--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/Feature/cfgstructures.ll	Thu Dec 12 13:56:28 2013 +0900
@@ -0,0 +1,53 @@
+; RUN: llvm-as < %s | llvm-dis > %t1.ll
+; RUN: llvm-as %t1.ll -o - | llvm-dis > %t2.ll
+; RUN: diff %t1.ll %t2.ll
+
+;; This is an irreducible flow graph
+define void @irreducible(i1 %cond) {
+        br i1 %cond, label %X, label %Y
+
+X:              ; preds = %Y, %0
+        br label %Y
+
+Y:              ; preds = %X, %0
+        br label %X
+}
+
+;; This is a pair of loops that share the same header
+define void @sharedheader(i1 %cond) {
+        br label %A
+
+A:              ; preds = %Y, %X, %0
+        br i1 %cond, label %X, label %Y
+
+X:              ; preds = %A
+        br label %A
+
+Y:              ; preds = %A
+        br label %A
+}
+
+
+;; This is a simple nested loop
+define void @nested(i1 %cond1, i1 %cond2, i1 %cond3) {
+        br label %Loop1
+
+Loop1:          ; preds = %L2Exit, %0
+        br label %Loop2
+
+Loop2:          ; preds = %L3Exit, %Loop1
+        br label %Loop3
+
+Loop3:          ; preds = %Loop3, %Loop2
+        br i1 %cond3, label %Loop3, label %L3Exit
+
+L3Exit:         ; preds = %Loop3
+        br i1 %cond2, label %Loop2, label %L2Exit
+
+L2Exit:         ; preds = %L3Exit
+        br i1 %cond1, label %Loop1, label %L1Exit
+
+L1Exit:         ; preds = %L2Exit
+        ret void
+}
+