[llvm] [LV] Relax high loop trip count threshold for deciding to interleave a loop (PR #67725)

[David Sherwood via llvm-commits]

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@@ -9,11 +9,19 @@
 define zeroext i8 @sum() {
 ; CHECK-LABEL: @sum(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[WIDE_LOAD2:%.*]] = load <64 x i8>, ptr getelementptr inbounds ([128 x i8], ptr @bytes, i64 0, i64 64), align 1
-; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <64 x i8>, ptr @bytes, align 1
-; CHECK-NEXT:    [[BIN_RDX:%.*]] = add <64 x i8> [[WIDE_LOAD2]], [[WIDE_LOAD]]
-; CHECK-NEXT:    [[TMP0:%.*]] = call i8 @llvm.vector.reduce.add.v64i8(<64 x i8> [[BIN_RDX]])
-; CHECK-NEXT:    ret i8 [[TMP0]]
+; CHECK-NEXT:    br label [[VECTOR_BODY:%.*]]
+; CHECK:       vector.body:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI:%.*]] = phi <64 x i8> [ zeroinitializer, [[ENTRY]] ], [ [[TMP1:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds [128 x i8], ptr @bytes, i64 0, i64 [[INDEX]]
+; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <64 x i8>, ptr [[TMP0]], align 1
+; CHECK-NEXT:    [[TMP1]] = add <64 x i8> [[WIDE_LOAD]], [[VEC_PHI]]
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 64
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i64 [[INDEX_NEXT]], 128
+; CHECK-NEXT:    br i1 [[TMP2]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
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david-arm wrote:

This looks worse than before. Do you know why we haven't removed the loop here?

https://github.com/llvm/llvm-project/pull/67725