Tolerate degenerate phi nodes that can occur in the middle of optimization
passes. Fixes PR9112. Patch by Jakub Staszak!
llvm-svn: 125319
diff --git a/llvm/test/Transforms/JumpThreading/degenerate-phi.ll b/llvm/test/Transforms/JumpThreading/degenerate-phi.ll
new file mode 100644
index 0000000..35d9fde
--- /dev/null
+++ b/llvm/test/Transforms/JumpThreading/degenerate-phi.ll
@@ -0,0 +1,24 @@
+; RUN: opt -jump-threading -disable-output %s
+; PR9112
+
+; This is actually a test for value tracking. Jump threading produces
+; "%phi = phi i16" when it removes all edges leading to %unreachable.
+; The .ll parser won't let us write that directly since it's invalid code.
+
+define void @func() nounwind {
+entry:
+ br label %bb
+
+bb:
+ br label %bb
+
+unreachable:
+ %phi = phi i16 [ %add, %unreachable ], [ 0, %next ]
+ %add = add i16 0, %phi
+ %cmp = icmp slt i16 %phi, 0
+ br i1 %cmp, label %unreachable, label %next
+
+next:
+ br label %unreachable
+}
+