JumpThreading: when default destination is the destination of some cases in a

switch, make sure we include the value for the cases when calculating edge
value from switch to the default destination.

rdar://12241132


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163270 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 42 insertions, 3 deletions

diff --git a/lib/Analysis/LazyValueInfo.cpp b/lib/Analysis/LazyValueInfo.cpp
index c2306b4e9c..ec618fad22 100644
--- a/lib/Analysis/LazyValueInfo.cpp
+++ b/lib/Analysis/LazyValueInfo.cpp
@@ -847,9 +847,12 @@ static bool getEdgeValueLocal(Value *Val, BasicBlock *BBFrom,
     for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
          i != e; ++i) {
       ConstantRange EdgeVal(i.getCaseValue()->getValue());
-      if (DefaultCase)
-        EdgesVals = EdgesVals.difference(EdgeVal);
-      else if (i.getCaseSuccessor() == BBTo)
+      if (DefaultCase) {
+        // It is possible that the default destination is the destination of
+        // some cases. There is no need to perform difference for those cases.
+        if (i.getCaseSuccessor() != BBTo)
+          EdgesVals = EdgesVals.difference(EdgeVal);
+      } else if (i.getCaseSuccessor() == BBTo)
         EdgesVals = EdgesVals.unionWith(EdgeVal);
     }
     Result = LVILatticeVal::getRange(EdgesVals);
diff --git a/test/Transforms/JumpThreading/select.ll b/test/Transforms/JumpThreading/select.ll
index 8a81857736..9676efec9d 100644
--- a/test/Transforms/JumpThreading/select.ll
+++ b/test/Transforms/JumpThreading/select.ll
@@ -121,3 +121,39 @@ L4:
   call void @quux()
   br label %L0
 }
+
+; Make sure the edge value of %0 from entry to L2 includes 0 and L3 is
+; reachable.
+; CHECK: test_switch_default
+; CHECK: entry:
+; CHECK: load
+; CHECK: switch
+; CHECK: [[THREADED:[A-Za-z.0-9]+]]:
+; CHECK: store
+; CHECK: br
+; CHECK: L2:
+; CHECK: icmp
+define void @test_switch_default(i32* nocapture %status) nounwind {
+entry:
+  %0 = load i32* %status, align 4
+  switch i32 %0, label %L2 [
+    i32 5061, label %L1
+    i32 0, label %L2
+  ]
+
+L1:
+  store i32 10025, i32* %status, align 4
+  br label %L2
+
+L2:
+  %1 = load i32* %status, align 4
+  %cmp57.i = icmp eq i32 %1, 0
+  br i1 %cmp57.i, label %L3, label %L4
+
+L3:
+  store i32 10000, i32* %status, align 4
+  br label %L4
+
+L4:
+  ret void
+}