[llvm] [SCEV] Try to re-use existing LCSSA phis when expanding SCEVAddRecExpr. (PR #147214)

[Florian Hahn via llvm-commits]

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@@ -18,11 +18,9 @@ define void @reuse_lcssa_phi_for_add_rec1(ptr %head) {
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw i64 [[IV]], 1
 ; CHECK-NEXT:    br i1 [[EC_1]], label %[[PH:.*]], label %[[LOOP_1]]
 ; CHECK:       [[PH]]:
-; CHECK-NEXT:    [[IV_2_LCSSA:%.*]] = phi i32 [ [[IV_2]], %[[LOOP_1]] ]
 ; CHECK-NEXT:    [[IV_LCSSA:%.*]] = phi i64 [ [[IV]], %[[LOOP_1]] ]
-; CHECK-NEXT:    [[IV_2_NEXT_LCSSA:%.*]] = phi i32 [ [[IV_2_NEXT]], %[[LOOP_1]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = phi i32 [ [[IV_2_NEXT]], %[[LOOP_1]] ]
 ; CHECK-NEXT:    [[SRC_2:%.*]] = tail call noalias noundef dereferenceable_or_null(8) ptr @calloc(i64 1, i64 8)
-; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[IV_2_LCSSA]], 1
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fhahn wrote:

The original version has `tmp0 = %iv.2 + 1`, in the new version `tmp0 = iv.2.next` which should also be `%iv.2 + 1`

https://github.com/llvm/llvm-project/pull/147214