1 files changed, 35 insertions, 0 deletions
diff --git a/test/Analysis/ScalarEvolution/2008-11-18-Stride1.ll b/test/Analysis/ScalarEvolution/2008-11-18-Stride1.ll
new file mode 100644
index 0000000..db527fe
--- /dev/null
+++ b/test/Analysis/ScalarEvolution/2008-11-18-Stride1.ll
@@ -0,0 +1,35 @@
+; RUN: opt < %s -analyze -scalar-evolution \
+; RUN:  | grep {Loop %bb: Unpredictable backedge-taken count\\.}
+
+; ScalarEvolution can't compute a trip count because it doesn't know if
+; dividing by the stride will have a remainder. This could theoretically
+; be teaching it how to use a more elaborate trip count computation.
+
+define i32 @f(i32 %x) nounwind readnone {
+entry:
+	%0 = icmp ugt i32 %x, 4		; <i1> [#uses=1]
+	br i1 %0, label %bb.nph, label %bb2
+
+bb.nph:		; preds = %entry
+	br label %bb
+
+bb:		; preds = %bb.nph, %bb1
+	%indvar = phi i32 [ 0, %bb.nph ], [ %indvar.next, %bb1 ]		; <i32> [#uses=2]
+	%tmp = mul i32 %indvar, -3		; <i32> [#uses=1]
+	%x_addr.04 = add i32 %tmp, %x		; <i32> [#uses=1]
+	%1 = add i32 %x_addr.04, -3		; <i32> [#uses=2]
+	br label %bb1
+
+bb1:		; preds = %bb
+	%2 = icmp ugt i32 %1, 4		; <i1> [#uses=1]
+	%indvar.next = add i32 %indvar, 1		; <i32> [#uses=1]
+	br i1 %2, label %bb, label %bb1.bb2_crit_edge
+
+bb1.bb2_crit_edge:		; preds = %bb1
+	%.lcssa = phi i32 [ %1, %bb1 ]		; <i32> [#uses=1]
+	br label %bb2
+
+bb2:		; preds = %bb1.bb2_crit_edge, %entry
+	%x_addr.0.lcssa = phi i32 [ %.lcssa, %bb1.bb2_crit_edge ], [ %x, %entry ]		; <i32> [#uses=1]
+	ret i32 %x_addr.0.lcssa
+}