Teach RecursivelyDeleteDeadPHINodes to handle multiple self-references. Patch

by Andrew Clinton!

llvm-svn: 126077

1 files changed, 49 insertions, 0 deletions

diff --git a/llvm/unittests/Transforms/Utils/Local.cpp b/llvm/unittests/Transforms/Utils/Local.cpp
new file mode 100644
index 0000000..e969e95
--- /dev/null
+++ b/llvm/unittests/Transforms/Utils/Local.cpp
@@ -0,0 +1,49 @@
+//===- Local.cpp - Unit tests for Local -----------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Instructions.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Support/IRBuilder.h"
+#include "llvm/Transforms/Utils/Local.h"
+
+using namespace llvm;
+
+TEST(Local, RecursivelyDeleteDeadPHINodes) {
+  LLVMContext &C(getGlobalContext());
+
+  IRBuilder<> builder(C);
+
+  // Make blocks
+  BasicBlock *bb0 = BasicBlock::Create(C);
+  BasicBlock *bb1 = BasicBlock::Create(C);
+
+  builder.SetInsertPoint(bb0);
+  PHINode    *phi = builder.CreatePHI(Type::getInt32Ty(C));
+  BranchInst *br0 = builder.CreateCondBr(builder.getTrue(), bb0, bb1);
+
+  builder.SetInsertPoint(bb1);
+  BranchInst *br1 = builder.CreateBr(bb0);
+
+  phi->addIncoming(phi, bb0);
+  phi->addIncoming(phi, bb1);
+
+  // The PHI will be removed
+  EXPECT_TRUE(RecursivelyDeleteDeadPHINode(phi));
+
+  // Make sure the blocks only contain the branches
+  EXPECT_EQ(&bb0->front(), br0);
+  EXPECT_EQ(&bb1->front(), br1);
+
+  bb0->dropAllReferences();
+  bb1->dropAllReferences();
+  delete bb0;
+  delete bb1;
+}