make jump threading on a phi with undef inputs happen.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83754 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/JumpThreading/basic.ll

@@ -1,6 +1,4 @@
 ; RUN: opt < %s -jump-threading -S | FileCheck %s
-; There should be no uncond branches left.
-; RUN: opt < %s -jump-threading -S | not grep {br label}
 
 declare i32 @f1()
 declare i32 @f2()
@@ -75,3 +73,35 @@ T1:
 F1:
 	ret i32 17
 }
+
+define i32 @test4(i1 %cond, i1 %cond2) {
+; CHECK: @test4
+
+	br i1 %cond, label %T1, label %F1
+
+T1:
+; CHECK:   %v1 = call i32 @f1()
+; CHECK-NEXT:   br label %T
+
+	%v1 = call i32 @f1()
+	br label %Merge
+
+F1:
+	%v2 = call i32 @f2()
+; CHECK:   %v2 = call i32 @f2()
+; CHECK-NEXT:   br i1 %cond2, 
+	br label %Merge
+
+Merge:
+	%A = phi i1 [undef, %T1], [%cond2, %F1]
+	%B = phi i32 [%v1, %T1], [%v2, %F1]
+	br i1 %A, label %T2, label %F2
+
+T2:
+	call void @f3()
+	ret i32 %B
+
+F2:
+	ret i32 %B
+}
+