Constant::IsThreadDependent(): Use dyn_cast<Constant> instead of cast

It turns out that the operands of a Constant are not always themselves
Constant. For example, one of the operands of BlockAddress is
BasicBlock, which is not a Constant.

This should fix the dragonegg-x86_64-linux-gcc-4.6-test build which
broke in r168037.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168147 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 23 insertions, 1 deletions

diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp
index eae96ef86c..935f6b2bc1 100644
--- a/lib/VMCore/Constants.cpp
+++ b/lib/VMCore/Constants.cpp
@@ -261,7 +261,9 @@ bool Constant::isThreadDependent() const {
     }
 
     for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I) {
-      const Constant *D = cast<Constant>(C->getOperand(I));
+      const Constant *D = dyn_cast<Constant>(C->getOperand(I));
+      if (!D)
+        continue;
       if (Visited.insert(D))
         WorkList.push_back(D);
     }
diff --git a/test/Transforms/GlobalOpt/blockaddress.ll b/test/Transforms/GlobalOpt/blockaddress.ll
new file mode 100644
index 0000000000..13da76299d
--- /dev/null
+++ b/test/Transforms/GlobalOpt/blockaddress.ll
@@ -0,0 +1,20 @@
+; RUN: opt < %s -globalopt -S | FileCheck %s
+
+@x = internal global i8* zeroinitializer
+
+define void @f() {
+; CHECK: @f
+
+; Check that we don't hit an assert in Constant::IsThreadDependent()
+; when storing this blockaddress into a global.
+
+  store i8* blockaddress(@g, %here), i8** @x, align 8
+  ret void
+}
+
+define void @g() {
+; CHECK: @g
+
+here:
+  ret void
+}