip Reames via llvm-commits]

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@@ -229,10 +229,10 @@ define <32 x i8> @reverse_v32i8(<32 x i8> %a) {
 ; CHECK-LABEL: reverse_v32i8:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    li a0, 32
-; CHECK-NEXT:    lui a1, %hi(.LCPI12_0)
-; CHECK-NEXT:    addi a1, a1, %lo(.LCPI12_0)
 ; CHECK-NEXT:    vsetvli zero, a0, e8, m2, ta, ma
-; CHECK-NEXT:    vle8.v v12, (a1)
+; CHECK-NEXT:    vid.v v10
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preames wrote:

Luke is right.  We do allow a negative step, it's just that the addend is "too large" in this case.  We should probably adjust our generic lowering as emitting the li seems like the right choice here.  

https://github.com/llvm/llvm-project/pull/104461