Add check that phi nodes get constant propogated away

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2541 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/ConstProp/phi.ll

@@ -0,0 +1,18 @@
+; This is a basic sanity check for constant propogation.  The add instruction 
+; should be eliminated.
+
+; RUN: if as < %s | opt -constprop -die | dis | grep phi
+; RUN: then exit 1
+; RUN: else exit 0
+; RUN: fi
+
+int "test"(bool %B)
+begin
+BB0:
+	br bool %B, label %BB1, label %BB3
+BB1:
+	br label %BB3
+BB3:
+	%Ret = phi int [1, %BB0], [1, %BB1]
+	ret int %Ret
+end