[llvm] [LV] Fix issue in VPFirstOrderRecurrencePHIRecipe::usesFirstLaneOnly (PR #179977)

[Florian Hahn via llvm-commits]

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@@ -380,3 +380,58 @@ exit:
   ret void
 }
 
+define void @pr179671(ptr align 8 dereferenceable(120) %p, ptr %a, i32 %b, i1 %flag) {
+; CHECK-LABEL: define void @pr179671(
+; CHECK:       vector.body:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %vector.ph ], [ [[INDEX_NEXT:%.*]], %vector.body ]
+; CHECK-NEXT:    [[VECTOR_RECUR:%.*]] = phi ptr [ %a, %vector.ph ], [ [[NEXT_GEP3:%.*]], %vector.body ]
+; CHECK-NEXT:    [[DOTCAST1:%.*]] = trunc i64 [[INDEX]] to i32
+; CHECK-NEXT:    [[TMP10:%.*]] = mul i32 [[DOTCAST1]], 3
+; CHECK-NEXT:    [[OFFSET_IDX:%.*]] = add i32 %b, [[TMP10]]
+; CHECK-NEXT:    [[TMP11:%.*]] = add i32 [[OFFSET_IDX]], 3
+; CHECK-NEXT:    [[OFFSET_IDX2:%.*]] = mul i64 [[INDEX]], 128
+; CHECK-NEXT:    [[TMP15:%.*]] = add i64 [[OFFSET_IDX2]], 0
+; CHECK-NEXT:    [[TMP12:%.*]] = add i64 [[OFFSET_IDX2]], 128
+; CHECK-NEXT:    [[NEXT_GEP:%.*]] = getelementptr i8, ptr null, i64 [[TMP15]]
+; CHECK-NEXT:    [[NEXT_GEP3]] = getelementptr i8, ptr null, i64 [[TMP12]]
+; CHECK-NEXT:    store ptr [[VECTOR_RECUR]], ptr [[NEXT_GEP]], align 8
+; CHECK-NEXT:    store ptr [[NEXT_GEP]], ptr [[NEXT_GEP3]], align 8
+; CHECK-NEXT:    store ptr [[NEXT_GEP3]], ptr [[INV_PTR:%.*]], align 8
+; CHECK-NEXT:    [[TMP13:%.*]] = add i32 [[TMP11]], 3
+; CHECK-NEXT:    store i32 [[TMP13]], ptr [[INV_PTR2:%.*]], align 8
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP14:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC:%.*]]
+; CHECK-NEXT:    br i1 [[TMP14]], label %[[LOOP_1:.*]], label %vector.body
+entry:
+  br i1 %flag, label %loop.1.ph, label %exit
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fhahn wrote:

Is this needed? It seems like this would be independent of the loop

https://github.com/llvm/llvm-project/pull/179977