IR: Fix BasicBlock::phis for empty blocks
llvm-svn: 321567
diff --git a/llvm/lib/IR/BasicBlock.cpp b/llvm/lib/IR/BasicBlock.cpp
index 2251392..938c401 100644
--- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -264,7 +264,8 @@
}
iterator_range<BasicBlock::phi_iterator> BasicBlock::phis() {
- return make_range<phi_iterator>(dyn_cast<PHINode>(&front()), nullptr);
+ PHINode *P = empty() ? nullptr : dyn_cast<PHINode>(&*begin());
+ return make_range<phi_iterator>(P, nullptr);
}
/// This method is used to notify a BasicBlock that the
diff --git a/llvm/unittests/IR/BasicBlockTest.cpp b/llvm/unittests/IR/BasicBlockTest.cpp
index f1777e3..08a41ff 100644
--- a/llvm/unittests/IR/BasicBlockTest.cpp
+++ b/llvm/unittests/IR/BasicBlockTest.cpp
@@ -33,6 +33,12 @@
std::unique_ptr<BasicBlock> BB2(BasicBlock::Create(Context));
BranchInst::Create(BB.get(), BB2.get());
+ // Make sure this doesn't crash if there are no phis.
+ for (auto &PN : BB->phis()) {
+ (void)PN;
+ EXPECT_TRUE(false) << "empty block should have no phis";
+ }
+
// Make it a cycle.
auto *BI = BranchInst::Create(BB.get(), BB.get());