[llvm] [LoopVectorizer] Allow partial reductions to be made in predicated loops (PR #124268)

[Sam Tebbs via llvm-commits]

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@@ -1596,7 +1596,7 @@ define i32 @not_dotp_predicated_pragma(i64 %N, ptr %a, ptr %b) {
 ; CHECK-INTERLEAVE1:       vector.body:
 ; CHECK-INTERLEAVE1-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[PRED_LOAD_CONTINUE62:%.*]] ]
 ; CHECK-INTERLEAVE1-NEXT:    [[VEC_IND:%.*]] = phi <16 x i64> [ <i64 0, i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7, i64 8, i64 9, i64 10, i64 11, i64 12, i64 13, i64 14, i64 15>, [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[PRED_LOAD_CONTINUE62]] ]
-; CHECK-INTERLEAVE1-NEXT:    [[VEC_PHI:%.*]] = phi <16 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP180:%.*]], [[PRED_LOAD_CONTINUE62]] ]
+; CHECK-INTERLEAVE1-NEXT:    [[VEC_PHI:%.*]] = phi <4 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[PARTIAL_REDUCE:%.*]], [[PRED_LOAD_CONTINUE62]] ]
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SamTebbs33 wrote:

We actually want these tests to be partially-reduced now so you could remove the `not` part of the name (same for the other file).

https://github.com/llvm/llvm-project/pull/124268