[llvm] [LV] Use SCEV to check if minimum iteration check is known. (PR #111310)

[via llvm-commits]

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@@ -423,8 +423,7 @@ define void @zext_of_i1_stride(i1 %g, ptr %dst) mustprogress {
 ; CHECK-NEXT:    [[G_64:%.*]] = zext i1 [[G]] to i64
 ; CHECK-NEXT:    [[TMP0:%.*]] = udiv i64 15, [[G_64]]
 ; CHECK-NEXT:    [[TMP1:%.*]] = add nuw nsw i64 [[TMP0]], 1
-; CHECK-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[TMP1]], 4
-; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_SCEVCHECK:%.*]]
+; CHECK-NEXT:    br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_SCEVCHECK:%.*]]
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ayalz wrote:

Count of 16 (assuming G = 1) is known to be greater than step of 4.

https://github.com/llvm/llvm-project/pull/111310