new testcase that condprop should handle. The PHI node becomes useless

after threading the branch, because both operands are the same value.

llvm-svn: 22668

test/Regression/Transforms/CondProp/phisimplify2.ll

@@ -0,0 +1,36 @@
+; RUN: llvm-as < %s | opt -condprop | llvm-dis | not grep phi
+
+declare bool %foo()
+
+int %test(uint %C) {
+ 	%Val = call bool %foo()
+        switch uint %C, label %T1 [
+                 uint 4, label %T2
+                 uint 17, label %T3
+        ]
+T1:
+	call void %a()
+	br label %Cont
+T2:
+	call void %b()
+	br label %Cont
+T3:
+	call void %c()
+	br label %Cont
+
+Cont:
+	;; PHI becomes dead after threading T2
+	%C2 = phi bool [%Val, %T1], [true, %T2], [%Val, %T3]
+	br bool %C2, label %L2, label %F2
+L2:
+	call void %d()
+	ret int 17
+F2:
+	call void %e()
+	ret int 1
+}
+declare void %a()
+declare void %b()
+declare void %c()
+declare void %d()
+declare void %e()