Teach jump threading some more simple tricks:
1) have it fold "br undef", which does occur with
surprising frequency as jump threading iterates.
2) teach j-t to delete dead blocks. This removes the successor
edges, reducing the in-edges of other blocks, allowing
recursive simplification.
3) Fold things like:
br COND, BBX, BBY
BBX:
br COND, BBZ, BBW
which also happens because jump threading iterates.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60470 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Transforms/JumpThreading/basic.ll b/test/Transforms/JumpThreading/basic.ll
index 5d99a7c..bf746e7 100644
--- a/test/Transforms/JumpThreading/basic.ll
+++ b/test/Transforms/JumpThreading/basic.ll
@@ -29,3 +29,25 @@
F2:
ret i32 %B
}
+
+
+;; cond is known false on Entry -> F1 edge!
+define i32 @test2(i1 %cond) {
+Entry:
+ br i1 %cond, label %T1, label %F1
+
+T1:
+ %v1 = call i32 @f1()
+ br label %Merge
+
+F1:
+ br i1 %cond, label %Merge, label %F2
+
+Merge:
+ %B = phi i32 [47, %T1], [192, %F1]
+ ret i32 %B
+
+F2:
+ call void @f3()
+ ret i32 12
+}