[llvm] [RISCV][LoopVectorize] Use DataWithEVL as the preferred tail folding style (PR #148686)

[Philip Reames via llvm-commits]

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@@ -133,33 +133,40 @@ define void @trip8_i8(ptr noalias nocapture noundef %dst, ptr noalias nocapture
 ; CHECK-NEXT:    [[TMP4:%.*]] = mul nuw i64 [[TMP3]], 4
 ; CHECK-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; CHECK:       vector.body:
-; CHECK-NEXT:    [[ACTIVE_LANE_MASK:%.*]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i64(i64 0, i64 8)
-; CHECK-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[TMP8:%.*]], i32 0
-; CHECK-NEXT:    [[WIDE_MASKED_LOAD:%.*]] = call <vscale x 4 x i8> @llvm.masked.load.nxv4i8.p0(ptr [[TMP9]], i32 1, <vscale x 4 x i1> [[ACTIVE_LANE_MASK]], <vscale x 4 x i8> poison)
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[EVL_BASED_IV:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_EVL_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[AVL:%.*]] = sub i64 8, [[EVL_BASED_IV]]
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preames wrote:

Note that because the backed is not taken, this should simplify away.  Please confirm that instcombine can do that if the result is run through it.  

https://github.com/llvm/llvm-project/pull/148686