New testcase. Switch instructions that go to switch instructions should be

merged.

llvm-svn: 11796

llvm/test/Regression/Transforms/SimplifyCFG/switch_switch_fold.ll

@@ -0,0 +1,46 @@
+; RUN: llvm-as < %s | opt -simplifycfg | llvm-dis | grep switch | wc -l | grep 1
+
+; Test that a switch going to a switch on the same value can be merged.   All 
+; three switches in this example can be merged into one big one.
+
+declare void %foo1()
+declare void %foo2()
+declare void %foo3()
+declare void %foo4()
+
+void %test1(uint %V) {
+        switch uint %V, label %F [
+                 uint 4, label %T
+                 uint 17, label %T
+                 uint 5, label %T
+                 uint 1234, label %F
+        ]
+
+T:
+        switch uint %V, label %F [
+                 uint 4, label %A
+                 uint 17, label %B
+		 uint 42, label %C
+        ]
+A:
+        call void %foo1()
+        ret void
+
+B:
+        call void %foo2()
+        ret void
+C:
+	call void %foo3()
+	ret void
+
+F:
+        switch uint %V, label %F [
+                 uint 4, label %B
+                 uint 18, label %B
+		 uint 42, label %D
+        ]
+D:
+        call void %foo4()
+        ret void
+}
+