[llvm] [LV] Use wide lane masks as the canonical form when tail-folding & interleaving (PR #209484)

[David Sherwood via llvm-commits]

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@@ -42,30 +42,31 @@ define void @test_uniform(ptr noalias %dst, ptr readonly %src, i64 %uniform , i6
 ; INTERLEAVE-NEXT:    [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
 ; INTERLEAVE-NEXT:    [[TMP1:%.*]] = shl nuw i64 [[TMP0]], 1
 ; INTERLEAVE-NEXT:    [[TMP2:%.*]] = shl nuw i64 [[TMP1]], 1
-; INTERLEAVE-NEXT:    [[ACTIVE_LANE_MASK_ENTRY:%.*]] = call <vscale x 2 x i1> @llvm.get.active.lane.mask.nxv2i1.i64(i64 0, i64 [[N]])
-; INTERLEAVE-NEXT:    [[ACTIVE_LANE_MASK_ENTRY1:%.*]] = call <vscale x 2 x i1> @llvm.get.active.lane.mask.nxv2i1.i64(i64 [[TMP1]], i64 [[N]])
+; INTERLEAVE-NEXT:    [[ACTIVE_LANE_MASK_ENTRY:%.*]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i64(i64 0, i64 [[N]])
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david-arm wrote:

It would be good to let the loop vectoriser explicitly choose better variable names here. For example, something like

```
  %wide_active_lane_mask_entry = call ...
  %active_lane_mask_entry = call <vscale x 2 x i1> @llvm.vector.extract
  %active_lane_mask_entry1 = call <vscale x 2 x i1> @llvm.vector.extract
```

It looked a bit nicer previously when the phi input values were %active_lane_mask_entry, etc.

https://github.com/llvm/llvm-project/pull/209484