GlobalDCE: Fix an oversight in my last commit that could lead to crashes.

There is a Constant with non-constant operands: blockaddress.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179460 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 2 deletions

diff --git a/lib/Transforms/IPO/GlobalDCE.cpp b/lib/Transforms/IPO/GlobalDCE.cpp
index 76d1287fb7..201f320c43 100644
--- a/lib/Transforms/IPO/GlobalDCE.cpp
+++ b/lib/Transforms/IPO/GlobalDCE.cpp
@@ -197,8 +197,8 @@ void GlobalDCE::MarkUsedGlobalsAsNeeded(Constant *C) {
   // use to the list of needed globals.
   for (User::op_iterator I = C->op_begin(), E = C->op_end(); I != E; ++I) {
     // If we've already processed this constant there's no need to do it again.
-    Constant *Op = cast<Constant>(*I);
-    if (SeenConstants.insert(Op))
+    Constant *Op = dyn_cast<Constant>(*I);
+    if (Op && SeenConstants.insert(Op))
       MarkUsedGlobalsAsNeeded(Op);
   }
 }
diff --git a/test/Transforms/GlobalDCE/indirectbr.ll b/test/Transforms/GlobalDCE/indirectbr.ll
new file mode 100644
index 0000000000..90f1ae44b1
--- /dev/null
+++ b/test/Transforms/GlobalDCE/indirectbr.ll
@@ -0,0 +1,18 @@
+; RUN: opt -S -globaldce < %s | FileCheck %s
+
+@L = internal unnamed_addr constant [3 x i8*] [i8* blockaddress(@test1, %L1), i8* blockaddress(@test1, %L2), i8* null], align 16
+
+; CHECK: @L = internal unnamed_addr constant
+
+define void @test1(i32 %idx) {
+entry:
+  br label %L1
+
+L1:
+  %arrayidx = getelementptr inbounds [3 x i8*]* @L, i32 0, i32 %idx
+  %l = load i8** %arrayidx
+  indirectbr i8* %l, [label %L1, label %L2]
+
+L2:
+  ret void
+}