--- /dev/null
+; RUN: llvm-as < %s | opt -simplifycfg | llvm-dis | not grep 'call void %DEAD'
+
+; Test that we can thread a simple known condition through switch statements.
+
+declare void %foo1()
+declare void %foo2()
+declare void %DEAD()
+
+void %test1(uint %V) {
+ switch uint %V, label %A [
+ uint 4, label %T
+ uint 17, label %Done
+ uint 1234, label %A
+ ]
+
+T: ;; V == 4 if we get here.
+ call void %foo1()
+ ;; This switch is always statically determined.
+ switch uint %V, label %A2 [
+ uint 4, label %B
+ uint 17, label %C
+ uint 42, label %C
+ ]
+A2:
+ call void %DEAD()
+ call void %DEAD()
+ %cond2 = seteq uint %V, 4 ;; always false
+ br bool %cond2, label %Done, label %C
+
+A:
+ call void %foo1()
+ %cond = setne uint %V, 4 ;; always true
+ br bool %cond, label %Done, label %C
+
+
+Done:
+ ret void
+
+B:
+ call void %foo2()
+ %cond3 = seteq uint %V, 4 ;; always true
+ br bool %cond3, label %Done, label %C
+C:
+ call void %DEAD()
+ ret void
+}
+
+void %test2(uint %V) {
+ switch uint %V, label %A [
+ uint 4, label %T
+ uint 17, label %D
+ uint 1234, label %E
+ ]
+
+A: ;; V != 4, 17, 1234 here.
+ call void %foo1()
+ ;; This switch is always statically determined.
+ switch uint %V, label %E [
+ uint 4, label %C
+ uint 17, label %C
+ uint 42, label %D
+ ]
+C:
+ call void %DEAD() ;; unreacahble.
+ ret void
+T:
+ call void %foo1()
+ call void %foo1()
+ ret void
+
+D:
+ call void %foo1()
+ ret void
+
+E:
+ ret void
+}
+