Bail on unswitching a switch statement for a case with a critical edge. We name

which edge to split by pred/succ pair, which means that we can end up splitting
the wrong edge (by case value) in the switch statement entirely. Fixes PR10031!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132535 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 28 insertions, 0 deletions

diff --git a/test/Transforms/LoopUnswitch/2011-06-02-CritSwitch.ll b/test/Transforms/LoopUnswitch/2011-06-02-CritSwitch.ll
new file mode 100644
index 0000000000..61c54ddb15
--- /dev/null
+++ b/test/Transforms/LoopUnswitch/2011-06-02-CritSwitch.ll
@@ -0,0 +1,28 @@
+; RUN: opt -loop-unswitch -disable-output
+; PR10031
+
+define i32 @test(i32 %command) {
+entry:
+  br label %tailrecurse
+
+tailrecurse:                                      ; preds = %if.then14, %tailrecurse, %entry
+  br i1 undef, label %if.then, label %tailrecurse
+
+if.then:                                          ; preds = %tailrecurse
+  switch i32 %command, label %sw.bb [
+    i32 2, label %land.lhs.true
+    i32 0, label %land.lhs.true
+  ]
+
+land.lhs.true:                                    ; preds = %if.then, %if.then
+  br i1 undef, label %sw.bb, label %if.then14
+
+if.then14:                                        ; preds = %land.lhs.true
+  switch i32 %command, label %tailrecurse [
+    i32 0, label %sw.bb
+    i32 1, label %sw.bb
+  ]
+
+sw.bb:                                            ; preds = %if.then14
+  unreachable
+}