ADT: Separate some list manipulation API into ilist_base, NFC

Separate algorithms in iplist<T> that don't depend on T into ilist_base,
and unit test them.

While I was adding unit tests for these algorithms anyway, I also added
unit tests for ilist_node_base and ilist_sentinel<T>.

To make the algorithms and unit tests easier to write, I also did the
following minor changes as a drive-by:
- encapsulate Prev/Next in ilist_node_base to so that algorithms are
  easier to read, and
- update ilist_node_access API to take nodes by reference.

There should be no real functionality change here.

llvm-svn: 279484

1 files changed, 37 insertions, 0 deletions

diff --git a/llvm/unittests/ADT/IListSentinelTest.cpp b/llvm/unittests/ADT/IListSentinelTest.cpp
new file mode 100644
index 00000000000..533421e8504
--- /dev/null
+++ b/llvm/unittests/ADT/IListSentinelTest.cpp
@@ -0,0 +1,37 @@
+//===- unittests/ADT/IListSentinelTest.cpp - ilist_sentinel unit tests ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/ilist.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+class Node : public ilist_node<Node> {};
+
+TEST(IListSentinelTest, DefaultConstructor) {
+  ilist_sentinel<Node> S;
+  EXPECT_EQ(&S, ilist_node_access::getPrev(S));
+  EXPECT_EQ(&S, ilist_node_access::getNext(S));
+#ifdef LLVM_ENABLE_ABI_BREAKING_CHECKS
+  EXPECT_TRUE(S.isKnownSentinel());
+#else
+  EXPECT_FALSE(S.isKnownSentinel());
+#endif
+}
+
+TEST(IListSentinelTest, NormalNodeIsNotKnownSentinel) {
+  Node N;
+  EXPECT_EQ(nullptr, ilist_node_access::getPrev(N));
+  EXPECT_EQ(nullptr, ilist_node_access::getNext(N));
+  EXPECT_FALSE(N.isKnownSentinel());
+}
+
+} // end namespace